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1
Adams, Christian, Regine Stutz, Elisabeth Kaiser, Michelle Bous, Sybelle Goedicke-Firtz, Franziska Hornberger, and Michael Zemlin. "Noise control engineering on neonatal incubators." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 3 (August 1, 2021): 3217. http://dx.doi.org/10.3397/in-2021-2338.
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Neonatal incubators provide suitable environmental conditions for premature newborns and allow for medical treatment such as medication and monitoring of vital functions such as blood pressure. The incubator includes several system components such as a control system, an oxygen supply, a scale or flaps and drawers for patient care and storage of medical material, respectively. These system components generate noise such as monitoring alarms, noise of the oxygen supply, or noise due to opening and closing of flaps during medical treatments. The noise leads to a significantly increased sound exposure inside the incubator. Increased sound exposure is known to cause distress and to increase the risk of acute or chronic diseases in the preterm neonate. This paper presents acoustic measurements on an incubator in a neonatal intensive care unit. Several vibration and acoustic measurements are performed inside the incubator as well as in the surrounding environment in order to characterize typical acoustic scenes from everyday life on the neonatal intensive care unit. Based on the measurement results, the scenes are categorized in terms of sound exposure. This forms the basis for a future design for acoustics of the incubator.
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Mao, Dingtao, and Yong Ding. "Measurement and analysis of bridge expansion joint noise." E3S Web of Conferences 293 (2021): 02053. http://dx.doi.org/10.1051/e3sconf/202129302053.
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The structure-borne noise while the vehicle passing across the bridge expansion joint is the main source of urban bridge noise. In order to control this noise pollution, 20 bridges including three types of typical expansion joints in Ningbo City were selected, and the noises were measured while vehicle passed across the bridge expansion joints. The measured results are expressed by the Z-weighted sound pressure level, which kept the effect of the low-frequency noise. Then the influence factors of this noise are discussed. The results show that: (1) The sound pressure while vehicle on the bridge expansion joints is much greater than that on the normal road or mid-span of the bridges, which results in significant environmental noise pollution; (2) The wider the gap of the bridge expansion joints, the greater the noise level; (3) The noises produced by the modular expansion joints and comb-plate expansion joints are greater than that from the single-gap expansion joints.
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Kong, Qing Fu, Yu Liang Dai, Shi Jian Zhu, and Jia Ming Wu. "Experimental Study on an Active Noise Control System for Turboprop Driven Aircraft." Applied Mechanics and Materials 333-335 (July 2013): 2142–45. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.2142.
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In order to find a solution to the control of low frequency noise in the cabin of turboprop driven aircraft, an experimental active noise control (ANC) system is introduced in the paper, which consists of vibroacoustic field analogue subsystem, acoustic field measurement subsystem and acoustic barrier exciter subsystem. Effects of both different spaces between the primary sound source and secondary sound source of the ANC system and different frequency noises on noise-reduction result are investigated based on the experimental platform. Results of the experiment show a significant potential of the ANC method for the control of low frequency noise in the cabin of turboprop driven aircraft.
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Nishikawa, Reon. "Passive control of the flow-induced noise from a rectangular cylinder using porous walls." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 2 (August 1, 2021): 4219–25. http://dx.doi.org/10.3397/in-2021-2635.
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A noise reducing technique for the flow-induced noise using a porous material was studied experimentally and numerically. In the experiment, flow-induced noises emitted from three types of rectangular cylinders were measured in a low-noise wind tunnel. One cylinder was made of four aluminum plates and others were made of two or three aluminum plates. Measurement results show that the frequency of the distinct tonal noise was different among three cylinders, that frequency was higher for using porous material. It was also found that the sound pressure lelvel of the noise was also different and that of the cylinder using two porous material plates was 25 dB smaller at maximum. Velocity field of the wake of cylinders were examined by the PIV measurement and that showed that time and space scale of separated vortices around cylinder were smaller for using two porous material plates. It is assumed that the change of aerodynamic sound was caused by that change in velocity field. In the numerical simulation, we could simulate changes of the emitted noise and the wake of the cylinder by applying the slip boundary condition of the velocity to the wall of the cylinder.
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Li, Zhong Xin, Guang Ping Wang, Shen Xu Wang, and Hong Jiang. "Vehicle Interior Noise Measurement and Analysis." Key Engineering Materials 467-469 (February 2011): 1072–77. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.1072.
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A method of vehicle interior noise order analysis was presented to resolve the loud noise problem in a new indigenous vehicle. Sound and vibration properties of the vehicle were tested. The interior noise and vibration acceleration signals at different positions were obtained, and the major sources of noise and vibration were identified. Base on these results, modifications were proposed for different noise sources. The results provide a reference for the optimal design of vehicle motor and transmission system and the internal noise control.
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Zaman, Taylan, Abdusselam Celebi, Bengusu Mirasoglu, and Akin Savas Toklu. "The evaluation of in-chamber sound levels during hyperbaric oxygen applications: Results of 41 centres." Diving and Hyperbaric Medicine Journal 50, no. 3 (September 30, 2020): 244–49. http://dx.doi.org/10.28920/dhm50.3.244-249.
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Introduction: Noise has physical and psychological effects on humans. Recommended exposure limits are exceeded in many hospital settings; however, information about sound levels in hyperbaric oxygen treatment chambers is lacking. This study measured in-chamber sound levels during treatments in Turkish hyperbaric centres. Methods: Sound levels were measured using a sound level meter (decibel meter). All chambers were multiplace with similar dimensions and shapes. Eight measurements were performed in each of 41 chambers; three during compression, three during decompression, and two at treatment pressure, one during chamber ventilation (flushing) and one without ventilation. At each measurement a sound sample was collected for 25 seconds and A-weighted equivalent (LAeq) and C-weighted peak (LCpeak) levels were obtained. Recorded values were evaluated in relation to sound level limits in regulations. Results: The highest sound level measured in the study was 100.4 dB(A) at treatment pressure while ventilation was underway and the lowest was 40.5 dB(A) at treatment pressure without ventilation. Most centres had sound levels between 70 dB and 85 dB throughout the treatment. Ventilation caused significant augmentation of noise. Conclusions: The chambers were generally safe in terms of noise exposure. Nevertheless, hyperbaric chambers can be very noisy environments so could pose a risk for noise-related health problems. Therefore, they should be equipped with appropriate noise control systems. Silencers are effective in reducing noise in chambers. Thus far, hyperbaric noise research has focused on chambers used for commercial diving. To our knowledge, this is the first study to investigate noise in hospital-based chambers during medical treatments.
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Liu, Bin, Tao Feng, Xue Wu, and Nan Li. "Noise Radiation Characteristics of the Washing Machine Based on Sound Intensity Measurement." Advanced Materials Research 482-484 (February 2012): 1406–9. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.1406.
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Based on the sound intensity measurement and analyzing, the noise radiated from the washing machine with horizontal axis was discussed to identify the noise source and find its propagation path. According to the principle of the sound intensity measurement, the measurement grids were arranged at the outside surfaces of the washer, and the distance was set to 20cm. The result showed that the noise source was near the right surface of washer’s motor installing. The maximum sound intensity values are mainly in frequency bands of 2 KHz and 4 KHz. Back surface of washer with sound power level 51 dB radiated the maximum sound intensity value 55.8 dB for 2 KHz and 56.0 dB for 4 KHz. There was also appeared the maximum sound intensity of low frequency 100 Hz in Right surface, which was caused by the vibration of motor transferring to the right surface shell. The results can provide technology support for the noise control of washing machine.
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Nakayama, Shohei, Kenji Muto, Kazuo Yagi, and Guoyue Chen. "Sound source measurement of magnetic resonance imaging driving sound for feedforward active noise control system." Journal of the Acoustical Society of America 133, no. 5 (May 2013): 3302. http://dx.doi.org/10.1121/1.4805467.
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Wang, X., and A. Subic. "Psychoacoustic modelling of vehicle side mirror power-fold actuator noise characteristics." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 6 (April 13, 2011): 1419–29. http://dx.doi.org/10.1177/0954406211399514.
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A study of vehicle side mirror power-fold actuator noise characteristic was undertaken, which seeks to correlate subjective evaluation with objective measurements as a basis for development of a product sound quality control algorithm. Psychoacoustic metrics were extracted from the product sound measurements and analysed for manufacturing quality assessment. Two approaches were explored in this study; one is a multiple metric sequential pass-through gate approach and the other is the least square fit regression approach, where measured relevant psychoacoustic metrics are modelled against subjective rating data provided by product sound quality evaluation experts. The ‘gate’ approach using sound pressure level, roughness, and tonality was successfully implemented to segregate bad power-fold actuators from good ones in terms of sound quality. A non-linear, two metric regression algorithm assessing what is a ‘good’ or a ‘bad’ actuator, was then developed and validated through comparison with a linear eight metric regression algorithm. Based on correlation of objective measurement and subjective evaluation results for given product samples, the diagnostic methodology developed in this research is applicable to other products for noise diagnostics and quality control.
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ISAKA, Hideharu, and Yuichi HASHIMOTO. "Research on Active Control System for Toilet Noise by Sound Visualization Measurement." Proceedings of the Dynamics & Design Conference 2019 (2019): 314. http://dx.doi.org/10.1299/jsmedmc.2019.314.
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Ümmühatun Özen, Zeynep, Mustafa Tosun, and Enes Yasa. "Investigation of the Effect of Traffic Noise in Inspection of Urban-Level Noise: A Noise Analysis in Konya - Nalcaci Street." Athens Journal of Τechnology & Engineering 8, no. 1 (January 20, 2021): 91–112. http://dx.doi.org/10.30958/ajte.8-1-4.
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In this study, the effects of noise, due to the increase in population in urban centers, industrialization and land traffic, are evaluated on human health, indoor life standards, and auditory comfort. For this purpose, noise levels were recorded in Ahmet Hilmi Nalcaci Street, which is one of the densest streets of Konya. The recordings were performed at 14 different stations, three times a day and for 14 days. A "Testo 815" brand device was used for measurement and recording. The results of the measurements were evaluated according to international standards and domestic regulations, taking into account the situations where windows and doors, which constitute integrity and blanks in the envelope of a structure, are open. It was determined that the noise levels recorded at the stations are above the discomfort threshold. Settlement-and architecture-level measures to reduce and control noise are suggested in the study. It was determined that the most effective measure in this context would be isolation in structure envelopes. Types of walls generally used in the buildings around the street, which is the subject of the study, were determined and the sound penetration loss values for these walls were given. The sound penetration loss values were also compared to indoor noise limit values in certain measurement points and excessive noise values were presented in the study. Keywords: Noise pollution, traffic noise control, environmental noise, urban level noise, Testo 815
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Mężyk, Jordan, Artur Flach, and Andrzej Zbrowski. "Control System of a Manipulation Mechanism for Acoustical Measurement in Anechoic Chamber." Solid State Phenomena 198 (March 2013): 467–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.198.467.
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The article considers the previously presented manipulating mechanism for positioning of a microphone during acoustical measurements in anechoic chamber. Usually the aims of acoustical measurements in anechoic chamber are: estimation of Sound Power Level of the noise source, measurement of directional characteristics of an electroacoustical transducer, measurement of the sound diffusion characteristic of a given structure and a measurement of Sound Pressure Level on a given measurement grid. The specific of that kind of measurements brings up the need of measurement microphone positioning in many points of the measurement space accordingly to relevant standards. In most cases during the tests it is necessary to position the microphone in certain points on the hemisphere. In such cases utilizing of typical microphone stands impedes the measurement and extends the time needed for the tests. The presented manipulation system for a measurement microphone allows positioning the microphone on the hemisphere around the tested object as required by the standards on the Sound Power Level measurement. Its construction is a simple, rigid form aiming at little effect on the acoustic field inside the chamber whereas the control system and the software are targeted at the maximal flexibility that allows not only standard testing but also scientific research in freely selected scenarios. Since its initial introduction the system has been extended by an additional axis that is used for rotating the microphone, which allows its positioning on the line that is coincident with the centre of rotation of the turntable. Such an extension eliminates the problem of use of the corrections of the directional characteristics of the microphone when measuring the sound signal. The microphone can be positioned directly towards the source of the sound. The article briefly reviews the mechanical construction of the positioning mechanism and focuses on the structure of the control section of the drive system constructed in the manipulator. The method for cooperation of actuators and the control system is presented. Also the description is given for the internal structure of the multi-level control circuits built in the applied drives. Finally the structure of the control application is presented.
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Choi, Hyeung Sik, Hee Young Shin, Ji Youn Oh, Tae Woo Lim, and Yun Hae Kim. "Temperature Regulation for LED Lamps Using Fans." Advanced Materials Research 753-755 (August 2013): 1931–38. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.1931.
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A temperature regulation control for LED(Light Emitting Diode) lamp using a cooling fan was studied. An efficient temperature regulation scheme using fan wind at the lowest sound noise was studied. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan with various size of heat sinks was performed. Also, characteristics and relationship of heat sinks and fans are studied through experiments. To reduce the fan sound noise, a method of reducing the operation time with optimal size of the heat sink was studied.
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Olsman, W. F. J., and B. I. Schuchardt. "Segmentwise Measurement of Helicopter Approach Noise with a Reduced Microphone Setup." Journal of the American Helicopter Society 60, no. 4 (October 1, 2015): 1–18. http://dx.doi.org/10.4050/jahs.60.042005.
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To measure the noise footprint of a helicopter approach procedure, microphones are usually distributed over a large area. In this paper, however, a method is utilized where the measurement of the noise footprint is conducted in parts by distributing the microphones over a limited area and executing the same approach procedure, while the position of the landing point is shifted. The flight tests are conducted with the EC135-ACT/FHS helicopter. Guidance to the pilots is provided by use of a “tunnel-in-the-sky” head down pilot display. Since the same flight procedure is executed multiple times, it is possible to conduct a statistical analysis on the accuracy and reproducibility of the approach procedure in terms of position, velocity, and generated noise. This statistical analysis shows that the geometric accuracy is on the order of 6 m in the horizontal plane and 12 m in the vertical plane. The variations in the measured sound exposure level from one approach to another are on the order of 3–7.5 dB(A). The approach procedure is also executed with excessive cyclic pilot control inputs to identify an upper limit of the extra noise generated by unsteady flight. However, these approaches are indistinguishable, in terms of the sound exposure level or sound pressure level, from the approaches with normal pilot control inputs.
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Min, Liang, W. U. Dasheng, and Zhang Xiying. "A Simplified Method for Field Measurement of Airborne Sound and Impact Sound Insulation in Buildings." Building Acoustics 1, no. 2 (June 1994): 137–49. http://dx.doi.org/10.1177/1351010x9400100204.
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A simplified method is investigated to be developed for use by building control inspectors or persons undertaking a similar role to allow a fast and simple check to be carried out on both air-borne and impact sound insulation between rooms. This paper proposes a short test method, in which a standard impact noise source is employed as a simplified source and one third octave band sound level measurement is simplified by A-weighting.
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Lin, Chi-Chwen, Yen-Ping Peng, Yung-Pin Tsai, Yu-Chen Chang, and Ku-Fan Chen. "Impact and Control of Reflected Noise from an Overpass Bottom." Applied Sciences 8, no. 10 (October 14, 2018): 1908. http://dx.doi.org/10.3390/app8101908.
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This study examines the effects of noise reflected from the overpass bottom under various conditions using onsite measurements and model simulation. Reflected noise from the overpass bottom may be as high as 8 dB(A). Bottom materials (steel and reinforced concrete (RC)) have no discernible effect on the reflected noise level. As the height of an overpass increases, the level of reflected noise decreases. When an overpass is parallel to the noise source (i.e., the freeway), the size of the area impacted by reflected noise increases. As the sound absorption rating of the material installed at the overpass bottom increased, the level of reflected noise decreased. A sound absorbing material with a sound absorption rate of at least 0.60 is recommended to reduce reflected noise level. When the distance between the overpass side and a receiver exceeded 30 m, the level of reflected noise level reduced significantly. Therefore, if the distance between a residential area and overpass could be increased to create a buffer zone coupled with the installation of sound absorbing material at the overpass bottom, the impact of reflected noise on nearby residents can be reduced.
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Bukhtiyarov, Igor V., Nicolay N. Courierov, Alla V. Lagutina, Lyudmila V. Prokopenko, and Evgeny V. Zibarev. "Aircraft noise in residential areas, problems of measuring and evaluation." Hygiene and sanitation 99, no. 10 (November 30, 2020): 1042–48. http://dx.doi.org/10.47470/0016-9900-2020-99-10-1042-1048.
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The intensity of civil aircraft flights elevates with the increase in the number of passenger and cargo transportation by air. Aircraft noise in the residential area near airports grows up too despite the use of low-noise aircraft models by airlines. This causes an augmentation in the number of complaints of the population in these areas. The Russian Federation’s normative and methodological documents requirements in force relating to measurements and assessment of noise in residential areas, including «aircraft noise», were analyzed. Their requirements in terms of measuring and assessing noise in residential areas, including “aircraft noise”, testifies to the insufficiency and ambiguity of these requirements. The main disadvantages are the lack of a clear definition of which sound event is considered «aircraft noise» and the lack of requirements for the duration of the reference time interval of noise measurement. The foreign experience of measuring and evaluating aircraft noise, as well as the effects of such noise on the population, are considered. This made it possible to determine the necessary and sufficient parameters for noise control in residential areas, including «aircraft noise». There were proposed both a definition of «aircraft noise» and the necessary parameters for its assessment. The necessary duration of the reference time interval for the measurement of normalized parameters was justified. Method for the normalized noise parameters in residential areas measurement using the chronograms of sound levels A was proposed. The technical implementation of such a method is presented. Proposed a definition of «aircraft noise» and measuring normalized parameters in the 15-minute reference time interval for inclusion in regulatory and methodological documents will help to eliminate ambiguity in measurements and noise assessment in residential areas.
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Riadiany, Pradita Wira, and Sugeng Abdullah. "STUDI TENTANG INTENSITAS SUARA DANUPAYA PENGENDALIAN KEBISINGAN DI BANDAR UDARAHUSEIN SASTRANEGARA BANDUNG TAHUN 2014." Buletin Keslingmas 34, no. 1 (March 31, 2015): 36–53. http://dx.doi.org/10.31983/keslingmas.v34i1.3022.
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PDAM Tirtawening Environmental Quality Control Measurement Laboratory Bandung stated thatHusein Sastranegara airport had highest noise intensity equal to 89.83 dB (A) so that the researcherwants to investigate the sound intensity and noise control in the Husein Sastranegara airport Bandung2014.The research design used was descriptive research which was intended to obtain vivid descriptionrelated sound intensity and noise control in Husein Sastranegara airport Bandung 2014 with five-pointmeasurement that describes the apron (aircraft parking space), check in / luggage space and the ticketprocess, passengers waiting room, public park, and housing.The research results shows that the sound intensity in Husein Sastranegara airport Bandungmeasurement in all locations for 83.78 dB (A) on the apron (aircraft parking area), 72.66 dB (A) at thecheck in / hall ticket and luggage process, 75.37 dB (A) in the passenger waiting room, 65.93 dB (A) atthe public parking lot and 68.52 dB (A) at the housing. The highest sound intensity results was in theapron (aircraft parking area) 85.33 dB (A) at 08:40 am.Manager of Husein Sastranegara airport Bandung expected to encourage the airports employeesto use personal protective equipment such as ear muff while on duty at the apron (aircraft parking) andconduct sound intensity measurement on a regular basis in order to recognize hazard that can interferewith employee activities.
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Bernhard, Robert J., and Rebecca S. McDaniel. "Basics of Noise Generation for Pavement Engineers." Transportation Research Record: Journal of the Transportation Research Board 1941, no. 1 (January 2005): 161–66. http://dx.doi.org/10.1177/0361198105194100121.
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This paper is intended as a brief basic primer on tire–pavement noise generation and measurement. It is particularly directed toward pavement and materials engineers who are aware that noise is an issue of concern to the public but have not been able to invest the time needed to investigate and learn about noise control fundamentals. This paper defines sound and noise, illustrates the public's growing awareness of noise issues, explains the units of measurement and measurement techniques, outlines some of the mechanisms of noise generation at the tire–pavement interface, and briefly discusses how pavements can help to mitigate noise problems. Significant progress has been made to reduce tire–pavement noise, and, with more applications and an increased understanding of noise generation and propagation, economical pavements are possible that control noise while maintaining safety and durability.
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Zhang, Li, Shuo Zhang, and Yan Miao Ma. "Sound Intensity Test Analysis of the Acoustic Enclosure for the Refrigeration Compressor." Applied Mechanics and Materials 312 (February 2013): 296–300. http://dx.doi.org/10.4028/www.scientific.net/amm.312.296.
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According to the international standard ISO 9614-1:1993 " Determination of sound power levels of noise sources by the sound intensity method - Part1: Measurement at discrete points, the sound intensity test was conducted on the acoustic enclosure for the refrigeration compressor with the PULSE software. The sound insulation performance of the acoustic enclosure was analyzed by comparing the compressors noise with and without the enclosure. The result shows that the noise of the compressor with the acoustic enclosure is less than 60dB (A), and the high-frequency noise can be greatly reduced, which meets the design requirements of noise control. Therefore, it is easy to conclude that the sound insulation of the acoustic enclosure reaches the design standards and the acoustic enclosure design is feasible. The paper provides a valuable reference for the further study on the designing and optimizing of the acoustic enclosure.
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Evans, Jack B. "Structural Floor Vibration and Sound Isolation Design for a Magnetic Resonance Imaging System." Building Acoustics 12, no. 3 (September 2005): 207–23. http://dx.doi.org/10.1260/135101005774353050.
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This is a case study about noise and vibration control problems, and the design constraints and solutions for a proposed installation of a magnetic resonance imaging system (MRI) in an existing medical research facility. Manufacturer's data indicated that airborne sound level emissions over a broad frequency span could exceed permissible noise criteria for nearby occupied rooms. The building structure also required reinforcement to accommodate the MRI magnet's concentrated load, but invasive disturbance to a transgenic research mouse vivarium on the floor below was prohibited. The structure borne vibration paths needed attenuation or isolation. Design parameters included structural strength, stiffness and the specific platform resonant frequency (non-coincident with known vibration sources or building structure). In addition, acoustical containment was required for anticipated noises from the magnet room, to prevent excessive or annoying and distracting noise in the MRI control room or other adjacent (but unrelated) research, animal holding and office spaces. Structural “de-tuning” and architectural “decoupling” concepts were employed. A resonant frequency criterion was recommended for the new structural floor design. A combination of vibration spectrum analysis, dynamic analyses of alternate structural concepts and existing physical conflict constraints led to the design of an independent platform floor above the existing building floor. Post construction floor vibration measurements were compared to earlier measurement data to show quantitative change in performance. The modifications satisfied acoustical criteria and occupants' subjective evaluations.
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Bonnett, Jonathan, Carmel Cuschieri, and Joseph M. Cuschieri. "Noise Control design for a Ventilation Fan - Case Study." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 1 (August 1, 2021): 5731–39. http://dx.doi.org/10.3397/in-2021-3238.
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A ventilation system was design and installed for a multi story garage. The ventilation system system had a vertical concrete shaft with the ventilation fan located on the top floor at street level. The ventilation fan is separated from the outside by a set of metal louvers. Adjacent to the louvers is an open pedestrian area. The exhaust fan as installed had an inline duct silencer but this was insufficient in terms of providing the desired noise mitigation. The project desire was not to make changes to the fan or its inline silencer or the external louvers so an alternative noise mitigation option had to be explored. Based on the provided sound power characteristics of the fan, the exterior noise levels as calculated matched the expected levels coming out of the metal louvers. The interior of the ventilation shaft is bare concrete with the fan installed though a hole in the concrete top floor. The predominate noise was the very high reverberation inside the ventilation shaft. The owner of the property made an attempt at installing noise absorption but this was not sufficient. Based on the field data the sound levels with the preliminary absorption solution matched expectation, but further noise reduction was required. A complete sound absorption on the walls of the concrete ventilation shaft noise mitigation solution was design, and the expected levels predicted to show that significant noise reductions can be obtained by a comprehensive noise absorption solution. The noise mitigation solution was implemented and exterior sound level measurements performed at the completion of the project. The measured sound levels outside of the metal louvers were in very good agreement with the predicted levels. Based on the success of this first noise mitigation solution, noise mitigation for a second ventilation system is not being considered.
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Koopmann, G. H., W. Neise, and W. Chen. "Active Noise Control to Reduce the Blade Tone Noise of Centrifugal Fans." Journal of Vibration and Acoustics 110, no. 3 (July 1, 1988): 377–83. http://dx.doi.org/10.1115/1.3269529.
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This paper describes an active noise control method to suppress the blade tones of centrifugal fans. Two secondary sound sources are mounted into the cutoff region of the fan casing. These sources are driven with electrical signals that are synchronized with the rotation of the impeller, and their amplitudes and phase are adjusted to give maximum reduction for the blade tone levels in the inlet and outlet duct of the fan. With this design, the sound emitted by the secondary sources is introduced into the interior of the casing near the source region where the blade tone is generated, i.e., the cutoff. The present experiments were concentrated on the reduction of the fundamental of the blade tone for centrifugal fan with impeller diameters between 280 mm (11 in.) and 710 mm (28 in.). Two different designs of secondary sources were investigated. In the first, two loudspeakers are contained within an enclosure which has an open end made of a curved perforated plate which replaces part of the original cutoff. The second design incorporates two vibrating plates which replace portions of the outlet duct side and the volute side of the cutoff. Reductions in tone sound pressure level of up to 23 dB have been observed for a variety of aerodynamic loading conditions and fan inlet geometries. To obtain a better understanding of the physical mechanism of this active noise control method, sound pressure measurements were also made on the inner surface of the fan casing along the volute. Both amplitude and phase of the blade passing frequency component were measured relative to a reference signal derived from the impeller rotation. The result of this experiment is that the sound field inside the casing is dominated by the pressure pattern rotating together with the impeller. Since the impeller tip Mach number is well below sonic speed, however, the radiation efficiency of the rotating pressures is very low. The blade tone noise measured in the far-field is generated by the unsteady pressures at the cutoff which in turn are produced by the flow leaving the impeller. This aerodynamic noise generating mechanism is modified by the active sources located in the cutoff.
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Chen, Fu Zhong, Yong Jun Shi, and Lei Yan Yu. "Gear Meshing Noise of the Closed Gearbox." Applied Mechanics and Materials 607 (July 2014): 527–30. http://dx.doi.org/10.4028/www.scientific.net/amm.607.527.
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The dynamic excitation and the noise of meshing gears were analyzed quantitatively using the three-dimensional finite element contact analysis and the boundary element method. The distribution and variation roles of the gear mesh noise were obtained. The simulation result was verified by sound power measurement. The main excitation was determined additionally. It provides the theory basis for the control of the gearbox noise.
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Chai, Shiyi, Xiaoqin Liu, Xing Wu, and Yanjiao Xiong. "Separation of the Sound Power Spectrum of Multiple Sources by Three-Dimensional Sound Intensity Decomposition." Sensors 21, no. 1 (January 4, 2021): 279. http://dx.doi.org/10.3390/s21010279.
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The identification and separation of sources are the prerequisite of industrial noise control. Industrial machinery usually contains multiple noise sources sharing same-frequency components. There are usually multiple noise sources in mechanical equipment, and there are few effective methods available to separate the spectrum intensity of each sound source. This study tries to solve the problem by the radiation relationship between three-dimensional sound intensity vectors and the power of the sources. When the positions of the probe and the sound source are determined, the sound power of the sound source at each frequency can be solved by the particle swarm optimization algorithm. The solution results at each frequency are combined to obtain the sound power spectrum of each sound source. The proposed method is first verified by a simulation on two point sources. The experiment is carried out on a fault simulation test bed in an ordinary laboratory; we used three three-dimensional sound intensity probes to form a line array and conducted spectrum separation of the nine main noise sources. The sound intensity on the main frequency band of each sound source was close to the result of the near-field measurement of the one-dimensional sound intensity probe. The proposed spectral separation method of the sound power of multiple sound sources provides a new method for accurate noise identification in industrial environments.
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Kaczmarska, Anna, and Danuta Augustyriska. "Study of Sound Insulation of Control Cabins in Industry in the Low Frequency Range." Journal of Low Frequency Noise, Vibration and Active Control 11, no. 2 (June 1992): 42–46. http://dx.doi.org/10.1177/026309239201100202.
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The number of control cabins installed in industry has increased considerably during the last few years. Most cabins installed nowadays show a satisfactory noise reduction in the frequency range above 500 Hz. The effect of noise damping however shows a gradual decrease for lower frequencies. The present paper is a description of the distribution of low frequency noise in different types of control cabins installed in typical low frequency noise environments in steel plants and the machine building industry. Measurements were made in 20 control cabins, constructed of metal and stone Measurements of sound pressure levels in octave bands were made inside and outside the cabins. The sound pressure level in octave bands in the low frequency range (4–31.5 Hz) inside the cabins was high and varied between 60–108 dB. This is probably due to the insufficient noise reduction for lower frequencies. In some control cabins there was an increased level of low frequency noise inside the cabin compared to the outside. In these control cabins sound pressure levels exceed the admissible values according to Polish standards. The increase of noise level within the low frequency range is considered to be based on resonances.
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Sh., Shabani, and Zarei Sh. "Evaluating of Noise Pollution in the Airside of Imam Khomeini International Airport." Modern Applied Science 11, no. 6 (April 23, 2017): 47. http://dx.doi.org/10.5539/mas.v11n6p47.
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Detection, measurement and monitoring of environmental pollution are considered as one of the decision basics in the environmental management. Principle planning for solving environmental problems is not possible without reliance to assured measurement with the help of new and powerful systems in monitoring. In this regard the noise pollution of airports is of great importance. In this paper by using device analysis method and utilizing a calibrated sound level meter device, sources of noise pollution recognition, noise and sound pressure level measurement, evaluation and comparison of them with environmental standards, and airside control actions of the Imam Khomeini international airport have been performed and it was showed, that the runway, ground safety and the dock have been respectively the main pollutants, so that noise pollution in the Apron area and runway at night have been 80.7% more than Iran standards and the ground safety site while alarm broadcasting has been 53.1% at daytime and 61.1% at night more than standards and these values for Dock has been 20.88% and also the value of noise pollutants in water refinery sites, watchtower, taxi parking and pilgrim terminals have met standards. Finally some solutions against noise pollution have been proposed.
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Lv, Na, Jiyong Zhong, Jifeng Wang, and Shanben Chen. "Automatic measuring and processing system of audio sensing for real-time arc height control of pulsed GTAW." Sensor Review 34, no. 1 (January 14, 2014): 51–66. http://dx.doi.org/10.1108/sr-02-2013-628.
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Purpose – Surface forming control of welding bead is the fundamental study in automated welding. Considering that the vision sensing system cannot extract the height information of weld pool in pulsed GTAW process, so this paper designed a set of automatic measurement and control technology to achieve real-time arc height control via audio sensing system. The paper aims to discuss these issues. Design/methodology/approach – The experiment system is based on GTAW welding with acoustic sensor and signal conditioner. A combination denoising method was used to reduce the environmental noise and pulse interference noise. After extracting features of acoustic signal, the relationship between arc height and arc sound pressure was established by linear fitting. Then in order to improve the prediction accuracy of that model, the piecewise linear fitting method was proposed. Finally, arc height linear model of arc sound signal and arc height is divided into two parts and built in two different arc height conditions, which are arc height 3-4 and 4-5-6 mm. Findings – The combination denoising method was proved to have great effect on reducing the environmental noise and pulse interference noise. The experimental results showed that the prediction accuracy of linear model was not stable in different arc height changing state, like 3-4 and 4-5-6 mm. The maximum error was 0.635588 mm. And the average error of linear model was about 0.580487 mm, and the arc sound signal was accurately enough to meet the requirement for real-time control of arc height in pulse GTAW. Originality/value – This paper tries to make a foundation work to achieve controlling of depth of welding pool through arc sound signal, then the welding quality control. So a new idea of arc height control based on automatic measuring and processing system through arc sound signal was proposed. A new way to remove environmental noise and pulse interference noise was proposed. The results of this thesis had proved that arc sound signal was an effective features and precisely enough for online arc height monitoring during pulsed GTAW.
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Grynkiewicz-Bylina, Beata, and Bożena Rakwic. "Measurements and Assessment of Sound Emitted by Toys Intended for Children under the Age of Three Years Old." Archives of Acoustics 40, no. 3 (September 1, 2015): 383–93. http://dx.doi.org/10.1515/aoa-2015-0040.
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AbstractToys emitting sounds are classified as significant sources of noise found in the children environment. Impulse and continuous noise emitted by toys, used in close to the child’s ear, acting directly on the organ of hearing, can lead to serious adverse health effects. This is especially true for children under the age of three, in which the state of the hearing organ determines their intellectual development.The current level of safety of sound emitting toys intended for children in this age group is insufficient. This is confirmed by the reports from the control of market surveillance authorities.A new approach to the assessment of children’s exposure to noise generated by toys, included in EN 71-1:2011 + A2:2013 Standard, based on the permissible values applicable to the workplaces, requires further tests and verification.The paper presents the results of the research work and assesses the level of sound emitted by toys in the light of current standard requirements, carried out using the author’s methodology. Toys intended for children under the age of 3 years, commercialized on the European market by Polish manufacturers and importers were tested. The results of the tests allowed us to determine the impact of duration of the sound pressure level measurement on the final result.
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Xie, Zhi Yong, Qi Dou Zhou, and Deng Yuan Mo. "Experimental Investigation of Ribbed Cylinder's Vibroacoustics Transmissibility." Advanced Materials Research 516-517 (May 2012): 714–17. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.714.
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Exciting force's accurate measurement is crucial to the structure-born sound radiation. And the force sensor is calibrated by the dynamic force calibration equipment. Exciting force is accurately measured on the ribbed cylinder’s forced vibration and sound radiation. Based on the steady sine and random white noise exciting, the frequency response functions of the acceleration and sound pressure are obtained. Results obtained from the two methods are shown to be in good agreement with each other. According to the acceleration’s frequency response functions and sound pressure’s frequency response functions, it is obvious that the peak frequencies in the two frequency response functions are corresponding to each other. And the correspondence relationship could be used to help control the radiated noise.
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Gryboś, Dominik, Jacek S. Leszczyński, Dorota Czopek, and Jerzy Wiciak. "Exhaust Noise Reduction by Application of Expanded Collecting System in Pneumatic Tools and Machines." Energies 14, no. 6 (March 13, 2021): 1592. http://dx.doi.org/10.3390/en14061592.
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In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead of a muffler, we propose the expanded collecting system, where the air expands through the pneumatic tube and expansion collector. We have elaborated a mathematical model which illustrates the dynamics of the air flow, as well as the acoustic pressure at the end of the tube. The computational results were compared with experimental data to check the air dynamics and sound pressure. Moreover, the study presents the methodology of noise measurement generated in a pneumatic screwdriver in a quiet back room and on a window-fitting stand in a production hall. In addition, we have performed noise measurements for the pneumatic screwdriver and the pneumatic screwdriver on an industrial scale. These measurements prove the noise reduction of the pneumatic tools when the expanded collecting system is used. When the expanded collecting system was applied to the screwdriver, the measured Sound Pressure Level (SPL) decreased from 87 to 80 dB(A).
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Steele, Daniel, and Catherine Guastavino. "Quieted City Sounds during the COVID-19 Pandemic in Montreal." International Journal of Environmental Research and Public Health 18, no. 11 (May 30, 2021): 5877. http://dx.doi.org/10.3390/ijerph18115877.
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This paper investigates the transformation of urban sound environments during the COVID-19 pandemic in Montreal, Canada. We report on comparisons of sound environments in three sites, before, during, and after the lockdown. The project is conducted in collaboration with the Montreal festival district (Quartier des Spectacles) as part of the Sounds in the City partnership. The analyses rely on continuous acoustic monitoring of three sites. The comparisons are presented in terms of (1) energetic acoustic indicators over different periods of time (Lden, Ld, Le, Ln), (2) statistical acoustic indicators (L10, L90), and (3) hourly, daily, and weekly profiles of sound levels throughout the day. Preliminary analyses reveal sound level reductions on the order of 6–7 dB(A) during lockdown, with differences more or less marked across sites and times of the day. After lockdown, sound levels gradually increased following an incremental relaxation of confinement. Within four weeks, sound levels measurements nearly reached the pre-COVID-19 levels despite a reduced number of pedestrian activities. Long-term measurements suggest a ‘new normal’ that is not quite as loud without festival activities, but that is also not characterizable as quiet. The study supports reframing debates about noise control and noise management of festival areas to also consider the sounds of such areas when festival sounds are not present.
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Kong, Yaguang, Xuyang Tao, and Zhangpin Chen. "Sound field measurement and evaluation research for radiated acoustic fields in amplitude-variable sonochemical systems." Measurement and Control 52, no. 9-10 (October 19, 2019): 1499–507. http://dx.doi.org/10.1177/0020294019877488.
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The content of this study is based on the background of sonochemistry processes. First, the hydrophone is used to measure the sound pressure in the reactor (the experimental ultrasonic frequency range is 20 ± 1 kHz). The sound pressure signals are processed by threshold method, Kalman filter algorithm, and five-point three-time smoothing method. These methods eliminate singular items in the sound pressure signal, filter noise, smooth burrs, and so on. In addition, the sound intensity value is calculated by dual hydrophone method. In this paper, the average intensity of ultrasonic cavitation is studied. The radial distribution and longitudinal distribution of cavitation intensity of the same tool head are studied, and the effects of different power and different tool heads on cavitation intensity are also discussed in this paper. The experimental results show that the instrument designed in this paper can effectively measure the distribution of ultrasonic sound field and evaluate the performance of the tool head. We can infer from the experiments that the performance of the diamond tool head is better than that of the nine-section whip and the dumbbell tool head.
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Samodra, FX Teddy Badai, Irvansyah, and Collinthia Erwindi. "An integrated control on thermal and noise environment of tropical building material." E3S Web of Conferences 67 (2018): 04012. http://dx.doi.org/10.1051/e3sconf/20186704012.
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The environmental problems of thermal and noise environment are recently considered the most important contributors to the tropical building in an urban area. The porous tropical materials provide both a solution for cooling and airborne noise problem from the source to receiver when the wind is in the same direction. This research optimizes the integrated control of thermal and noise environment which are directed into building material evaluation. Surabaya is selected as representative of the hotter area of the lowland while Malang is determined as the colder urban area of the highland. An eco-tropical lightweight material, wood, is examined as a case study. The field measurement for surface material temperature and its transmission loss were conducted in order to give information on thermal and acoustical properties of the material. The optimization is conducted by comparing Sound Reduction Index and by Conduction Heat Flow. The results highlighted that for the same material, the thickness that effect on its mass is important for both thermal and noise control. The higher the thickness is, the higher the Sound Reduction Index and the lower the conduction heat flow are. Modifying material by adding the thickness of wood results that by material mass minimum 36.5 kg/m2, the critical lowland building meets the standard of World Health Organization noise limits and has lower heat gain.
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Hu, Bing Yi, Hua Liang Teng, Xue Feng Zhang, Lu Bai, and Kai Fan Wu. "An IP Based Audio Test Network for Tunnel Application." Applied Mechanics and Materials 568-570 (June 2014): 441–47. http://dx.doi.org/10.4028/www.scientific.net/amm.568-570.441.
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An accurate measurement of noise wave is the key to effective noise control in a tunnel. In this paper, an IP based audio test network is presented. This network includes 100 battery powered recorders and a WIFI network. Each recorder can acquire 2 channels of audio waves and be triggered by external signals of infrared or electrical synchronic pulse. A main control computer connects these recorders to setup parameters and collect data via the WIFI network. Sensors are reassembled to be compatible with the interface of standard sound source. Meanwhile each sensor is fixed in a sensor holder, which can be placed to any position on a plane and can be used to adjust its sensor to 0-180 degrees in both of X-Y direction. The sound source generates various signals, such as clicks, tones, and tone bursts, to help understand how the sound propagates in tunnels. This designed network is capable of acquiring multipoint sound waves synchronously.
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Bérengier, Michel C., and Fabienne Anfosso-Lédée. "State-of-the-Art Prediction and Control of Road Traffic Noise in France." Transportation Research Record: Journal of the Transportation Research Board 1626, no. 1 (January 1998): 71–77. http://dx.doi.org/10.3141/1626-09.
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Because traffic noise is considered by the French population as the primary environmental nuisance, prediction of road traffic noise and development of efficient noise control techniques is very important. The first step is to analyze the source, the main part of which is due to the contact between tires and the road pavement. Many efforts have been devoted to the assessment of a reliable measurement method, and a classification of road pavements in relation to noise has been established for some years. To abate road traffic noise, special attention has been paid to low-noise pavements. Thus, the modeling of the absorption properties of porous asphalts has been particularly studied in the past 10 years. The second step is to understand the physics of sound propagation outdoors, especially the meteorological effects on the propagation of road traffic noise. Both theoretical and experimental approaches have been undertaken. Finally, the effect of road noise barriers of any shape on the propagation of road noise and their interaction with porous road surfaces have been investigated by using numerical models.
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Ku, J. M., W. B. Jeong, and C. Hong. "Active control of compressor noise in the machinery room of refrigerators." Noise Control Engineering Journal 67, no. 5 (September 1, 2019): 350–62. http://dx.doi.org/10.3397/1/376730.
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The low-frequency noise generated by the vibration of the compressor in the machinery room of refrigerators is considered as annoying sound. Active noise control is used to reduce this noise without any change in the design of the compressor in the machinery room. In configuring the control system, various signals are measured and analyzed to select the reference signal that best represents the compressor noise. As the space inside the machinery room is small, the size of a speaker is limited, and the magnitude of the controller transfer function is designed to be small at low frequencies, the controller uses FIR filter structure converged by the FxLMS algorithm using the pre-measured time signal. To manage the convergence speed for each frequency, the frequency-weighting function is applied to FxLMS algorithm. A series of measurements are performed to design the controller and to evaluate the control performance. After the control, the sound power transmitted by the refrigerator is reduced by 9 dB at the first dominant frequency (408 Hz in this case) and 3 dB at the second dominant frequency (459 Hz here), and the overall sound power decreases by 2.6 dB. Through this study, an active control system for the noise generated by refrigerator compressors is established.
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Hodgson, Murray. "Acoustical Evaluation of Six ‘Green’ Office Buildings." Journal of Green Building 3, no. 4 (November 1, 2008): 108–18. http://dx.doi.org/10.3992/jgb.3.4.108.
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To explain the reactions of the building occupants to their acoustical environments, meetings with the designers, walk-through surveys, and detailed acoustical measurements were done. The objective was to determine how design decisions affect office acoustical environments, and how to improve the acoustical design of ‘green’ office buildings. Design-performance criteria were established. Measurements were made of noise level, reverberation time, speech-intelligibility index (SII), and noise isolation. Noise levels were atypically low in unoccupied buildings with no mechanical ventilation, but excessive in areas near external walls next to noisy external noise sources—especially with windows open for ventilation—and in occupied buildings. Reverberation times were excessive in areas with large volumes and insufficient sound absorption. Speech intelligibility was generally adequate, but speech privacy was inadequate in shared and open-office areas, and into private offices with the doors open for ventilation. Improvement of the acoustical design of ‘green’ buildings must include increasing the external-internal noise isolation and that between workplaces, and the use of adequate sound absorption to control reverberation and noise.
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Zhiwei, Cheng, and Lu Yigang. "Diagnosis and analysis of abnormal noise in the pure electric vehicle’s air condition compressor at idle." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 4 (June 12, 2018): 711–24. http://dx.doi.org/10.1177/1461348418765950.
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A pure electric vehicle may produce an abnormal ‘clicking noise’ when idling, especially as start-up, which can be a serious problem in terms of product performance. In this paper: (1) professional evaluators carry out subjective evaluations and the abnormal noise-generation mechanism and its transfer path are analysed; (2) the mode shape and sound pressure distribution are both simulated using the finite element method; (3) the AC compressor’s sound source is identified and located in the main frequency domain using the acoustic array and image formation method, so vibration and interior vehicle noise measurements from the compressor are carried out; and (4) based on the established causes of the abnormal noise, three effective approaches – structure reinforcement, manufacturing process improvement and start-up control optimization – are presented to help prevent abnormal noises from the AC compressor.
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Pamungkas, Tri Cahyo Adi, and Sri Wiwoho Mudjanarko. "Traffic Management Of Air Transportation On Noise Control In The Area Around Juanda Airport." SPIRIT OF SOCIETY JOURNAL 4, no. 2 (March 31, 2021): 110–16. http://dx.doi.org/10.29138/scj.v4i2.1362.
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This study aims to determine (1) the level of noise in the area around Juanda Airport, (2) the perception of the community in the area around Juanda Airport about the comfort of life with noise, and (3) public perception of the discourse on implementing environmental management in the area around Juanda airport. The locations in this study are on Jalan Raya Sedati Gede (A1) and Jalan H. Abdul Rahman Sedati Gede (A2). The data collection technique used is the measurement technique with the help of a sound level meter for noise data collection, while the public perception data collection uses a questionnaire technique. The analysis technique used for public perception data is to use descriptive statistical tests. The results showed that (1) the measurement results in residential areas were in accordance with the Noise Level Quality Standard Decree of the Minister of Environment, Kep 48 / MENLH / 11/1996. November 25, 1996, for the locations of Jalan Raya Sedati Gede (A1) 77.48 dBA, and Jalan H. Abdul Rahman Sedati Gede (A2) 67.43 Dba above the noise quality standard threshold for settlements of 55 dBA. (2) The majority of the people around Juanda Airport agree that flight activities at Juanda airport cause noise that cause discomfort, rest, and cause stress. (3) The community in the area around Juanda Airport agreed to the need for environmental management as an effort to control noise.
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Polak, Krzysztof, and Jarosław Korzeb. "Identification of the Major Noise Energy Sources in Rail Vehicles Moving at a Speed of 200 km/h." Energies 14, no. 13 (July 1, 2021): 3957. http://dx.doi.org/10.3390/en14133957.
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In this work, the problematic identification of the main sources of noise occurring from the exploitation of railway vehicles moving at a speed of 200 km/h were analyzed. Within the conducted experimental research, the testing fields were appointed, measurement apparatus selected, and a methodology for conducting measurements was defined, including the assessment of noise on a curve and straight track for electric multiple units of the so-called Pendolino, an Alstom type ETR610 series ED25 train. The measurements were made using a microphone camera Bionic S-112 at a distance of 22 m from the track axis. As a result of the conducted experimental research, it was indicated that the noise resulting from vibrations arising at the wheel-rail contact (rolling noise) was the dominant source of sound.
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McLaren, Emma, and Charles Maxwell-Armstrong. "Noise Pollution on an Acute Surgical Ward." Annals of The Royal College of Surgeons of England 90, no. 2 (March 2008): 136–39. http://dx.doi.org/10.1308/003588408x261582.
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INTRODUCTION This study was undertaken to measure and analyse noise levels over a 24-h period on five general surgical wards. PATIENTS AND METHODS Noise levels were measured on three wards with four bays of six beds each (wards A, B and C), one ward of side-rooms only (ward D) and a surgical high dependency unit (ward E) of eight beds. Noise levels were measured for 15 min at 4-hourly intervals over a period of 24 h midweek. The maximum sound pressure level, baseline sound pressure level and the equivalent continuous level (LEq) were recorded. Peak levels and LEq were compared with World Health Organization (WHO) guidelines for community noise. Control measurements were taken elsewhere in the hospital and at a variety of public places for comparison. RESULTS The highest peak noise level recorded was 95.6 dB on ward E, a level comparable to a heavy truck. This exceeded all control peak readings except that recorded at the bus stop. Peak readings frequently exceeded 80 dB during the day on all wards. Each ward had at least one measurement which exceeded the peak sound level of 82.5 dB recorded in the supermarket. The highest peak measurements on wards A, B, C and E also exceeded peak readings at the hospital main entrance (83.4 dB) and coffee shop (83.4 dB). Ward E had the highest mean peak reading during the day and at night – 83.45 dB and 81.0 dB, respectively. Ward D, the ward of side-rooms, had the lowest day-time mean LEq (55.9 dB). Analysis of the LEq results showed that readings on ward E were significantly higher than readings on wards A, B and C as a group (P = 0.001). LEq readings on ward E were also significantly higher than readings on ward D (P < 0.001). Day and night levels differ significantly, but least so on the high dependency unit. CONCLUSIONS The WHO guidelines state that noise levels on wards should not exceed 30 dB LEq (day and night) and that peak noise levels at night should not exceed 40 dB. Our results exceed these guidelines at all times. It is likely that these findings will translate to other hospitals. Urgent measures are needed to rectify this.
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Sheridan, Linda, and Sophie Maluski. "Field Measurement and Criteria for Sound Insulation between Dwellings in Europe." Building Acoustics 7, no. 1 (March 2000): 31–40. http://dx.doi.org/10.1260/1351010001501480.
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Airborne and structure-borne sound transmission are the dominant noise paths in terraced, semi-detached houses and in multi-storey buildings, often causing annoyance when heard. They usually are controlled by applying building regulations before, during and after the construction of the dwellings. As part of a comparative study of the control and promotion of quality in housing in Europe, the acoustic quality in dwellings have been investigated for France, Norway, Sweden, the Netherlands, Germany, Switzerland, Italy and the United Kingdom. The study highlights many differences in regulations, criteria and methods of measurement. The conclusion drawn from this comparison is that there is no uniformity in the regulations for the acoustic quality of dwellings in Europe and much work is needed to establish uniformity.
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Pawełczyk, Marek, and Mariusz Latos. "Earplug Actuator Selection for a Miniature Personal Active Hearing Protection System." Archives of Acoustics 35, no. 2 (May 31, 2010): 213–22. http://dx.doi.org/10.2478/v10168-010-0020-6.
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AbstractThere are many industrial environments which are exposed to a high-level noise. It is necessary to protect people from the noise. Most of the time, the consumer requires a miniature version of a noise canceller to satisfy the internal working place requirements. Very important thing is to select the most appropriate personal hearing protection device, for example an earplug. It should guarantee high passive noise attenuation and allow for secondary sound generation in case of active control. In many cases the noise is nonstationary. For instance, some of the noisy devices are switched on and off, speed of some rotors or fans changes, etc. To avoid any severe transient acoustic effects due to potential convergence problems of adaptive systems, a fixed-parameter approach to control is appreciated. If the noise were stationary, it would be possible to design an optimal control filter minimising variance of the signal being the effect of the acoustic noise and the secondary sound interference. Because of noise nonstationarity for most applications, the idea of generalised disturbance defined by a frequency window of different types has been developed by the authors and announced in previous publications. The aim of this paper is to apply such an approach to different earplugs and verify its noise reduction properties. Simulation experiments are conducted based on real world measurements performed using the G. R. A. S. artificial head equipped with an artificial mechanical ear, and the noise recorded in a power plant.
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Koopmann, G. H., W. Neise, and K. A. Cunefare. "Fan Casing Noise Radiation." Journal of Vibration and Acoustics 113, no. 1 (January 1, 1991): 37–42. http://dx.doi.org/10.1115/1.2930152.
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This paper presents a method for assessing the extent of casing noise radiation of a centrifugal fan relative to the aeroacoustic sources associated with the inlet box of the fan. Central to the method is a boundary element program which is used to compute the acoustic pressures on the surfaces of the fan casing in terms of its surface vibration which in this case was measured experimentally. Data from an earlier experiment was used as the starting point for this study. Available data included sound pressure measurements near and away from the inlet box of the fan and vibration measurements over the casing of the fan. Noise from the outlet duct of the fan was purposely highly attenuated. Computations of sound pressure, intensity, and power indicated that, at the blade passing frequency (300 Hz), the aerodynamic sources generated near the entrance plane of the inlet box of the fan dominate the noise spectrum in the field. On the other hand, at the first subharmonic frequency of the blade tone (150 Hz), the sound power generated from the inlet box and fan casing are within 3 dB of each other. Thus, for effective noise control at this frequency, it would be necessary to include both noise sources in the overall treatment.
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Gök, Umut Murat, and Osman Taha Sen. "Development of a Unique Experimental System Investigating Vibroacoustic Characteristic of Geared Transmission Systems." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 1 (August 1, 2021): 5391–96. http://dx.doi.org/10.3397/in-2021-3080.
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Gearboxes are widely using in industry, especially in automotive transmission systems. In actual technology level, different component-based quality control methods are applied for the quality control of powertrains but test systems, designed for assembled products, are based on subjective evaluations and scalar measurement of total sound pressure. These systems, especially operating in industrial conditions where background noise is effective, cannot meet the technical requirements. In this paper, the development of a unique experimental platform, capable of testing the powertrain under real operating conditions (torque, rotational speeds), and the experimental results are explained. In the system where transmission error, noise and vibration measurements are carried out, defective samples were determined according to statistical evaluations and errors were classified. In future studies, using the ability to calculate mechanical efficiency based on measurements, the correlation between deviations in mechanical efficiency and transmission error will be examined.
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Schiller, J. D., C. Pape, and E. Reithmeier. "Aktiv gegen Lärm am Arbeitsplatz/Active Noise Control – Active against noise at work." Lärmbekämpfung 15, no. 03 (2020): 86–92. http://dx.doi.org/10.37544/1863-4672-2020-03-28.
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Lärm am Arbeitsplatz stellt eine ernst zunehmende Gesundheitsgefahr in vielen Berufsfeldern dar. Dies äußert sich bei Betroffenen z.B. in verminderter Konzentrationsleistung oder steigender Nervosität, kann aber auch bis zu einer irreversiblen Schädigung des Innenohrs führen. Daher gilt es, auftretenden Lärm und störende Hintergrundgeräusche an Arbeitsplätzen auf ein Minimum zu begrenzen. Das Institut für Mess- und Regelungstechnik (IMR) der Leibniz Universität Hannover forscht diesbezüglich an aktiven Systemen, die in der Lage sind, Lärm mittels zusätzlicher Kompensationslautsprecher zu dämpfen. Da derartige Systeme physikalisch bedingt stets lokale, räumlich begrenzte Wirkzonen (sog. Ruhezonen) aufweisen, ergeben sich beim Einsatz am sich bewegenden Menschen zahlreiche Schwierigkeiten. Forschungsschwerpunkt am IMR ist neben der Entwicklung der Schallsteuerung daher eine visuelle Ziel- und Bewegungserfassung des Menschen, in dessen Umgebung der Lärm gedämpft werden soll, sowie die Umsetzung einer geeigneten Reaktion auf detektierte Bewegungen. In Kombination kann so eine unterbrechungsfreie und bewegungsunabhängige Lärmreduktion gewährleistet werden. Für die experimentelle Validierung des entwickelten Systems wurde eigens ein neuartiger Prüfstand konstruiert, mittels dessen die Effektivität beim Einsatz am Menschen nachgewiesen werden konnte. Noise in the workplace is a serious health hazard in many occupational fields. This results in reduced concentration performance or increased nervousness, but can also lead to irreversible damage to the inner ear. It is therefore important to keep noise and disturbing background sounds at workplaces to a minimum. The Institute of Measurement and Automatic Control at Leibniz Universität Hannover is researching active systems that are capable of attenuating noise by means of additional compensating loudspeakers. As such systems always have local, spatially limited zones of action (so-called quiet zones) due to physical conditions, their use on individuals results in numerous difficulties. Besides the development of sound control systems, the research focus is therefore on the visual detection of the person in whose environment the noise is to be attenuated, as well as the implementation of a suitable reaction to detected movements. In combination, this can guarantee an interruption-free and motion-independent noise reduction. For the experimental validation of the developed system, a new type of test rig was constructed, which proved its effectiveness when used on humans.
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Felis, Józef, Andrzej Zbrowski, Tomasz Giesko, and Jordan Mężyk. "Structure Synthesis and Mechanical Parameters Choice for a Manipulating Mechanism for Acoustical Measurements in Anechoic Chamber." Solid State Phenomena 147-149 (January 2009): 13–18. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.13.
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The article presents the structural and geometric synthesis and mechanical parameter choice for a manipulation mechanism for measurement microphone positioning during acoustical tests in anechoic chamber. Usually the aims of acoustical measurements in anechoic chamber are: noise source Sound Power Level estimation, electroacoustical transducer directional characteristics measurement, sound diffusing characteristic of a structure measurement, measurement of Sound Pressure Level on a given measurement grid The specific of that kind of measurements brings up the need of measurement microphone positioning in many points of the measurement space accordingly to relevant standards. In most cases during the tests it is necessary to position the microphone in certain points on the hemisphere. In such cases utilizing of typical microphone stands impedes the measurement and extends the time needed for the tests. Those circumstances led to idea of measurement manipulator construction that would allow changing the microphone position during the measurement accordingly to a specified algorithm. The following assumptions for construction were taken: measurement microphone moves on the hemisphere with a maximal radius of 2 m, the weight of transported object (microphone or other) does not exceed 1 kg, positioning accuracy is 1 mm. Structural and geometric synthesis was made taking into account mounting conditions in anechoic chamber in Department of Mechanics and Vibroacoustics AGH-UST. There were several variants labored that fulfilled the assumptions. The choice of particular solution was made based on: • manipulator drives possible installation analysis with regard to their acoustical noise emission • structure stiffness analysis with regard to assumed positioning accuracy of the microphone Finally a modular construction of manipulator was chosen, which is composed of industrial turntable (built in the level of the wire netting) and two linear motion modules (long axis, short axis). That solution means that the device under test fixed on the turntable rotates in the range of 2π, and the measurement microphone moves on the track of one quarter of a circle. Specific angular position of the linear modules was chosen which allows minimal dimensions of linear modules. Simultaneously the control structure and the software part are developed. The usefulness of the manipulator will be definitely confirmed by a research that should evaluate the influence of the construction elements on the acoustical free field in an anechoic chamber.
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Iannace, Gino, Amelia Trematerra, and Giuseppe Ciaburro. "Case study: Automated recognition of wind farm sound using artificial neural networks." Noise Control Engineering Journal 68, no. 2 (March 20, 2020): 157–67. http://dx.doi.org/10.3397/1/376814.
Full textAbstract:
Wind energy has been one of the most widely used forms of energy since ancient times, with it being a widespread type of clean energy, which is available in mechanical form and can be efficiently transformed into electricity. However, wind turbines can be associated with concerns around noise pollution and visual impact. Modern turbines can generate more electrical power than older turbines even if they produce a comparable sound power level. Despite this, protests from citizens living in the vicinity of wind farms continue to be a problem for those institutions which issue permits. In this article, acoustic measurements carried out inside a house were used to create a model based on artificial neural networks for the automatic recognition of the noise emitted by the operating conditions of a wind farm. The high accuracy of the models obtained suggests the adoption of this tool for several applications. Some critical issues identified in a measurement session suggest the use of additional acoustic descriptors as well as specific control conditions.
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Zheng, Hao, Fuwu Yan, Chihua Lu, Fengxiang Xu, Qiuyue Li, and Wei Tian. "Optimization design of the valve spring for abnormal noise control in a single-cylinder gasoline engine." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 2 (August 5, 2016): 204–13. http://dx.doi.org/10.1177/0954407016651180.
Full textAbstract:
To address the abnormal noise problem of single-cylinder gasoline engines in the idle condition, acoustic spectral and intensity analysis was carried out. Then the noises were identified as valve impact noises caused by the anomalous dynamic performance of the engine valve mechanism. To improve further the dynamic performance of the mechanism by optimization of the valve spring, a multi-body dynamic model of the valve mechanism was developed on the basis of the key performance and the structure parameters of the valve spring. By using the optimization strategy, the oscillation amplitude of the valve spring and the valve impact force can be reduced by about 62.5% and 27% respectively. Finally, optimized sample pieces were produced for acoustic verification tests. The obtained results showed that the engine’s overall working noise was reduced by about 2.0 dB(A), and the sound quality of the engine was determined using both objective measurements and subjective evaluation of the noise, vibration and harshness performance. It can be concluded that the valve impact noise can be reduced by optimization of the valve springs.