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1
Ohta, Hiroyuki, and Takumi Nakagawa. "Using Ceramic Balls to Reduce Noise in a Linear Guideway Type Recirculating Linear Ball Bearing." Journal of Tribology 125, no. 3 (June 19, 2003): 480–86. http://dx.doi.org/10.1115/1.1537264.
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A new method of reducing the noise of the linear guideway type recirculating linear ball bearing (linear bearing) was studied. In the experiments, the overall sound pressure levels of linear bearings with steel balls or ceramic Si3N4 balls were measured, and sound frequency analyses were carried out. Moreover, based on the assumption that the main cause of the noise may be the collision between the ball and the carriage, the overall sound pressure levels of the linear bearings were analyzed combining the Hertzian theory and the results of previous studies on collision sound. From the results of experiments and analyses, the conclusions were obtained as follows: (1) The overall sound pressure level of the linear bearing with steel balls can be reduced by about 4.5 dB by using Si3N4 balls having the same diameter; (2) The overall sound pressure levels of linear bearings with steel balls or ceramic Si3N4 balls were both increased by about 9.8 dB as the linear velocity increased an octave; and (3) The analytical results, based on the assumption that the main cause of the noise emitted from the linear bearings is the collision between the ball and the carriage, match the experimental results well.
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MacLean, Gail L., Andrew Stuart, and Robert Stenstrom. "Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones." American Journal of Audiology 1, no. 4 (November 1992): 52–55. http://dx.doi.org/10.1044/1059-0889.0104.52.
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Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.
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Ramesh, Ananthapadmanabhan, and Sundar Sriram. "Variation in vibro-acoustic noise due to the defects in an automotive drum brake." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 4 (August 1, 2021): 2646–53. http://dx.doi.org/10.3397/in-2021-2192.
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Drum brakes are significant contributors to noise and vibration in automobiles causing discomfort to the passengers. The vibration and hence the resulting noise increase due to various inherent defects in the drum brake, such as asymmetry. This work aims to quantify the variation in the vibro-acoustic noise due to several common defects in the drum brake using an integrated non-linear vibration analytical model and a numerical acoustic model. The sources of vibro-acoustic noise sources such as contact and reaction forces are predicted using a four-degree-of-freedom non-linear contact mechanics based analytical model. A finite element based acoustic model of the drum brake is utilized to predict the force to the sound pressure transfer function in the drum brake. Product of the transfer functions and the forces gives the corresponding sound pressure level from which the overall sound pressure levels are estimated. The variation in the overall sound pressure levels due to different drum brake defects is evaluated by introducing defects to the analytical model. The results show that the overall sound pressure level is a strong function of the defects. It is envisioned that the current work will help in the development of effective health monitoring systems.
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Lieberman, Paul. "High-Intensity Acoustic Test Facility Using Hydraulics." Journal of the IEST 42, no. 1 (January 14, 1999): 46–50. http://dx.doi.org/10.17764/jiet.42.1.b3v5838g823m260v.
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The hour-long duration acoustic fatigue tests at levels above 190 dB overall sound pressure level (OASPL) can be achieved with the required sound pressure level (SPL) spectrum using available test facilities with a hydraulic simulator, which operates at only 3 to 10 psi. Furthermore, the hydraulic control at the low frequencies is available, whereas there is a 50-Hz frequency cutoff for acoustic test facilities. Many structures have destructive low-frequency resonant modes which would be properly excited in the hydraulic facility and not in the acoustic facility.
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Zhu, Chunli, Hassan Hemida, Dominic Flynn, Chris Baker, Xifeng Liang, and Dan Zhou. "Numerical simulation of the slipstream and aeroacoustic field around a high-speed train." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 231, no. 6 (April 4, 2016): 740–56. http://dx.doi.org/10.1177/0954409716641150.
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The flow field and sound propagation around a three-coach 1/8th scale high-speed passenger train were obtained using a detached-eddy simulation and the Ffowcs-Williams and Hawkings acoustic analogy. The Reynolds number of flow based on the train height and speed was 2,000,000. The numerical results of the flow and aeroacoustic fields were validated using wind tunnel experiments and full-scale data, respectively. Features of overall sound pressure level, sound pressure level and A-weighted sound pressure level of typical measuring points are discussed. The sound propagated by a high-speed train is shown as a broadband noise spectrum including tonal component, where high sound pressure levels are concentrated on the low-frequency range from 10 Hz to 300 Hz. The inter-carriage gap is found to cause distinct tonal noise in contrast to the other parts of the train that cause a broadband noise. The negative log law has been used to study the influence of distance from the centre of track on the sound pressure level, where a good fit is shown at low-frequency ranges. The peak values of A-weighted sound pressure level from both full-scale experiment and simulation results occur at approximately 1 kHz, where simulation results show almost the same range as the experiment. The surface of each component of the train as well as the whole train are chosen as the integral surface for the Ffowcs-Williams and Hawkings computation of the far-field noise characteristics. It was found that the sound source generated by a high-speed train is mainly dipole, and the largest noise was obtained from the leading bogie. The results of this paper provide, for the first time, a better understanding of the aeroacoustic field around a three-coach train model, and the paper has the potential to assist engineers to design high-speed trains with aeroacoustic noise reduction in a better manner.
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Ruhala, Richard, Courtney Burroughs, and Laura Ruhala. "Comparison of roadwheel and roadway noise generated by a mono-pitch tire tread." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 3 (August 1, 2021): 3571–83. http://dx.doi.org/10.3397/in-2021-2455.
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Tire-pavement interaction noise (TPIN, aka tire-road noise or tyre-road noise) is most efficiently measured in acoustically controlled laboratories with large diameter roadwheels (drums) that have surface treatments which replicate some pavement properties, especially when comparing the acoustic performance of different tires. However, it is not clear how closely the roadwheel replicates the road surface, including differences that include road curvature and mechanical impedance of pavements. On the other hand, measuring on a moving vehicle with a microphone array presents it own set of challenges. In this study, a Nearfield Acoustical Holography (NAH) method is used to measure tire/pavement interaction noise on roadways and roadwheels with similar smooth pavement and rough pavement properties. Sound intensity fields, overall sound power levels, and sound pressure levels are reconstructed very close to the tire surface. An experimental passenger car tire with a mono-pitch tread is used in this study. The experimental tire has three circumferential grooves and 64 equally spaced transverse grooves cut into the tread. Differences in sound fields and levels between roadway and roadwheel test conditions for this tire are shown.
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Baker, Kristin K., Lorraine Olson Ramig, Shimon Sapir, Erich S. Luschei, and Marshall E. Smith. "Control of Vocal Loudness in Young and Old Adults." Journal of Speech, Language, and Hearing Research 44, no. 2 (April 2001): 297–305. http://dx.doi.org/10.1044/1092-4388(2001/024).
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This study examined the effect of aging on respiratory and laryngeal mechanisms involved in vocal loudness control. Simultaneous measures of subglottal pressure and electromyographic (EMG) activity from the thyroarytenoid (TA), lateral cricoarytenoid (LCA), and cricothyroid (CT) muscles were investigated in young and old individuals while they attempted to phonate at three loudness levels, "soft," "comfortable," and "loud." Voice sound pressure level (SPL) and fundamental frequency (F 0 ) measures were also obtained. Across loudness conditions, subglottal pressure levels were similar for both age groups. Laryngeal EMG measures tended to be lower and more variable for old compared with young individuals. These differences were most apparent for the TA muscle. Finally, across the three loudness conditions, the old individuals generated SPLs that were lower overall than those produced by the young individuals but modulated loudness levels in a manner similar to that of the young subjects. These findings suggest that the laryngeal mechanism may be more affected than the respiratory system in these old individuals and that these changes may affect vocal loudness levels.
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Brown, M. C., S. G. Kujawa, and M. L. Duca. "Single Olivocochlear Neurons in the Guinea Pig. I. Binaural Facilitation of Responses to High-Level Noise." Journal of Neurophysiology 79, no. 6 (June 1, 1998): 3077–87. http://dx.doi.org/10.1152/jn.1998.79.6.3077.
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Brown, M. C., S. G. Kujawa, and M. L. Duca. Single olivocochlear neurons in the guinea pig. I. Binaural facilitation of responses to high-level noise. J. Neurophysiol. 79: 3077–3087, 1998. Single medial olivocochlear (MOC) neurons were recorded from the cochlea of the anesthetized guinea pig. We used tones and noise presented monaurally and binaurally and measured responses for sounds up to 105 dB sound pressure level (SPL). For monaural sound, MOC neuron firing rates were usually higher for noise bursts than tone bursts, a situation not observed for afferent fibers of the auditory nerve that were sampled in the same preparations. MOC neurons also differed from afferent fibers in having less saturation of response. Some MOC neurons had responses that continued to increase even at high sound levels. Differences between MOC and afferent responses suggest that there is convergence in the pathway to olivocochlear neurons, possibly a combination of inputs that are at the characteristic frequency (CF) with others that are off the CF. Opposite-ear noise almost always facilitated the responses of MOC neurons to sounds in the main ear, the ear that best drives the unit. This binaural facilitation depends on several characteristics that pertain to the main ear: it is higher in neurons having a contralateral main ear (contra units), it is higher at main-ear sound levels that are moderate (∼65 dB SPL), and it is higher in neurons with low discharge rates to main-ear stimuli. Facilitation also depends on parameters of the opposite-ear sound: facilitation increases with noise level in the opposite ear until saturating, is greater for continuous noise than noise bursts, and is usually greater for noise than for tones. Using optimal opposite-ear facilitators and high-level stimuli, the firing rates of olivocochlear neurons range up to 140 spikes/s, whereas for moderate-level monaural stimuli the rates are <80 spikes/s. At high sound levels, firing rates of olivocochlear neurons increase with CF, an increase that may compensate for the known lower effectiveness of olivocochlear synapses on outer hair cells responding to high frequencies. Overall, our results demonstrate a high MOC response for binaural noise and suggest a prominent role for the MOC system in environments containing binaural noise of high level.
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Nowotny, Łukasz, and Jacek Nurzyński. "Proposal of an Assessment Method of the Impact Sound Insulation of Lightweight Floors." Buildings 10, no. 1 (January 16, 2020): 13. http://dx.doi.org/10.3390/buildings10010013.
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Lightweight floors are in line with a sustainable construction concept and have become increasingly popular in residential buildings. The acoustic performance of such floors plays a pivotal role in the overall building quality rating. There is, however, no clear and complete method to predict their impact sound insulation. A new approximation method and new acoustic indicators—equivalent weighted normalized impact sound pressure levels for lightweight floors—are proposed and outlined in this article. The prediction procedure and indicator values were initially validated on the basis of laboratory measurements taken for different lightweight floors with the same well-defined floor covering. These preliminary analyses and comparisons show that the proposed method is promising and should be fully developed on the basis of further research.
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Slater, M., E. Fricke, M. Weiss, A. Rebelein, M. Bögner, M. Preece, and C. Radford. "The impact of aquaculture soundscapes on whiteleg shrimp Litopenaeus vannamei and Atlantic salmon Salmo salar." Aquaculture Environment Interactions 12 (April 16, 2020): 167–77. http://dx.doi.org/10.3354/aei00355.
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Research into the effects of soundscapes on aquaculture species in key production systems is sparse, despite potential impacts of sound on animal welfare and commercial yields. In the following study, 2 high-value global aquaculture species, whiteleg shrimp Litopenaeus vannamei and Atlantic salmon Salmo salar, were exposed to aquaculture production system soundscapes. For shrimp, sound recordings of a commercial recirculating aquaculture system (RAS) were played back at a sound pressure level (SPL) of 128 dB re 1 µPa, and for salmon, recordings from a commercial sea pen production system were played back at an SPL of 127 dB re 1 µPa for an 8 wk period. Effects of exposure on growth, survival, and indications of metabolic stress were measured as parameters of interest for aquaculture production. Mean growth performance and survival rates did not differ significantly between sound and control treatments for either species. Blood and haemolymph parameters from both species indicated no measurable change in metabolic status or stress levels. Slight, but non-significant, increases in total haemocyte count and, in particular, hyaline cell count were recorded in shrimp exposed to sound. Slight, but non-significant reductions in overall weight gain were recorded in sound-exposed salmon. Overall, the results indicate that sound exposure in current production systems does not negatively affect the early grow-out stage of these key species, either due to rapid habituation or higher hearing thresholds of hatchery-produced individuals, and that no measurable stress response occurs in sound-exposed animals. In future studies, response of the studied species to acute sound exposure and the response of earlier, and potentially more sensitive, life-stages will need to be determined to ensure optimal welfare and production performance.
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Entenmann, D. T., W. E. North, I. Fukue, and A. Muyama. "Shop Test of the 501F—A 150 MW Combustion Turbine." Journal of Engineering for Gas Turbines and Power 113, no. 4 (October 1, 1991): 488–94. http://dx.doi.org/10.1115/1.2906266.
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The 501F is a 150 MW-class 60 Hz engine jointly developed by Westinghouse Electric Corporation and Mitsubishi Heavy Industries, Ltd. This paper describes the full-load shop test program for the prototype engine, as carried out in Takasago, Japan. The shop test included a full range of operating conditions, from startup through full load at the 1260°C (2300°F) design turbine inlet temperature. The engine was prepared with more than 1500 instrumentation points to monitor flow path characteristics, metal temperatures, displacements, pressures, cooling circuit characteristics, strains, sound pressure levels, and exhaust emissions. The results of this shop test indicate the new 501F engine design and development effort to be highly successful. The engine exceeds power and overall efficiency expectations, thus verifying the new concepts and design improvements.
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ALKISLAR, MEHMET B., A. KROTHAPALLI, and G. W. BUTLER. "The effect of streamwise vortices on the aeroacoustics of a Mach 0.9 jet." Journal of Fluid Mechanics 578 (April 26, 2007): 139–69. http://dx.doi.org/10.1017/s0022112007005022.
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The role of the streamwise vortices on the aeroacoustics of a Mach 0.9 axisymmetric jet is investigated using two different devices to generate streamwise vortices: microjets and chevrons. The resultant acoustic field is mapped by sideline microphones and a microphone phased array. The flow-field characteristics within the first few diameters of the nozzle exit are obtained using stereoscopic particle image velocimetry (PIV). The flow-field measurements reveal that the counter-rotating streamwise vortex pairs generated by microjets are located primarily at the high-speed side of the initial shear layer. In contrast, the chevrons generate vortices of greater strength that reside mostly on the low-speed side. Although the magnitude of the chevron's axial vorticity is initially higher, it decays more rapidly with downstream distance. As a result, their influence is confined to a smaller region of the jet. The axial vorticity generated by both devices produces an increase in local entrainment and mixing, increasing the near-field turbulence levels. It is argued that the increase in high-frequency sound pressure levels (SPL) commonly observed in the far-field noise spectrum is due to the increase in the turbulence levels close to the jet exit on the high-speed side of the shear layer. The greater persistence and lower strength of the streamwise vortices generated by microjets appear to shift the cross-over frequencies to higher values and minimize the high-frequency lift in the far-field spectrum. The measured overall sound pressure level (OASPL) shows that microjet injection provides relatively uniform noise suppression for a wider range of sound radiation angles when compared to that of a chevron nozzle.
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Huang, Z. Y., W. K. Jiang, C. H. Liu, H. S. Jin, and Y. Zhou. "Improvement on acoustic performance of the accumulator of double-cylinder rotary compressors." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 11 (November 1, 2007): 1391–96. http://dx.doi.org/10.1243/09544062jmes608.
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Since the accumulator is one of main contributors to the overall noise level of the rotary compressor, research on the acoustic performance of accumulators is essential. Numerical analysis based on the computational fluid dynamic method shows that large pressure fluctuations are caused mainly by periodic rotating piston. The idea that the flow phase differences of two pipes could be utilized for suppressing fluctuations is proposed. The double standpipes of an accumulator are changed to the single pipe with two branches and each branch is connected to the inlet of the compressor. Flow structures and wall pressure fluctuations for the two configurations are computed. Computational results show that wall pressure pulsations of the new accumulator are obviously lower than that of the original. The acoustic experiments were carried out under the real working conditions. Compared with the original, the new accumulator shows that the overall noise level is reduced about 1.2 dB(A) and the sound spectrum levels are also lower in a wide frequency domain, which validate the numerical and theoretical analysis.
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Xu, Wei, and Feng Xu. "Numerical Study on Wind-Induced Noise of High-Rise Building Curtain Wall with Outside Shading Devices." Shock and Vibration 2018 (July 8, 2018): 1–12. http://dx.doi.org/10.1155/2018/5840761.
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Perforation metal plates with dense holes are often used as external curtain walls of high-rise buildings. When air flow passes through these holes at a high speed, complex vortex is generated and causes a significant issue of wind-induced noise. In this study, both Reynolds-averaged Navier–Stokes (RANS) simulations and large-eddy simulations (LES) were conducted to study flow around high-rise buildings with an external sunshade curtain wall. First, wind speed distributions at the height of a typical level under 16 wind directions were acquired. Then, the maximum wind speed ratio and its corresponding azimuth were identified. Second, the sound pressure levels in the vicinity of the shading devices with two types of perforation plate schemes were calculated to evaluate the acoustic characteristics by using the FW-H equation to simulate sound generation and propagation. The results indicate that the maximum wind speed around the buildings exists at the building corners, and the maximum wind speed ratio is 2.8 observed at 0-degree wind direction. Under two different wind conditions, the aeroacoustic performance of perforation plate is enhanced with reducing end plate size and increasing aperture size. The overall sound pressure level (OSPL) and A-weighted sound pressure level (ASPL) around the shading devices are 80 dB and 68 dB(A), respectively, for the improved perforation plate scheme under the 1-year return period maximum speed, which are changed to 58dB and 45dB(A) under the annual average speed. Therefore, it is believed that perforation plates with small end plate size and large aperture size are desirable for the noise prevention design of shading devices.
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Hornberg, Jonas, Timo Haselhoff, Bryce T. Lawrence, Jonas L. Fischer, Salman Ahmed, Dietwald Gruehn, and Susanne Moebus. "Impact of the COVID-19 Lockdown Measures on Noise Levels in Urban Areas—A Pre/during Comparison of Long-Term Sound Pressure Measurements in the Ruhr Area, Germany." International Journal of Environmental Research and Public Health 18, no. 9 (April 27, 2021): 4653. http://dx.doi.org/10.3390/ijerph18094653.
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Background: A major source of noise pollution is traffic. In Germany, the SARS-CoV-2 lockdown caused a substantial decrease in mobility, possibly affecting noise levels. The aim is to analyze the effects of the lockdown measures on noise levels in the densely populated Ruhr Area. We focus on the analysis of noise levels before and during lockdown considering different land use types, weekdays, and time of day. Methods: We used data from 22 automatic sound devices of the SALVE (Acoustic Quality and Health in Urban Environments) project, running since 2019 in Bochum, Germany. We performed a pre/during lockdown comparison of A-weighted equivalent continuous sound pressure levels. The study period includes five weeks before and five weeks during the SARS-CoV-2 induced administrative lockdown measures starting on 16 March 2020. We stratified our data by land use category (LUC), days of the week, and daytime. Results: We observed highest noise levels pre-lockdown in the ‘main street’ and ‘commercial areas’ (68.4 ± 6.7 dB resp. 61.0 ± 8.0 dB), while in ‘urban forests’ they were lowest (50.9 ± 6.6 dB). A distinct mean overall noise reduction of 5.1 dB took place, with noise reductions occurring in each LUC. However, the magnitude of noise levels differed considerably between the categories. Weakest noise reductions were found in the ‘main street’ (3.9 dB), and strongest in the ‘urban forest’, ‘green space’, and ‘residential area’ (5.9 dB each). Conclusions: Our results are in line with studies from European cities. Strikingly, all studies report noise reductions of about 5 dB. Aiming at a transformation to a health-promoting urban mobility can be a promising approach to mitigating health risks of noise in cities. Overall, the experiences currently generated by the pandemic offer data for best practices and policies for the development of healthy urban transportation—the effects of a lower traffic and more tranquil world were experienced firsthand by people during this time.
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Domazetovska, Simona, Maja Anachkova, Viktor Gavriloski, Ankica Sokolikj, and Sandra Stojkovska. "The impact of COVID-19 lockdown on the noise pollution: case study in the city of Skopje." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 4 (August 1, 2021): 2087–94. http://dx.doi.org/10.3397/in-2021-2047.
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The lockdown that the city of Skopje has suffered during the months of April to June 2020 in order to control the spread of COVID-19 has significantly changed the acoustic environment in the urban parts of the city. The absence of vehicles, people on the streets and closed restaurants has led to a noise reduction captured by the low-cost wireless sensor network in the City of Skopje. The analysis carried out in this paper show reduction in noise pollution strongly correlated with the population's activity and behavior to the new circumstances. Overall, the sound pressure levels vary around 65 dB; however, some extreme decrease can be noticed, especially during the quarantine weekends. Also, the noise levels were compared between the same time periods during the year of 2019 and 2020, where it can be perceived reduction in the sound level for 36,5% for the day-evening-night noise level indicator (L). Significant variations occur for the indicators L, L, and L, especially during the lockdown weekends.
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Argüelles Díaz, Katia María, Sandra Velarde-Suárez, Jesús Manuel Fernández Oro, and José González Pérez. "Simplified Assessment on the Wind Farm Noise Impact of the E2O Experimental Offshore Station in the Asturian Coast." Energies 13, no. 21 (November 5, 2020): 5788. http://dx.doi.org/10.3390/en13215788.
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This paper presents a preliminary evaluation of the acoustic impact of an offshore experimental wind farm (E2O), conceived and planned to be installed in Asturias on Spain’s northwest coast. A simplified assessment of the wind turbines’ noise impact at an offshore platform was performed numerically, adapting commercial software for room acoustics to this particular application. As a result, the sound levels at specific receiver sites on the coastline were estimated to select the most convenient level between the two possible locations. Parameters from acoustic emission data of the selected wind turbines were introduced as inputs to the simulation, and the noise propagation in the analyzed domains (for different values of their basic parameters) was simulated. Complementarily, the numerical results were compared to calculations following the ISO 9613-2 standard on sound propagation outdoors for validation purposes, showing good overall agreement. The results revealed that both projected areas under consideration follow the current normative concerning the prescribed acoustic limits, according to the predicted low sound pressure values at the specific considered receiver sites.
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Dirks, Donald D., Jayne B. Ahlstrom, and Laurie S. Eisenberg. "Effects of Probe Insertion Depth on Real Ear Measurements." Otolaryngology–Head and Neck Surgery 110, no. 1 (January 1994): 64–74. http://dx.doi.org/10.1177/019459989411000108.
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The purpose of this article is to provide an overall summary of the role probe insertion depth has on real ear measurements, and to compare the real ear sound pressure level measured by a probe microphone system, using three methods for positioning the probe in an ear canal. The probe insertion techniques that were compared included: (1) an acoustic method that incorporates use of the quarter-wave antiresonance property of the ear to determine acoustically the location of the probe tube relative to the eardrum in an individual ear; (2) a constant insertion depth method (25 mm from the intratragal notch); and (3) the earmold + 5 mm method, which places the probe 5 mm beyond the tip of the individual's earmold in the canal, thereby avoiding problems associated with the transition region, where sound exits from the bore of the earmold into the larger ear canal. Measurements were obtained for each method at 32 frequencies in the unoccluded ears of 17 subjects. Results indicated that the sound pressure levels measured by the acoustic method were significantly larger than those measured by the other two methods. This result was most evident in subjects with long ear canals (> 25 mm) and at high test frequencies (4.0 to 6.3 kHz). For subjects with short or average length ear canals, the three methods provided essentially equivalent results.
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Hawkins, Anthony D., and Arthur N. Popper. "A sound approach to assessing the impact of underwater noise on marine fishes and invertebrates." ICES Journal of Marine Science 74, no. 3 (December 24, 2016): 635–51. http://dx.doi.org/10.1093/icesjms/fsw205.
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Increasing attention is being paid to the ecological consequences of underwater noise generated by human activities such as shipping and maritime industries including, but not limited to, oil and gas exploration and extraction, sonar systems, dredging and the construction of offshore renewable energy devices. There is particular concern over the extension of these activities into previously undeveloped areas of the oceans, including Polar Regions and areas of coral reef habitat. Most of the concern by regulators and others has focussed upon effects upon marine mammals and other protected species. However, examining the impacts upon the overall ecology of affected habitats is also important as it may be dominated by effects upon the far larger biomasses of fishes and invertebrates, which do not have the same degree of legal protection. Many of these assessments of the impact of noise on fishes and invertebrates have overlooked important issues, including the sensitivity of a substantial proportion of these species to particle motion rather than sound pressure. Attempts have been made to establish sound exposure criteria setting regulatory limits to the levels of noise in terms of effects upon mortality levels, injury to tissues, hearing abilities, behaviour, and physiology. However, such criteria have almost exclusively been developed for marine mammals. Criteria for fishes and invertebrates have often had to be assumed, or they have been derived from poorly designed and controlled studies. Moreover, the metrics employed to describe sounds from different sources have often been inappropriate, especially for fishes, and invertebrates, as they have been based on sound pressure rather than particle motion. In addition, the sound propagation models employed to assess the distances over which effects might occur have seldom been validated by actual measurements and are especially poor at dealing with transmission under shallow water conditions, close to or within the seabed, or at the surface. Finally, impacts on fish and invertebrate populations are often unknown and remain unassessed. This paper considers the problems of assessing the impact of noise upon fishes and invertebrates and the assessment procedures that need to be implemented to protect these animals and the marine ecosystems of which they form an integral part. The paper also suggests directions for future research and planning that, if implemented, will provide for a far better scientific and regulatory basis for dealing with effects of noise on aquatic life.
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de Vos, Rick, Nikolaos M. Papadakis, and Georgios E. Stavroulakis. "Improved Source Characteristics of a Handclap for Acoustic Measurements: Utilization of a Leather Glove." Acoustics 2, no. 4 (November 27, 2020): 803–11. http://dx.doi.org/10.3390/acoustics2040045.
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A handclap is a convenient and easily available source for room acoustic measurements. If used correctly (e.g., application of optimal hand configuration) it can provide usable results for the measurement of acoustic parameters, within an expected deviation. Its biggest drawbacks are the low sound pressure level (especially in the low frequency range) as well as its low repeatability. With this in mind, this paper explores the idea of testing a handclap with a glove in order to assess the effect on its source characteristics. For this purpose, measurements were performed with 12 participants wearing leather gloves. Sound levels were compared with simple handclaps without gloves, and between grouped results (overall A-weighted SPL, octave bands, 1/3 octave bands). Measurements were also performed several times to evaluate the effect on repeatability. Results indicate that the use of leather gloves can increase the sound levels of a handclap by 10 dB and 15 dB in the low frequency ranges (63 Hz and 125 Hz octave bands, respectively). Handclaps with leather gloves also point toward improved repeatability, particularly in the low-frequency part of the frequency spectrum. In conclusion, compared to simple handclaps without gloves, evidence from this study supports the concept that handclaps with leather gloves can be used in engineering practices for improved room acoustic measurements of room impulse response.
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Didier, Madeline, and Gina Jarta. "Occupant noise exposure in a fitness classroom setting." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 2 (August 1, 2021): 4070–78. http://dx.doi.org/10.3397/in-2021-2595.
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Fitness facilities characteristically place an emphasis on the health and wellness of their occupants. Very loud amplified speech and music in group fitness rooms creates energetic spaces at the expense of the health and wellness of participants' hearing. The authors measured spectral sound pressure levels from fitness programs and occupants in over 20 group fitness classes (cycling, dance, strength training, and yoga) at facilities throughout the United States. Measurements occurred over durations varying from 10 minutes to a full hour. Variables considered include class type and the athletic club where the classroom is located. This paper discusses the overall findings from these noise surveys with an emphasis on noise exposure and statistical levels. This paper also includes a discussion of noise management and recommendations for best management practices to help achieve energetic spaces that are protective of hearing health and wellness.
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Brehm, Christoph, Jeffrey A. Housman, and Cetin C. Kiris. "Noise generation mechanisms for a supersonic jet impinging on an inclined plate." Journal of Fluid Mechanics 797 (May 26, 2016): 802–50. http://dx.doi.org/10.1017/jfm.2016.244.
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Noise generation mechanisms for a perfectly expanded supersonic Mach number $M=1.8$ turbulent jet impinging on a $45^{\circ }$ inclined plate are investigated for a Reynolds number of $1.6\times 10^{6}$ employing a large-eddy simulation. Excellent comparisons with experimental acoustic far-field measurements and pressure measurements on the impingement plate are obtained. Two local maxima are identified in the far-field overall sound pressure levels in the $75^{\circ }$ and $120^{\circ }$ observer directions, which are associated with different noise generation mechanisms. The peak frequencies in the spectra with Strouhal numbers of $St=0.2$ for $75^{\circ }$ and $St=0.5$ for $120^{\circ }$ match the experimental measurements. The jet-impingement region generates pressure waves that propagate predominantly in the $120^{\circ }$ observer direction. The noise generation in this region is attributed to vortex stretching and tearing during shear-layer impingement, and shock oscillations that are induced by the motion of downstream convected vortical flow structures. The second peak in the overall sound pressure distribution at $75^{\circ }$ is associated with noise sources located in the wall jet. The noise generation in the wall jet is associated with supersonically convecting large-scale coherent flow structures that also interact with tail shocks in the wall jet causing large localized pressure fluctuations. Strongly coherent flow structures are identified by applying proper orthogonal decomposition (POD) to the unsteady flow field. The frequency characteristics of the most energetic POD modes are distinctly different based on which energy norm is chosen. The most energetic entropy-based POD modes contain a peak frequency of approximately $St=0.4{-}0.6$, while the most energetic turbulent kinetic-energy-based POD modes appear to be dominated by lower-frequency content. The causality method, based on Lighthill’s acoustic analogy, is used to link the acoustic noise signature to the relevant physical mechanisms in the source region. A differentiation is made between the application of normalized and non-normalized cross-correlation functions for noise source identification and characterization.
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Prospathopoulos, John M., and Spyros G. Voutsinas. "Noise Propagation Issues in Wind Energy Applications." Journal of Solar Energy Engineering 127, no. 2 (April 25, 2005): 234–41. http://dx.doi.org/10.1115/1.1862257.
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The prediction of noise emitted from operating wind turbines is important to planners in order to avoid the possibility of surpassing the allowable limits close to residential areas. To this end, the wave equation is solved, taking into account the atmospheric and ground characteristics that affect sound propagation. In the present paper, a ray tracing methodology capable of performing axisymmetric calculations of the sound field around an isolated source is used. The methodology simulates all the main physical mechanisms that influence sound propagation and performs calculations for the whole range of acoustic frequencies. In the case of more sources, a quasi-3D calculation is implemented, superposing the contributions from all sources. Application to single wind turbines is validated with available measurements. The effect of various parameters such as ground impedance, temperature, humidity, turbulence, and wind velocity is investigated for an isolated wind turbine as well as for wind parks. It is shown that ground and atmospheric absorption are important at the low and high frequency ranges, respectively. In flat terrain cases, simple propagation models may also give satisfactory predictions of the overall sound pressure levels. However, in complex terrain cases, the wind velocity and the relief of the topography can significantly affect noise propagation, suggesting the necessity for using sophisticated propagation models, such as the current one.
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Hasheminejad, Seyyed M., and A. Fadavi-Ardakani. "Elasto-acoustic response damping performance of a smart cavity-coupled electro-rheological fluid sandwich panel." Journal of Sandwich Structures & Materials 20, no. 6 (January 17, 2017): 661–91. http://dx.doi.org/10.1177/1099636216673857.
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The transient vibroacoustic response mitigation of a rectangular sandwich panel with an adaptive electro-rheological fluid core layer, and backed by a hard-walled reverberant rectangular parallelepiped acoustic enclosure, is investigated. The problem is analyzed in a multidisciplinary framework that involves the thin sandwich electro-rheological fluid-based plate model, the 3D wave equation for the acoustic enclosure domain, the first-order Kelvin–Voigt viscoelastic model for the electro-rheological fluid core material, the pertinent structure–fluid compatibility relation, and the inherently robust sliding mode control strategy. The generalized Fourier expansion method is utilized to set up the fully coupled system equations in the state–space domain, and the fourth-order Runge-Kutta time marching technique is then utilized to compute both uncontrolled and controlled coupled system responses in three basic external loading configurations. It is found that increasing the cavity depth has a substantial restraining effect on the overall sound pressure response levels, while the electro-rheological fluid-panel displacement response amplitudes experience only moderate reductions. Also, a purely passive electro-rheological fluid-based system is observed not to be very effective for vibroacoustic response suppression of the cavity-coupled structural system, while the overall success of the applied sliding mode control methodology in reasonable reduction of both panel displacement and sound pressure time response amplitudes is demonstrated. Furthermore, the control system authority with regard to the acoustic cavity pressure (panel displacement) is found to moderately (slightly) decrease as the cavity depth increases. Limiting cases are considered and accuracy of the suggested analytical model is checked against the output of an FEM package as well as with the accessible literature results. Moreover, the main components of a prospective experimental platform for verifying the performance of proposed vibroacoustic control system are briefly described.
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Kamliya Jawahar, Hasan, Yujing Lin, and Mark Savill. "Large eddy simulation of airfoil self-noise using OpenFOAM." Aircraft Engineering and Aerospace Technology 90, no. 1 (January 2, 2018): 126–33. http://dx.doi.org/10.1108/aeat-05-2015-0130.
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Purpose The purpose of this paper is to investigate airfoil self-noise generation and propagation by using a hybrid method based on the large-eddy simulation (LES) approach and Curle’s acoustic analogy as implemented in OpenFOAM. Design/methodology/approach Large-eddy simulation of near-field flow over a NACA6512-63 airfoil at zero angle of attack with a boundary layer trip at Rec = 1.9 × 105 has been carried out using the OpenFOAM® computational fluid dynamics (CFD) code. Calculated flow results are compared with published experimental data. The LES includes the wind tunnel installation effects by using appropriate inflow boundary conditions obtained from a RANS κ – ω SST model computation of the whole wind tunnel domain. Far-field noise prediction was achieved by an integral method based on Curle’s acoustic analogy. The predicted sound pressure levels are validated against the experimental data at various frequency ranges. Findings The numerical results presented in this paper show that the flow features around a NACA6512-63 airfoil have been correctly captured in OpenFOAM LES calculations. The mean surface pressure distributions and the local pressure peaks for the step trip setup agree very well with the experimental measurements. Aeroacoustic prediction using Curle’s analogy shows an overall agreement with the experimental data. The sound pressure level-frequency spectral analysis produces very similar data at low to medium frequency, whereas the experimentally observed levels are slightly over predicted at a higher frequency range. Practical implications This study has achieved and evaluated an alternative aeroacoustic simulation method based on the combination of LES with a simple Smagorinsky SGS model and Curle’s analogy, as implemented in the OpenFOAM CFD code. The unsteady velocity/pressure source data produced can be used for any simpler analytically based far-field noise prediction scheme. Originality/value A complete integration of the LES and Curle’s acoustic analogy for aeroacoustic simulations has been achieved in OpenFOAM. The capability and accuracy of the hybrid method are fully evaluated for high-camber airfoil self-noise predictions. Wind tunnel installation effects have been incorporated properly into the LES.
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Thompson, Paul M., Kate L. Brookes, Isla M. Graham, Tim R. Barton, Keith Needham, Gareth Bradbury, and Nathan D. Merchant. "Short-term disturbance by a commercial two-dimensional seismic survey does not lead to long-term displacement of harbour porpoises." Proceedings of the Royal Society B: Biological Sciences 280, no. 1771 (November 22, 2013): 20132001. http://dx.doi.org/10.1098/rspb.2013.2001.
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Assessments of the impact of offshore energy developments are constrained because it is not known whether fine-scale behavioural responses to noise lead to broader-scale displacement of protected small cetaceans. We used passive acoustic monitoring and digital aerial surveys to study changes in the occurrence of harbour porpoises across a 2000 km 2 study area during a commercial two-dimensional seismic survey in the North Sea. Acoustic and visual data provided evidence of group responses to airgun noise from the 470 cu inch array over ranges of 5–10 km, at received peak-to-peak sound pressure levels of 165–172 dB re 1 µPa and sound exposure levels (SELs) of 145–151 dB re 1 µPa 2 s −1 . However, animals were typically detected again at affected sites within a few hours, and the level of response declined through the 10 day survey. Overall, acoustic detections decreased significantly during the survey period in the impact area compared with a control area, but this effect was small in relation to natural variation. These results demonstrate that prolonged seismic survey noise did not lead to broader-scale displacement into suboptimal or higher-risk habitats, and suggest that impact assessments should focus on sublethal effects resulting from changes in foraging performance of animals within affected sites.
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Woo, Sangbeom, and Andrea Vacca. "Experimental Characterization and Evaluation of the Vibroacoustic Field of Hydraulic Pumps: The Case of an External Gear Pump." Energies 13, no. 24 (December 16, 2020): 6639. http://dx.doi.org/10.3390/en13246639.
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This paper presents the experimental characterization of the vibroacoustic fields and the evaluation of noise performances of hydraulic pumps. Research on hydraulic pump noise has traditionally focused on the fluid-borne noise sources, and very often the analyses of vibration and noise have been performed focusing on a few local points. This trend results in the lack of investigation on the overall behaviors of vibroacoustic fields of hydraulic pumps, and it has been one of the obstacles to understand the complete mechanisms of noise generation. Moreover, despite the existence of the ISO standards for the determination of noise levels, diverse metrics have been used for the evaluation of noise performances of the pumps, but the adequacy of these metrics has not been carefully examined. In this respect, this paper aims at introducing a way to characterize and interpret the measured vibroacoustic field and providing proper methods which are also capable of applying the ISO standards for the fair assessment of pump noise performances. For the characterization of the vibroacoustic field, operational deflection shapes (ODS) and corresponding radiated sound fields are visualized at harmonics of the pumping frequency by using a spectral analysis. Observations are made regarding the motions of the pump and its mounting plate and the resultant radiated noise, depending on the frequency, as well as their correlation. A numerical analysis using the Rayleigh integral equation is also performed to further investigate the contribution of the mounting plate motion on the noise radiation. For the evaluation of noise performance, two different units are tested at multiple operating conditions, and comparisons are made based on their measured sound power levels (SWLs) and sound pressure levels (SPLs). The results emphasize the importance of SWL measurement for the fair noise performance evaluation, and the two methods are proposed as practices to determine the minimum number of measurement points for practicability and to have reliable sound power determination for hydraulic pumps.
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Beltman, Willem, Hector Cordourier, and Paulo Lopez Meyer. "Hearing protection and communication in high noise environments using vibration sensing and neural network voice transformation." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 1 (August 1, 2021): 5027–37. http://dx.doi.org/10.3397/in-2021-2925.
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In the United States alone, there are more than 9 million workers who are exposed to high levels of noise (> 85 dBA) that require hearing protection. Not only is there a risk of hearing damage due to these high noise levels, but it also prevents communication between people, leading to significant safety risks, including people not using hearing protection because of the desire to communicate. Workers in such high noise environments typically also wear safety glasses. This paper outlines an integrated system with safety glasses, hearing protection, and communication elements, using vibration sensing technology and a neural network based voice transformation routine. Data was collected to train the neural network based voice transformation. Recordings were made under various representative noise conditions, with some well exceeding sound pressure levels of 93 dBA, and Signal to Noise Ratios were extracted. In addition, experiments were conducted according to a modified ITU P.835 approach to determine intelligibility, naturalness and overall quality. The results demonstrate that with this approach, speech can be clearly understood in such high noise environments with this approach.
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Redel-Macías, María Dolores, Pilar Aparicio-Martinez, Sara Pinzi, Pedro Arezes, and Antonio José Cubero-Atienza. "Monitoring Sound and Its Perception during the Lockdown and De-Escalation of COVID-19 Pandemic: A Spanish Study." International Journal of Environmental Research and Public Health 18, no. 7 (March 25, 2021): 3392. http://dx.doi.org/10.3390/ijerph18073392.
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The lockdown measures in Spain due to the SARS-CoV-2 or COVID-19 (Coronavirus disease 2019) pandemic from 13 March to 21 June 2020 had extensive social and environmental implications. This study aims to understand how the measures of lockdown have influenced noise levels, as well as people’s perception of sound quality before and after lockdown, including de-escalation. For this purpose, an online survey was carried out. Moreover, the noise linked to the Global Positioning System (GPS) position of each individual respondent was recorded aiming to correlate the noise level with the result of the survey. An average reduction of over 30 dB was observed compared with the sound pressure level before lockdown. Furthermore, it was found that the loudness parameter, together with the overall level, increased as the country started relaxing restrictions. Additionally, results showed that the perception of noise quality changed depending on the phase of de-escalation (p < 0.01), the type of property (p < 0.05), and the outside noise (p < 0.01). Moreover, noise annoyance was determined considering age (p < 0.01), gender (p < 0.05), type of property (p < 0.001), and home refurbishment (p < 0.05). It may be concluded that the most important measure to decrease noise levels is the reduction of traffic noise, through using eco-friendly public transportation or bicycles and limiting nightlife hours.
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Thomas, Megan L. A., Denis Fitzpatrick, Ryan McCreery, and Kristen L. Janky. "Big Stimulus, Little Ears: Safety in Administering Vestibular-Evoked Myogenic Potentials in Children." Journal of the American Academy of Audiology 28, no. 05 (May 2017): 395–403. http://dx.doi.org/10.3766/jaaa.15097.
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Background: Cervical and ocular vestibular-evoked myogenic potentials (VEMPs) have become common clinical vestibular assessments. However, VEMP testing requires high intensity stimuli, raising concerns regarding safety with children, where sound pressure levels may be higher due to their smaller ear canal volumes. Purpose: The purpose of this study was to estimate the range of peak-to-peak equivalent sound pressure levels (peSPLs) in child and adult ears in response to high intensity stimuli (i.e., 100 dB normal hearing level [nHL]) commonly used for VEMP testing and make a determination of whether acoustic stimuli levels with VEMP testing are safe for use in children. Research Design: Prospective experimental. Study Sample: Ten children (4–6 years) and ten young adults (24–35 years) with normal hearing sensitivity and middle ear function participated in the study. Data Collection and Analysis: Probe microphone peSPL measurements of clicks and 500 Hz tonebursts (TBs) were recorded in tubes of small, medium, and large diameter, and in a Brüel & Kjær Ear Simulator Type 4157 to assess for linearity of the stimulus at high levels. The different diameter tubes were used to approximate the range of cross-sectional areas in infant, child, and adult ears, respectively. Equivalent ear canal volume and peSPL measurements were then recorded in child and adult ears. Lower intensity levels were used in the participant’s ears to limit exposure to high intensity sound. The peSPL measurements in participant ears were extrapolated using predictions from linear mixed models to determine if equivalent ear canal volume significantly contributed to overall peSPL and to estimate the mean and 95% confidence intervals of peSPLs in child and adult ears when high intensity stimulus levels (100 dB nHL) are used for VEMP testing without exposing subjects to high-intensity stimuli. Results: Measurements from the coupler and tubes suggested: 1) each stimuli was linear, 2) there were no distortions or nonlinearities at high levels, and 3) peSPL increased with decreased tube diameter. Measurements in participant ears suggested: 1) peSPL was approximately 3 dB larger in child compared to adult ears, and 2) peSPL was larger in response to clicks compared to 500 Hz TBs. The model predicted the following 95% confidence interval for a 100 dB nHL click: 127–136.5 dB peSPL in adult ears and 128.7–138.2 dB peSPL in child ears. The model predicted the following 95% confidence interval for a 100 dB nHL 500 Hz TB stimulus: 122.2–128.2 dB peSPL in adult ears and 124.8–130.8 dB peSPL in child ears. Conclusions: Our findings suggest that 1) when completing VEMP testing, the stimulus is approximately 3 dB higher in a child’s ear, 2) a 500 Hz TB is recommended over a click as it has lower peSPL compared to the click, and 3) both duration and intensity should be considered when choosing VEMP stimuli. Calculating the total sound energy exposure for your chosen stimuli is recommended as it accounts for both duration and intensity. When using this calculation for children, consider adding 3 dB to the stimulus level.
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Pawlaczyk-Łuszczyńska, Małgorzata, Małgorzata Zamojska, Adam Dudarewicz, and Kamil Zaborowski. "Noise-Induced Hearing Loss in Professional Orchestral Musicians." Archives of Acoustics 38, no. 2 (June 1, 2013): 223–34. http://dx.doi.org/10.2478/aoa-2013-0027.
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Abstract The overall purpose of this study was to assess hearing status in professional orchestral musicians. Standard pure-tone audiometry (PTA) and transient-evoked otoacoustic emissions (TEOAEs) were per- formed in 126 orchestral musicians. Occupational and non-occupational risk factors for noise-induced hearing loss (NIHL) were identified in questionnaire inquiry. Data on sound pressure levels produced by various groups of instruments were also collected and analyzed. Measured hearing threshold levels (HTLs) were compared with the theoretical predictions calculated according to ISO 1999 (1990). Musicians were exposed to excessive sound at weekly noise exposure levels of for 81-100 dB (mean: 86.6±4.0 dB) for 5-48 years (mean: 24.0±10.7 years). Most of them (95%) had hearing corresponds to grade 0 of hearing impairment (mean hearing threshold level at 500, 1000, 2000 and 4000 Hz lower than 25 dB). However, high frequency notched audiograms typical for noise-induced hearing loss were found in 35% of cases. Simultaneously, about 35% of audiograms showed typical for NIHL high frequency notches (mainly occurring at 6000 Hz). When analyzing the impact of age, gender and noise exposure on hearing test results both PTA and TEOAE consistently showed better hearing in females vs. males, younger vs. older musicians. But higher exposure to orchestral noise was not associated with poorer hearing tests results. The musician’s audiometric hearing threshold levels were poorer than equivalent non-noise-exposed population and better (at 3000 and 4000 Hz) than expected for noise-exposed population according to ISO 1999 (1990). Thus, music impairs hearing of orchestral musicians, but less than expected from noise exposure.
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Handegard, Nils Olav, Alex De Robertis, Guillaume Rieucau, Kevin Boswell, and Gavin J. Macaulay. "The reaction of a captive herring school to playbacks of a noise-reduced and a conventional research vessel." Canadian Journal of Fisheries and Aquatic Sciences 72, no. 4 (April 2015): 491–99. http://dx.doi.org/10.1139/cjfas-2014-0257.
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Fish avoidance of vessels can bias fisheries-independent surveys. To understand these biases, recordings of underwater radiated vessel noise from a noise-reduced and a conventional research vessel were played back at the same sound pressure levels (SPL) as experienced in situ to Atlantic herring (Clupea harengus) in a net pen at two different densities. The noise-reduced vessel recording was also scaled to the same SPL as the conventional vessel to test if characteristics other than SPL affected the reactions. Overall, only weak reactions were observed, but reactions were stronger in the low-density school, in the middle of the pen, and for the scaled silent vessel compared with the conventional vessel. These observations may be attributable to the lack of low frequencies (<50 Hz) in the playbacks, differential motivation for reaction driven by fish density, higher low-frequency noise in the middle of the pen (but lower overall SPL), and characteristics other than SPL. These results call into question the use of SPL as a proxy for fish reaction to vessels as used in standards for construction of research vessels.
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Constantinescu, Gabriella A., Deborah G. Theodoros, Trevor G. Russell, Elizabeth C. Ward, Stephen J. Wilson, and Richard Wootton. "Home-based speech treatment for Parkinson's disease delivered remotely: a case report." Journal of Telemedicine and Telecare 16, no. 2 (December 11, 2009): 100–104. http://dx.doi.org/10.1258/jtt.2009.090306.
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We investigated the validity and feasibility of online delivery of the Lee Silverman Voice Treatment (LSVT) for the treatment of the speech disorder of a patient with idiopathic Parkinson's disease. The treatment was delivered in 16 sessions to the participant's home, 90 km from the speech language pathologist. A PC-based videoconferencing system was used, operating at 128 kbit/s over the public telecommunications network. The patient achieved substantial improvements in vocal sound pressure levels during sustained vowel phonation (6.13 dB), reading (12.28 dB) and conversational monologue (11.32 dB). There were improvements in the duration of sustained vowel phonation (4 s). Improvements were also perceived in the degree of breathiness and roughness in the voice, and in overall speech intelligibility in conversation. The patient was very satisfied with the audio and video quality of the conferencing, and with the online treatment overall. He reported a preference for online sessions for the future management of his condition, rather than face-to-face treatment. Remote LSVT delivery was found to be feasible and effective.
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Zou, Chun-Ping, Duan-Shi Chen, and Hong-Xing Hua. "Investigation of Ship Structural Vibration and Underwater Radiation Noise." Journal of Ship Research 47, no. 04 (December 1, 2003): 275–89. http://dx.doi.org/10.5957/jsr.2003.47.4.275.
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Underwater radiation noise is a very important factor for most ships, such as fishing boats, warships, and so forth. The magnitude of its energy depends on the vibration of the hull in contact with water. The vibration of the hull caused by the power plant, while the vessel is cruising, is the dominant source of underwater radiation noise, which is the subject of our investigation. In this paper, the coupled finite element/boundary element method is used to investigate ship structural vibration and underwater radiation noise. The finite element method (FEM) is employed to analyze modes and vibration responses of an entire ship for different kinds of excitations in consideration of fluid-structure interaction. The boundary element method (BEM) is used to analyze the underwater radiation noise. A FEM model is first constructed by using 30 geometric parameters and five kinds of finite elements. Then, the reduced matrix method is used to eliminate the local modes in order to obtain the overall bending and torsional modes of the ship. Last, vibration displacements of the hull are treated as the velocity boundary condition of BEM to calculate underwater radiation noise. Numerical results show thatthe calculated sound-pressure levels of underwater radiation noise are in a good agreement with experimentally measured results;although the vibration isolator is used, the propulsion diesel engine is the dominant source of the underwater radiation noise among all machines in the engine room and the maximum sound-pressure levels increase as the sailing speed of the ship increases;the underwater radiation noise of the ship with gearbox excitation is greater than that of the ship with diesel generator set excitation, which should be noticed by the ship designers during the design stage.
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Sharma, Nitin, Trupti Ranjan Mahapatra, and Subrata Kumar Panda. "Numerical analysis of acoustic radiation properties of laminated composite flat panel in thermal environment: A higher-order finite-boundary element approach." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 18 (November 3, 2017): 3235–49. http://dx.doi.org/10.1177/0954406217735866.
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In this article, the vibration-induced acoustic responses of laminated composite flat panels subjected to harmonic mechanical excitation under uniform temperature load are investigated numerically. The natural frequencies alongside corresponding modes of the flat panels resting on an infinite rigid baffle are obtained by using finite element method in the framework of the higher-order shear deformation theory. A coupled finite and boundary element formulation is then employed to acquire the acoustic responses. The governing equation for the sound radiaiton from the vibrating structures is derived by solving the Helmholtz wave equation. The vibration and acoustic responses are computed by using the present scheme via an in-house computer code developed in MATLAB environment. In order to avoid any excess thermal loading conditions first, the critical buckling temperature of the panel structure is obtained and authenticated with the benchmark values. Further, the sound power levels for isotropic and laminated composite panels are computed using the present scheme and validated with the existing results in the published literature. Finally, the influence of lamination scheme, support conditions and modular ratio on the acoustic radiation behavior of laminated composite flat panels in an elevated thermal environment is studied through various numerical examples. The thermal load is found to have substantial influence on the stiffness of the panels and the peaks in the free vibration responses tend to shift to lower frequencies for higher temperatures. It is also inferred that the panels radiate less efficiently whereas the overall sound pressure level is found to follow an increasing trend with increasing temperature.
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Kügler, A., MO Lammers, EJ Zang, MB Kaplan, and TA Mooney. "Fluctuations in Hawaii’s humpback whale Megaptera novaeangliae population inferred from male song chorusing off Maui." Endangered Species Research 43 (December 17, 2020): 421–34. http://dx.doi.org/10.3354/esr01080.
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Approximately half of the North Pacific humpback whale Megaptera novaeangliae stock visits the shallow waters of the main Hawaiian Islands seasonally. Within this breeding area, mature males produce an elaborate acoustic display known as song, which becomes the dominant source of ambient underwater sound between December and April. Following reports of unusually low whale numbers that began in 2015/16, we examined song chorusing recorded through long-term passive acoustic monitoring at 6 sites off Maui as a proxy for relative whale abundance between 2014 and 2019. Daily root-mean-square sound pressure levels (RMS SPLs) were calculated to compare variations in low-frequency acoustic energy (0-1.5 kHz). After 2014/15, the overall RMS SPLs decreased between 5.6 and 9.7 dB re 1 µPa2 during the peak of whale season (February and March), reducing ambient acoustic energy from chorusing by over 50%. This change in song levels co-occurred with a broad-scale oceanic heat wave in the northeast Pacific termed the ‘Blob,’ a major El Niño event in the North Pacific, and a warming period in the Pacific Decadal Oscillation cycle. Although it remains unclear whether our observations reflect a decrease in population size, a change in migration patterns, a shift in distribution to other areas, a change in the behavior of males, or some combination of these, our results indicate that continued monitoring and further studies of humpback whales throughout the North Pacific are warranted to better understand the fluctuations occurring in this recently recovered population and other populations that continue to be endangered or threatened.
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Zhou, Gideon. "Three Decades of Public Expenditure Management in Zimbabwe." Journal of Public Administration and Governance 2, no. 3 (July 28, 2012): 33. http://dx.doi.org/10.5296/jpag.v2i3.2098.
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Sound public expenditure management forms the bedrock of public administration. It facilitates producence, efficiency, transparency and accountability in expenditure processes at various levels of government. This serves as a long term barricade aginst debt trap. This article responds to these fundamental concerns by examining the nature, processes and challenges of public expenditure management in Zimbabwe. Reviews of expenditure management systems in Zimbabwe show general consistence with those in Anglophone Africa. Ministries of finance, working closely with spending ministries, Accounting Officers, Public Accounts Committees of Parliament, Auditor Generals and internal auditors-constitute key players in the public expenditure management process. Notwithstanding this, overall expenditure over the decades remained sticky downwards due to inflationary pressures, unbudgeted expenditures and weak expenditure management systems. Robust mesaures should be put in place to institutionalise a culture of compliance with extant expenditure management frameworks at both the macro and micro levels of government.
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López, Juan Manuel, Jesús Alonso, César Asensio, Ignacio Pavón, Luis Gascó, and Guillermo de Arcas. "A Digital Signal Processor Based Acoustic Sensor for Outdoor Noise Monitoring in Smart Cities." Sensors 20, no. 3 (January 22, 2020): 605. http://dx.doi.org/10.3390/s20030605.
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Presently, large cities have significant problems with noise pollution due to human activity. Transportation, economic activities, and leisure activities have an important impact on noise pollution. Acoustic noise monitoring must be done with equipment of high quality. Thus, long-term noise monitoring is a high-cost activity for administrations. For this reason, new alternative technological solutions are being used to reduce the costs of measurement instruments. This article presents a design for a versatile electronic device to measure outdoor noise. This device has been designed according to the technical standards for this type of instrument, which impose strict requirements on both the design and the quality of the device’s measurements. This instrument has been designed under the original equipment manufacturer (OEM) concept, so the microphone–electronics set can be used as a sensor that can be connected to any microprocessor-based device, and therefore can be easily attached to a monitoring network. To validate the instrument’s design, the device has been tested following the regulations of the calibration laboratories for sound level meters (SLM). These tests allowed us to evaluate the behavior of the electronics and the microphone, obtaining different results for these two elements. The results show that the electronics and algorithms implemented fully fit within the requirements of type 1 noise measurement instruments. However, the use of an electret microphone reduces the technical features of the designed instrument, which can only fully fit the requirements of type 2 noise measurement instruments. This situation shows that the microphone is a key element in this kind of instrument and an important element in the overall price. To test the instrument’s quality and show how it can be used for monitoring noise in smart wireless acoustic sensor networks, the designed equipment was connected to a commercial microprocessor board and inserted into the infrastructure of an existing outdoor monitoring network. This allowed us to deploy a low-cost sub-network in the city of Málaga (Spain) to analyze the noise of conflict areas due to high levels of leisure noise. The results obtained with this equipment are also shown. It has been verified that this equipment meets the similar requirements to those obtained for type 2 instruments for measuring outdoor noise. The designed equipment is a two-channel instrument, that simultaneously measures, in real time, 86 sound noise parameters for each channel, such as the equivalent continuous sound level (Leq) (with Z, C, and A frequency weighting), the peak level (with Z, C, and A frequency weighting), the maximum and minimum levels (with Z, C, and A frequency weighting), and the impulse, fast, and slow time weighting; seven percentiles (1%, 5%, 10%, 50%, 90%, 95%, and 99%); as well as continuous equivalent sound pressure levels in the one-third octave and octave frequency bands.
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Bourikas, Leonidas, Stephanie Gauthier, Nicholas Khor Song En, and Peiyao Xiong. "Effect of Thermal, Acoustic and Air Quality Perception Interactions on the Comfort and Satisfaction of People in Office Buildings." Energies 14, no. 2 (January 9, 2021): 333. http://dx.doi.org/10.3390/en14020333.
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Current research on human comfort has identified a gap in the investigation of multi-domain perception interactions. There is a lack of understanding the interrelationships of different physio-socio-psychological factors and the manifestation of their contextual interactions into cross-modal comfort perception. In that direction, this study used data from a post occupancy evaluation survey (n = 26), two longitudinal comfort studies (n = 1079 and n = 52) and concurrent measurements of indoor environmental quality factors (one building) to assess the effect of thermal, acoustic and air quality perception interactions on comfort and satisfaction of occupants in three mixed-mode university office buildings. The study concluded that thermal sensation (TSV) is associated with both air quality (ASV) and noise perception (NSV). The crossed effect of the interaction of air quality and noise perception on thermal sensation was not evident. The key finding was the significant correlation of operative temperature (Top) with TSV as expected, but also with noise perception and overall acoustic comfort. Regarding the crossed main effects on thermal sensation, a significant effect was found for the interactions of (1) Top and (2) sound pressure levels (SPL30) with air quality perception respectively. Most importantly, this study has highlighted the importance of air quality perception in achieving occupants’ comfort and satisfaction with office space.
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Norrix, Linda W., Dianne Van Tasell, Jessie Ross, Frances P. Harris, and James Dean. "Modeling the Influence of Acoustic Coupling of Hearing Aids on FM Signal-to-Noise Ratio." American Journal of Audiology 24, no. 2 (June 2015): 178–87. http://dx.doi.org/10.1044/2015_aja-14-0035.
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Purpose A model was developed to examine variables that influence signal-to-noise ratio (SNR) at the tympanic membrane (TM) when using a hearing aid (HA) and frequency modulated (FM) system. The model was used to explore how HA coupling influences SNR. Method To generate the model, HA output was measured in a coupler. Known coupler to real-ear transformations and known values for vent (gain) loss as a function of coupling were also used. The model was verified by measuring sound pressure level (SPL) at the TM in 6 ears. Results The model predicts similar overall SNRs at the TM regardless of coupling method when HA and FM microphones are active. The primary difference in SNR is in the low frequencies and depends on the amount of low frequency insertion gain and the noise levels at the HA and FM microphones. Conclusions A model was developed to explore how complex variables contribute to SNR at the TM. One variable, HA coupling, is predicted to have only a minimal effect on SNR at the TM when there is HA gain. Further studies will be needed to assess the real-world effectiveness of an FM system coupled to an open- versus closed-fit HA.
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Bourikas, Leonidas, Stephanie Gauthier, Nicholas Khor Song En, and Peiyao Xiong. "Effect of Thermal, Acoustic and Air Quality Perception Interactions on the Comfort and Satisfaction of People in Office Buildings." Energies 14, no. 2 (January 9, 2021): 333. http://dx.doi.org/10.3390/en14020333.
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Current research on human comfort has identified a gap in the investigation of multi-domain perception interactions. There is a lack of understanding the interrelationships of different physio-socio-psychological factors and the manifestation of their contextual interactions into cross-modal comfort perception. In that direction, this study used data from a post occupancy evaluation survey (n = 26), two longitudinal comfort studies (n = 1079 and n = 52) and concurrent measurements of indoor environmental quality factors (one building) to assess the effect of thermal, acoustic and air quality perception interactions on comfort and satisfaction of occupants in three mixed-mode university office buildings. The study concluded that thermal sensation (TSV) is associated with both air quality (ASV) and noise perception (NSV). The crossed effect of the interaction of air quality and noise perception on thermal sensation was not evident. The key finding was the significant correlation of operative temperature (Top) with TSV as expected, but also with noise perception and overall acoustic comfort. Regarding the crossed main effects on thermal sensation, a significant effect was found for the interactions of (1) Top and (2) sound pressure levels (SPL30) with air quality perception respectively. Most importantly, this study has highlighted the importance of air quality perception in achieving occupants’ comfort and satisfaction with office space.
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KROTHAPALLI, A., E. RAJKUPERAN, F. ALVI, and L. LOURENCO. "Flow field and noise characteristics of a supersonic impinging jet." Journal of Fluid Mechanics 392 (August 10, 1999): 155–81. http://dx.doi.org/10.1017/s0022112099005406.
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This paper describes the results of a study examining the flow and acoustic characteristics of an axisymmetric supersonic jet issuing from a sonic and a Mach 1.5 converging–diverging (C–D) nozzle and impinging on a ground plane. Emphasis is placed on the Mach 1.5 nozzle with the sonic nozzle used mainly for comparison. A large-diameter circular plate was attached at the nozzle exit to measure the forces generated on the plate owing to jet impingement. The experimental results described in this paper include lift loss, particle image velocimetry (PIV) and acoustic measurements. Suckdown forces as high as 60% of the primary jet thrust were measured when the ground plane was very close to the jet exit. The PIV measurements were used to explain the increase in suckdown forces due to high entrainment velocities. The self-sustained oscillatory frequencies of the impinging jet were predicted using a feedback loop that uses the measured convection velocities of the large-scale coherent vortical structures in the jet shear layer. Nearfield acoustic measurements indicate that the presence of the ground plane increases the overall sound pressure levels (OASPL) by approximately 8 dB relative to a corresponding free jet. For moderately underexpanded jets, the influence of the shock cells on the important flow features was found to be negligible except for close proximity of the ground plane.
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NIE, RUI, JINHAO QIU, HONGLI JI, and DAWEI LI. "AERODYNAMIC CHARACTERISTIC OF THE ACTIVE COMPLIANT TRAILING EDGE CONCEPT." International Journal of Modern Physics: Conference Series 42 (January 2016): 1660173. http://dx.doi.org/10.1142/s2010194516601733.
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This paper introduces a novel Morphing Wing structure known as the Active Compliant Trailing Edge (ACTE). ACTE structures are designed using the concept of “distributed compliance” and wing skins of ACTE are fabricated from high-strength fiberglass composites laminates. Through the relative sliding between upper and lower wing skins which are connected by a linear guide pairs, the wing is able to achieve a large continuous deformation. In order to present an investigation about aerodynamics and noise characteristics of ACTE, a series of 2D airfoil analyses are established. The aerodynamic characteristics between ACTE and conventional deflection airfoil are analyzed and compared, and the impacts of different ACTE structure design parameters on aerodynamic characteristics are discussed. The airfoils mentioned above include two types (NACA0012 and NACA64A005.92). The computing results demonstrate that: compared with the conventional plane flap airfoil, the morphing wing using ACTE structures has the capability to improve aerodynamic characteristic and flow separation characteristic. In order to study the noise level of ACTE, flow field analysis using LES model is done to provide noise source data, and then the FW-H method is used to get the far field noise levels. The simulation results show that: compared with the conventional flap/aileron airfoil, the ACTE configuration is better to suppress the flow separation and lower the overall sound pressure level.
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Roth, Travis S., David P. Beason, T. Bradley Clay, E. Lyle Cain, and Jeffrey R. Dugas. "The Effect of Ulnar Collateral Ligament Repair With Internal Brace Augmentation on Articular Contact Mechanics: A Cadaveric Study." Orthopaedic Journal of Sports Medicine 9, no. 4 (April 1, 2021): 232596712110010. http://dx.doi.org/10.1177/23259671211001069.
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Background: There has been renewed interest in ulnar collateral ligament (UCL) repair in throwing athletes because of a greater understanding of UCL injuries, improvement in ligament repair technology, and potentially expedited rehabilitation time and return to play relative to UCL reconstruction. Purpose: To evaluate elbow articular contact and overall joint torque after UCL reconstruction and repair augmented with a collagen-coated fiber tape, InternalBrace. Study Design: Controlled laboratory study. Methods: Ten matched pairs of cadaveric arms (mean age, 41 ± 11 years) were dissected to expose the UCL. Each specimen was secured into a custom test fixture at 90°, and 1 specimen from each pair underwent either a modified Jobe UCL reconstruction or UCL repair with InternalBrace. Each specimen underwent 10 cycles of elbow valgus angular displacement between 0° and 5° at a rate of 1 deg/s in the intact state, after UCL avulsion, and then after UCL reconstruction or repair. Articular contact mechanics and overall joint torque and stiffness were recorded. Results: Contact mechanics of reconstructed and repaired specimens were not significantly different. Both reconstruction and repair procedures returned the overall resistance of the joint to valgus torsion to near-intact levels. UCL repair tended to restore joint torque more closely to the intact state than did reconstruction, given that reconstruction showed a nonsignificant trend toward lower torque than the intact state ( P = .07). Conclusion: Neither UCL reconstruction nor UCL repair with InternalBrace overconstrained the elbow joint, as both groups had similar contact pressures compared with the native joint. Both procedures also restored elbow joint torque and stiffness to levels not statistically different from the intact state. Clinical Relevance: Given the sound biomechanical properties of UCL repair with InternalBrace, it may have a significant role as treatment for UCL injuries.
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Butaeva, S. G., A. S. Ametov, A. V. Bugrov, and V. V. Dolgov. "Glycemic variability and oxidative stress in patients with type 2 diabetes mellitus during combined glucose-lowering therapy." Terapevticheskii arkhiv 89, no. 10 (October 15, 2017): 36–39. http://dx.doi.org/10.17116/terarkh2017891036-39.
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Aim. To evaluate the impact of intensified glucose-lowering therapy on carbohydrate metabolic indicator, such as glycated hemoglobin, fasting blood glucose level (BGL) (FBGL), postprandial BGL (PBGL), and glycemic variability (GV) in patients with type 2 diabetes mellitus (T2DM) during metformin monotherapy before and 3 months after therapy intensification. Subjects and methods. The investigation enrolled 51 patients with T2DM treated with metformin 1000 mg twice daily, who failed to achieve satisfactory glycemic control. During randomization, the treatment was intensified by addition of sitagliptin 100 mg/day in Group 1 (n=25) or gliclazide MB 60 mg/day in Group 2 (n=26). Before and 3 months after the treatment, carbohydrate metabolic indicators were investigated, 24-hour BGL monitoring (continuous glucose monitoring system (GMS)) was performed, and the body’s antioxidant status was examined by determining the total antioxidant capacity of blood plasma (overall sound pressure levels (OASPL)). Results. During 3-month treatment, Group 1 had a significantly reduced FBGL compared to that before the therapy; in Group 2 this index did not change significantly. Both study groups showed a significant decrease in PBGL and glycated hemoglobin (HbA1c). The mean amplitude of glycemic excursion (MAGE) was significantly decreased in the sitagliptin intensification group. In both groups, the standard deviation (SD) reduced significantly by 26% in Group 1 and by 38% in Group 2. Both groups also displayed a significant increase in blood OASPL (p
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Nair, R. B., and S. Yavuzkurt. "Modeling Sulfur Dioxide Capture in a Pulverized Coal Combustor." Journal of Engineering for Gas Turbines and Power 119, no. 2 (April 1, 1997): 291–97. http://dx.doi.org/10.1115/1.2815574.
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The formation and capture of sulfur dioxide in a pulverized coal combustor is investigated. A two-dimensional, steady, axisymmetric code, PCGC-2 (Pulverized Coal Gasification and Combustion—two Dimensional), originally developed at Brigham Young University, has been used to simulate combustion of the pulverized coal. This paper represents part of a project to investigate simultaneously enhancing sulfur capture and particulate agglomeration in combustor effluents. Results from the code have been compared to experimental data obtained from MTCI’s (Manufacturing Technology and Conversion International) test pulse combustor, which generates sound pressure levels of ~180 dB. The overall goal behind the pulse combustor program at MTCI is to develop combustors for stationary gas turbines that use relatively inexpensive coal-based fuels. This study attempts to model the capture of sulfur dioxide when injected into a pulse combustor firing micronized coal. While this work does not presume to model the complex gas flow-field generated by the pulsating flow, the effects of the acoustic field are expressed by increased heat and mass transfer to the particles (coal/sorbent) in question. A comprehensive calcination-sintering-sulfation model for single particles was used to model the capture of sulfur dioxide by limestone sorbent. Processes controlling sulfation are external heat and mass transfer, pore diffusion, diffusion through the product layer of CaSO4, sintering, and calcination. The model was incorporated into the PCGC-2 program. Comparisons of exit concentrations of SO2 showed a fairly good agreement (within ~10 percent) with the experimental results from MTCI.
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Barsties, Ben, Rudi Verfaillie, Nelson Roy, and Youri Maryn. "Do body mass index and fat volume influence vocal quality, phonatory range, and aerodynamics in females?" CoDAS 25, no. 4 (2013): 310–18. http://dx.doi.org/10.1590/s2317-17822013000400003.
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PURPOSE: To analyze the impact of body weight and body fat volume on selected parameters of vocal quality, phonatory range, and aerodynamics in females. METHODS: Based on measurements of body mass index in combination with body fat volume, 29 normophonic female subjects were classified as normal weight, underweight, and obese. Voice quality was investigated via auditory-perceptual ratings of breathiness, roughness, and overall dysphonia severity, via various acoustic measures and a multiparametric index. Phonatory range performance was examined using selected measures of the voice range profile and speech range profile. Measures of vocally relevant aerodynamics included vital capacity (i.e., VC), expected VC, phonation quotient, and maximum phonation time (i.e., MPT). RESULTS: Significant differences between the three weight groups were found across several measures of intensity, VC, MPT, and shimmer. As compared to the other groups, significantly higher values of maximum and minimum intensity levels, as well as sound pressure level during habitual running speech were observed for the obese group (all p-values<0.05); whereas, the underweight group had significantly lower values for VC and ratio of expected to measured VC (p-values<0.01). Furthermore, underweight subjects differed significantly as compared to normal weight subjects with lower MPT (p=0.025) and higher lowest-F0 (p=0.035). Finally the obese group showed significantly lower shimmer values than the normal weight subjects (p<0.05). CONCLUSION: Body weight and body fat volume appear to influence select objective measures of voice quality, vocal aerodynamics, and phonatory range performance.
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Rice, James. "Combined Environments Facility for Externally Carried Aircraft Stores." Journal of the IEST 34, no. 5 (September 1, 1991): 29–33. http://dx.doi.org/10.17764/jiet.2.34.5.053154t515148264.
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Raytheon Company, Electromagnetic Systems Division (ESD), Goleta, California, has recently completed a facility that simulates the environments measured on the AN/ALQ-184 EW Jammer Pod during a series of flight tests. The laboratory uses high-intensity acoustic excitation to duplicate the effects of turbulent aerodynamic flow, vibration exciters to drive the lower frequency air frame structural motions, temperature-conditioned air across the store to simulate the effects of frictional skin heating or frigid conditions, and temperature-conditioned coldplate fluid to create the correct thermal effect on the high voltage section of the pod (see Figure 1). This approach to testing externally carried stores builds on the work that has been done by the Navy at the Pacific Missile Test Center (PMTC), Point Mugu, California. The primary differences are in the use of two distinct thermal profiles applied simultaneously to different portions of the test item, and the use of multiple accelerometers in the control of the vibroacoustic environment. Special considerations had to be taken into account in the design of the test facility. Overall sound pressure levels of 155 dB were required to achieve the desired pod response. Space restrictions caused the facility to be placed within 21.3 m (70 ft) of the property boundary in an area zoned as a research park. Water restrictions in Santa Barbara County prevented the use of a water cooling system for equipment typically cooled by liquid. Both problems were addressed and successfully overcome. The completed lab is now being used for reliability growth testing and for lot sampling of the production pods.
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Gilbert, Kenneth E., Carrick L. Talmadge, and Xiao Di. "Measuring immeasurable sound pressure levels." Journal of the Acoustical Society of America 113, no. 4 (April 2003): 2247. http://dx.doi.org/10.1121/1.4780399.
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Ding, Wei. "Influence of Road Traffic Noise on English Reading Comprehension of Chinese College Students Majoring in English." International Journal of Emerging Technologies in Learning (iJET) 15, no. 14 (July 31, 2020): 109. http://dx.doi.org/10.3991/ijet.v15i14.15355.
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Noise has a negative impact on language learning. But first and second lan-guages are affected differently by noise. To clarify the effects of road traffic noise on second language learning, this study explores deep into how road traffic noise, the main noise on university campuses, affects the English reading comprehension of Chinese college students majoring in English. The subjects were asked to finish English reading comprehension tests of three difficulty levels (easy, medium and hard) under road traffic noises of three sound pressure levels (SPLs), namely, 30 dBA, 50 dBA and 70 dBA. The score, time consumption and number of interruptions of each subject were recorded, and subjected to one-way analysis of variance (one-way ANOVA). In addition, the subjects were asked to evaluate the impacts of road traffic noises on their comprehension. The results show that: the scores of English reading comprehension gradually decreased with the growing of the SPL of road traffic noise, but the decrease is only significant for easy questions; the time consumption of reading comprehension was not greatly affected by the SPL of road traffic noise; the subjects were interrupted more frequently by road traffic noises of 50 dBA and 70 dBA than road traffic noise of 30 dBA, but the difference is only significant for hard test; according to the self-evaluation of the English majors, interruption is the main problem brought by road traffic noise, which is replaced by distraction at the SPL of 70 dBA. Overall, the road traffic noise can disturb the English reading comprehension of Chinese college students majoring in English, and the disturbance is relat-ed to the difficulty of the text. The higher the SPL of the road traffic noise, the readers are more anxious and more frequently disturbed in reading, and the lower the score of English comprehension. In addition, attention should be paid to the disturbance of 30 dBA road traffic noise on second language learners.