Academic literature on the topic 'Natural Noise'
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Journal articles on the topic "Natural Noise"
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Hegarty, Paul. "Noise threshold: Merzbow and the end of natural sound." Organised Sound 6, no. 3 (2001): 193–200. http://dx.doi.org/10.1017/s1355771801003053.
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When we ask what noise is, we would do well to remember that no single definition can function timelessly - this may well be the case with many terms, but one of the arguments of this essay is that noise is that which always fails to come into definition. Generally speaking, noise is taken to be a problem: unwanted sound, unorganised sound, excessively loud sound. Metaphorically, when we hear of noise being generated, we understand it to be something extraneous. Historically, though, noise has just as often signalled music, or pleasing sound, as its opposite. In the twentieth century, the notion of a clear line between elements suitable for compositional use (i.e. notes, created on instruments) and the world of noises was broken down. Russolo's ‘noisy machines’, Varèse and Satie's use of ostensibly non-musical machines to generate sounds, musique concrète, Cage's rethinking of sound, noise, music, silence . . .
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Jaafar, Haryati, and Dzati Athiar Ramli. "Effect of Natural Background Noise and Man-Made Noise on Automated Frog Calls Identification System." Journal of Tropical Resources and Sustainable Science (JTRSS) 3, no. 1 (2021): 208–13. http://dx.doi.org/10.47253/jtrss.v3i1.559.
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Frog identification based on their calls becomes important for biological research and environmental monitoring. However, identifying particular frog calls becomes challenging particularly when the frog calls are interrupted with noises either in natural background noise or man-made noise. Hence, an automatic identification frog call system that robust in noisy environment has been proposed in this paper. Experimental studies of 675 audio obtained from 15 species of frogs in the Malaysian forest and recorded in an outdoor environment are used in this study. These audio data are then corrupted by 10dB and 5dB noise. A syllable segmentation technique i.e. short time energy (STE) and Short Time Average Zero Crossing Rate (STAZCR) and feature extraction, Mel-Frequency Cepstrum Coefficients (MFCC) are employed to segment the desired syllables and extract the segmented signal. Subsequently, the Local Mean k-Nearest Neighbor with Fuzzy Distance Weighting (LMkNN-FDW) are employed as a classifier in order to evaluate the performance of the identification system. The experimental results show both of natural background noise and man-made noise outperform by 95.2% and 88.27% in clean SNR, respectively.
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Jiang, Tinglei, Xiong Guo, Aiqing Lin, et al. "Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication." Animal Cognition 22, no. 2 (2019): 199–212. https://doi.org/10.5281/zenodo.13454176.
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(Uploaded by Plazi for the Bat Literature Project) Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.
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Jiang, Tinglei, Xiong Guo, Aiqing Lin, et al. "Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication." Animal Cognition 22, no. 2 (2019): 199–212. https://doi.org/10.5281/zenodo.13454176.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.
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Jiang, Tinglei, Xiong Guo, Aiqing Lin, et al. "Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication." Animal Cognition 22, no. 2 (2019): 199–212. https://doi.org/10.5281/zenodo.13454176.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.
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Jiang, Tinglei, Xiong Guo, Aiqing Lin, et al. "Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication." Animal Cognition 22, no. 2 (2019): 199–212. https://doi.org/10.5281/zenodo.13454176.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.
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Jiang, Tinglei, Xiong Guo, Aiqing Lin, et al. "Bats increase vocal amplitude and decrease vocal complexity to mitigate noise interference during social communication." Animal Cognition 22, no. 2 (2019): 199–212. https://doi.org/10.5281/zenodo.13454176.
Full textAbstract:
(Uploaded by Plazi for the Bat Literature Project) Natural background noises are common in the acoustic environments in which most organisms have evolved. Therefore, the vocalization and sound perception systems of vocal animals are inherently equipped to overcome natural background noise. Human-generated noises, however, pose new challenges that can hamper audiovocal communication. The mechanisms animals use to cope with anthropogenic noise disturbances have been extensively explored in a variety of taxa. Bats emit echolocation pulses primarily to orient, locate and navigate, while social calls are used to communicate with conspecifics. Previous studies have shown that bats alter echolocation pulse parameters in response to background noise interference. In contrast to high-frequency echolocation pulses, relatively low-frequency components within bat social calls overlap broadly with ambient noise frequencies. However, how bats structure their social calls in the presence of anthropogenic noise is not known. Here, we hypothesized that bats leverage vocal plasticity to facilitate vocal exchanges within a noisy environment. To test this hypothesis, we subjected the Asian particolored bat, Vespertilio sinensis, to prerecorded traffic noise. We observed a significant decrease in vocal complexity (i.e., an increased frequency of monosyllabic calls) in response to traffic noise. However, an increase in the duration and frequency of social calls, as have been observed in other species, was not evident. This suggests that signal simplification may increase communication efficacy in noisy environments. Moreover, V. sinensis also increased call amplitude in response to increased traffic noise, consistent with the predictions of the Lombard effect.
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Lee, Songmi, Dokyeong Kim, and Jongkwan Ryu. "Effect of Added Natural and Artificial Sounds on Emotional Response and Indoor Soundscape to Residential Noises." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, no. 1 (2023): 7086–91. http://dx.doi.org/10.3397/in_2023_1061.
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This study investigated the effect of added natural and artificial sounds on emotional responses due to residential noises. The laboratory experiment conducted on three residential noise sources (child jumping and plumbing from upper unit and air conditioner outdoor unit) with different sound spectrum and temporal characteristics. In addition, combined sounds with residential, natural (one birdsong and three water sounds of waterfall, sea wave, and stream) and artificial sound (brown and white noise) were set. The experiment consisted of two sessions; self-assessment manikin and indoor soundscape assessment for each sound sources (single and combined residential noises) presented by headphone and woofer. As a result, most combined natural and artificial sounds resulted in more positive changes (higher valence and lower arousal score) than single residential noise. Among combined sounds, multiple natural sound (birdsong + stream) with residential noise showed significant difference from single residential noises such as air conditioner outdoor unit and plumbing noise. Meanwhile, eight affective attribute scale for indoor soundscape assessment showed two main perceptual dimensions and most added natural and artificial sounds had a role in increasing comfort.
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Luo, Chenhong, Yong Wang, Bo Li, Hanyang Liu, Pengyu Wang, and Leo Yu Zhang. "An Efficient Approach to Manage Natural Noises in Recommender Systems." Algorithms 16, no. 5 (2023): 228. http://dx.doi.org/10.3390/a16050228.
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Recommender systems search the underlying preferences of users according to their historical ratings and recommend a list of items that may be of interest to them. Rating information plays an important role in revealing the true tastes of users. However, previous research indicates that natural noises may exist in the historical ratings and mislead the recommendation results. To deal with natural noises, different methods have been proposed, such as directly removing noises, correcting noise by re-predicting, or using additional information. However, these methods introduce some new problems, such as data sparsity and introducing new sources of noise. To address the problems, we present a new approach to managing natural noises in recommendation systems. Firstly, we provide the detection criteria for natural noises based on the classifications of users and items. After the noises are detected, we correct them with threshold values weighted by probabilities. Experimental results show that the proposed method can effectively correct natural noise and greatly improve the quality of recommendations.
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Ávila Ferreira, Vinícius. "Soundproof Window - Natural Ventilation." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 3 (2021): 3294–304. http://dx.doi.org/10.3397/in-2021-2361.
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Expansion of brasilians cities worsen noise pollution in these places, forcing people to maintain their doors and windows closed. Domestic environment enclosing lead to necessity of air conditioning system, however the frequent use of the equipment may cause many health problems, such as respiratory difficulties and spread of diseases , not to mention high costs with energy. Considering these facts, there is the need of soundproofing windows with air supply , that allows passage of air without noise passage, guarantee a well-ventilated environment, with thermic and acoustic comfort without the use of acclimatisation systems . we have developed two prototypes with significant opening that allows air supply (passage) (0,35m2) and noise reduction (Rw+Ctr) reaching 8 to 10 dB. In the first study, we considered people inhabiting really noisy surrounding areas, who has already installed a regular window. In this particular case, we developed a soundproofing window air supply that can be installed over the existing one. A second study considered new constructions to focus the environment where the person sleeps and then elaborate a soundproofing window air supply for bedrooms.
Dissertations / Theses on the topic "Natural Noise"
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Reed, Veronica Arlene. "Natural and Experimental Noise Affects Acoustic Communication in Songbirds." DigitalCommons@CalPoly, 2021. https://digitalcommons.calpoly.edu/theses/2279.
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Background noise is ubiquitous and can impair acoustic communication and influence signaling behavior in animals. Despite evidence demonstrating myriad effects of anthropogenic noise on animal communication, precisely how natural background noise influences communication and behavior remains unclear. Yet, natural sources of background noise, such as rushing rivers or crashing ocean surf, share similar power spectra to sources of anthropogenic noise and can occur at high amplitudes, potentially masking acoustic signals.
To investigate the effects of water-generated noise on songbird behavior, we experimentally broadcast landscape-level playbacks of ocean surf and river noise in coastal California, USA, and riparian habitat in Idaho, USA, respectively. In Chapter 1, we conducted a conspecific playback experiment examining how territorial defense behaviors of lazuli buntings (Passerina amoena) and spotted towhees (Pipilo maculatus) vary in response to broadcast water noise. We also incorporated cicada noise from a serendipitous Okanagana spp. emergence as a biotic source influencing lazuli bunting behavior. Both species produce songs that share substantial spectral overlap with low-frequency, water-generated noise, and lazuli bunting song shares an additional high-frequency overlap with cicada calls. Thus, there is potential for background acoustic conditions to mask conspecific signals. We found that detection and discrimination of conspecific playback occurred more slowly for both species as sound level increased. Lazuli buntings also exhibited divergent flight behaviors in response to high- and low-frequency acoustic sources, both dependent and independent of sound level.
In Chapter 2, we investigated how amplitude and frequency of water-generated noise influences spectral and temporal song characteristics in six songbird species. We recorded individuals defending territories across 37 sites, with each site representing one of four acoustic environments: naturally quiet ‘controls’, naturally noisy ‘positive controls’ adjacent to the ocean or a whitewater river, ‘phantom’ playback sites with continuous broadcast of low-frequency water noise, and ‘shifted’ playback sites with continuous broadcast of high-frequency water noise. We predicted that all individuals exposed to ‘positive control’, ‘phantom’, or ‘shifted’ noise would adjust song structure, but the magnitude of signal modification would be larger in noisier locations and the type of modification would depend on the spectral profile of the acoustic environment. No two species altered songs in precisely the same way. However, song structure of all six species varied with amplitude and/or frequency of background noise.
Together our results demonstrate that natural noise can impair agonistic behaviors and influence vocal structure. These findings suggest that the natural acoustic environment shapes acoustic communication, highlighting natural soundscapes as an under-appreciated axis of the environment.
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Alvarsson, Jesper J. "Stress recovery during exposure to natural sounds and environmental noise." Thesis, Stockholm University, Department of Psychology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-27894.
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<p>Research suggests that physiological stress reactions may be reduced by visual impressions from natural environments as compared to urban or built-up environments. The present experiment tested whether similar effects might be found by auditory stimulation. Forty university students were tested in an experiment with four consecutive recovery sessions after stressful mental arithmetic tests. The independent variables were type of sound during recovery. The sound was either a natural sound environment (sounds from water and birdsong, at 50 dBA), or three types of noisy environments (traffic noises at 50 or 80 dBA or ambient background sound at 40 dBA). The main dependent variables were physiological recovery from stress, as measured by decrease in heart rate (HR) and skin conductance level (SCL) after the stressful arithmetic test. The main result was that SCL reduction was faster during nature sounds than during the various noises. For HR, no systematic effects of experimental sounds were found. The result for SCL lends some support the hypothesis that exposure to natural sounds facilitate physiological stress recovery.</p><br>Sarcade
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Bolin, Karl. "Wind Turbine Noise and Natural Sounds : Masking, Propagation and Modeling." Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10434.
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Wind turbines are an environmentally friendly and sustainable power source. Unfortunately, the noise impact can cause deteriorated living conditions for nearby residents. The audibility of wind turbine sound is influenced by ambient sound. This thesis deals with some aspects of noise from wind turbines. Ambient sounds influence the audibility of wind turbine noise. Models for assessing two commonly occurring natural ambient sounds namely vegetation sound and sound from breaking waves are presented in paper A and B. A sound propagation algorithm has been compared to long range measurementsof sound propagation in paper C. Psycho-acoustic tests evaluating the threshold and partial loudness of wind turbine noise when mixed with natural ambient sounds have been performed. These are accounted for in paper D. The main scientific contributions are the following.Paper A: A semi-empiric prediction model for vegetation sound is proposed. This model uses up-to-date simulations of wind profiles and turbulent wind fields to estimate sound from vegetation. The fluctuations due to turbulence are satisfactory estimated by the model. Predictions of vegetation sound also show good agreement to measured spectra. Paper B: A set of measurements of air-borne sound from breaking waves are reported. From these measurements a prediction method of sound from breaking waves is proposed. Third octave spectra from breaking waves are shown to depend on breaker type. Satisfactory agreement between predictions and measurements has been achieved. Paper C: Long range sound propagation over a sea surface was investigated. Measurements of sound transmission were coordinated with local meteorological measurements. A sound propagation algorithm has been compared to the measured sound transmission. Satisfactory agreement between measurements and predictions were achieved when turbulence were taken into consideration in the computations. Paper D: The paper investigates the interaction between wind turbine noise and natural ambient noise. Two loudness models overestimate the masking from two psychoacoustic tests. The wind turbine noise is completely concealed when the ambient sound level (A-weighed) is around 10 dB higher than the wind turbine noise level. Wind turbine noise and ambient noise were presented simultaneously at the same A-weighed sound level. The subjects then perceived the loudness of the wind turbine noise as 5 dB lower than if heard alone. Keywords: Wind turbine noise, masking, ambient noise, long range sound propagation<br>QC 20100705
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Ceylan, Ciwan. "Conditional Noise-Contrastive Estimation : With Application to Natural Image Statistics." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-213847.
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Unnormalised parametric models are an important class of probabilistic models which are difficult to estimate. The models are important since they occur in many different areas of application, e.g. in modelling of natural images, natural language and associative memory. However, standard maximum likelihood estimation is not applicable to unnormalised models, so alternative methods are required. Noise-contrastive estimation (NCE) has been proposed as an effective estimation method for unnormalised models. The basic idea is to transform the unsupervised estimation problem into a supervised classification problem. The parameters of the unnormalised model are learned by training the model to differentiate the given data samples from generated noise samples. However, the choice of the noise distribution has been left open to the user, and as the performance of the estimation may be sensitive to this choice, it is desirable for it to be automated. In this thesis, the ambiguity in the choice of the noise distribution is addressed by presenting the previously unpublished conditional noise-contrastive estimation (CNCE) method. Like NCE, CNCE estimates unnormalised models by classifying data and noise samples. However, the choice of noise distribution is partly automated via the use of a conditional noise distribution that is dependent on the data. In addition to introducing the core theory for CNCE, the method is empirically validated on data and models where the ground truth is known. Furthermore, CNCE is applied to natural image data to show its applicability in a realistic application.<br>Icke-normaliserade parametriska modeller utgör en viktig klass av svåruppskattade statistiska modeller. Dessa modeller är viktiga eftersom de uppträder inom många olika tillämpningsområden, t.ex. vid modellering av bilder, tal och skrift och associativt minne. Dessa modeller är svåruppskattade eftersom den vanliga maximum likelihood-metoden inte är tillämpbar på icke-normaliserade modeller. Noise-contrastive estimation (NCE) har föreslagits som en effektiv metod för uppskattning av icke-normaliserade modeller. Grundidén är att transformera det icke-handledda uppskattningsproblemet till ett handlett klassificeringsproblem. Den icke-normaliserade modellens parametrar blir inlärda genom att träna modellen på att skilja det givna dataprovet från ett genererat brusprov. Dock har valet av brusdistribution lämnats öppet för användaren. Eftersom uppskattningens prestanda är känslig gentemot det här valet är det önskvärt att få det automatiserat. I det här examensarbetet behandlas valet av brusdistribution genom att presentera den tidigare opublicerade metoden conditional noise-contrastive estimation (CNCE). Liksom NCE uppskattar CNCE icke-normaliserade modeller via klassificering av data- och brusprov. I det här fallet är emellertid brusdistributionen delvis automatiserad genom att använda en betingad brusdistribution som är beroende på dataprovet. Förutom att introducera kärnteorin för CNCE valideras även metoden med hjälp av data och modeller vars genererande parametrar är kända. Vidare appliceras CNCE på bilddata för att demonstrera dess tillämpbarhet.
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Yang, Hong-Seok. "Outdoor noise control by natural/sustainable materials in urban areas." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4484/.
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This study explores the effects of natural and sustainable materials including vegetation, green roof systems and green walls on outdoor noise control in urban areas. The concept of this study starts with a hypothesis that well-planned use of the natural materials on building and urban surfaces can achieve useful reductions in noise levels and reverberation in urban spaces. Firstly, this study examines random-incidence absorption and scattering coefficients of vegetation through a series of measurements in a reverberation chamber in order to characterise the effects of various designable factors such as soil depths, soil water content and vegetation densities. This data is used later in acoustic computer simulations. To quantify the scattering effect of trees and to allow including it in numerical predictions, a series of measurements are carried out for individual trees in an open field. Green roof systems are placed on a low profiled structure to examine sound transmission through the vegetated low barrier. To suggest noise abatement schemes in relatively small urban spaces, the acoustic effects of landscape designs using vegetation in a courtyard are studied through a case study. As a preliminary study on the noise reduction effect of vegetation in relatively large urban spaces, field measurements are carried out at outdoor spaces in high-rise apartment complexes. Based on the measurement results, the noise reduction effect of vegetation in apartment complexes is also predicted. The overall results for each research topic can be summarised as follows: It is shown that low-growing vegetation can be an effective measure for absorbing/scattering sound energy, especially at high frequencies. Results of field measurements show that tree reverberation exerts an influence only on frequencies above 1 kHz. At 4 kHz, RT (reverberation time) can be as long as 0.28 sec. Measurements made near the same deciduous tree with and without leaves indicate that leaves increase reverberation at 4 kHz by 0.08 sec. The results on sound transmission over the low barrier with green roof systems suggest that SPL attenuation increases with the increasing green roof areas. The extra SPL (sound pressure level) attenuation caused by green roof systems could be up to 9.5 dB at certain frequencies. With well-planned application of landscape designs in a courtyard, speech levels and RT at 500 Hz are decreased by 9.3 dBA and 81 %, respectively. In outdoor spaces of apartment complexes, RT is generally rather long, over 4 sec at 500 Hz, influenced by many factors such as openness, source-receiver distance and building height. In terms of SPL distribution, the measured SPL is up to 8 dB higher compared to the semi-free field situation. It is also found that vegetation at the apartment complex can be effective in reducing RT by 0.95 sec (46 % decrease).
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Dong, Li. "Noise level estimation from single image based on natural image statistics." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3952094.
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Saxen, Shelley Walker. "Park visitors and the natural soundscape : winter experience dimensions in yellowstone." [Missoula, Mont.] : The University of Montana, 2008. http://etd.lib.umt.edu/theses/available/etd-12112008-123204/unrestricted/umi-umt-1108.pdf.
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Thesis (Ph.D.) --University of Montana, 2008.<br>Title from author supplied metadata. Description based on contents viewed on May 15, 2009. ETD number: etd-12112008-123204. Author supplied keywords: natural sounds ; recreation ; visitor experiences ; national park policy ; soundscape policy ; soundscape management ; winter visitor experiences ; wildland recreation. Includes bibliographical references.
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Lögdberg, Frida. "Population dynamics in variable environments – impacts of noise colour and synchrony." Doctoral thesis, Linköpings universitet, Teoretisk Biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-72951.
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Environmental variation is an essential part of population dynamics, and two characteristics of such variation—variance and the temporal autocorrelation termed ‘noise colour’—are essential for determining the persistence of a population. In addition, the spatial correlation of local environmental variation between habitat patches (i.e., synchrony) is equally important in subdivided populations connected via dispersal. The research underlying this thesis explored the effects of noise colour and synchrony on population dynamics. The dynamics were studied primarily in single-species models with fast or slow population responses to environmental changes, and several-species systems (i.e., food webs) with different stability properties were also considered. Populations were spatially subdivided with local dynamics in discrete patches, and patch positions were modelled either implicitly or explicitly, with different landscape configurations in the latter case. It has previously been shown that the effect of increased environmental redness on extinction risk in nonspatial models depends on population responsiveness, seen as increased and decreased risks for fast and slow responding populations, respectively. Here, increased redness of noise decreased the extinction risk for fast-responding populations (in accordance with non-spatial studies) in a simple implicit landscape model (Papers I and II). Slow-responding populations in some cases showed a raised extinction risk for intermediate noise colour values (Paper I), which does not agree with earlier results. However, increasing the spatial complexity evened out the differences that were caused by responsiveness (Papers III and IV). Thus, in general, the explicit landscape models displayed a decrease in extinction risk with increasing environmental redness regardless of whether the populations were fast or slow in responding to environmental variation. Still, fast and slow responsiveness of populations differed in relation to the following: overall levels of extinction risk (Papers I, III, and IV), synchrony of population variations (Paper II), colour of population variations (Paper II), and response to landscape structure (Papers III and IV). For fast-responding populations, the degree of synchrony of population variations was similar to the synchrony of environmental noise (Paper II). Local populations of a model organism that responded slowly to environmental variation were more synchronized than the environmental variation itself, and the largest shift between the environment and the populations was seen for intermediate red noise colours (Paper II). This indicated that dispersal-induced population synchrony could be enhanced by reddened noise. Landscape configuration proved to be important for the general levels of extinction risk. This effect was most pronounced for fast-responding populations (Papers III and IV) and became even more distinct when distance-dependent synchrony was added between the environmental variations (Paper IV). Adding explicit landscapes led to an decrease in the differences between fast- and slow-responding populations, when considering the influence of noise colour on extinction risk. Also, landscape configuration affected the importance of degree of synchrony through its impact on distances between patches, which resulted in configurations where extinction risk depended solely on noise colour. The effects on stability exerted by populations embedded in food webs were investigated in an implicit landscape model (Paper V). Three types of food webs with different properties of inherent stability all showed a decrease in stability at increased environmental variance and increased redness of environmental variation. In conclusion, the single-species models showed that the survival conditions of populations that were near extinction were improved by all of the following: decreased synchrony, reddening of noise, and aggregation of patches. The results of the web simulations indicate that we need better understanding of how findings obtained using single-species models can be used to reveal the effects of noise colour on species communities. From a management perspective, altering landscape structure may compensate for increased extinction risks caused by changed noise colour of environmental variation, which is a predicted outcome of climate change.
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Serban, Adriana. "Ultra-Wideband Low-Noise Amplifier andSix-Port Transceiver for High Speed DataTransmission." Doctoral thesis, Linköpings universitet, Fysik och elektroteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-52954.
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Today’s data rates in wired networks can reach 100 Gbit/s using optical fiber while data rates in wireless networks are much lower - tens of Mbit/s for 3G mobile communication and 480 Mbit/s for ultra-wideband (UWB) short range wireless communications. This difference in data rates can mainly be explained by the limited allowed frequency spectrum, the nature of the radio signal and the high requirements imposed on all hardware designed for high speed and wideband wireless communications. However, the demand on wireless commercial applications at competitive costs is growing. The first step in regulations allowing higher data rates for wireless communications was taken in 2002, when the Federal Communication Commission (FCC) in USA released unlicensed the 3.1-10.6 GHz frequency band restricting only the power level (maximum mean equivalent isotropic radiated power density of a UWB transmitter is -41.3 dBm/MHz) in the band 3.1-10.6 GHz. But Europe, Japan and recently China have put additional restrictions on the 3.1-4.8 GHz band. The restrictions address the problems that have raised from the coexistence and colocation of the UWB systems with other narrowband wireless systems. Thus, the 6-9 GHz band combined with an increased modulation order scheme is of large interest. Operating at higher frequency and wider bandwidth than today’s communication technologies, with the general task of maximizing the wireless data rate while keeping the power consumption low, requires new communication system solutions and new circuit design approaches. These new solutions also require understanding of many multi-disciplinary areas which until the recent past were not directly related: from classic analog circuit design to microwave design, from modulation techniques to radio system architecture. In this thesis, new design techniques for wide bandwidth circuits above 3 GHz are presented. After focusing on ultra-wideband low-noise amplifier (UWB LNA) design for low-power and low-cost applications, the practical implementation and measurement of a 3.1-4.8 GHz UWB LNA is addressed. Passive distributed components of microstrip transmission lines are intensively used and their contribution to the UWB LNA performance is studied. In order to verify the design methodology while extending it to the UWB radio front-end, the UWB LNA is integrated on the same substrate with a pre-selecting filter with the frequency multiplexing function. In this way, the concept of frequencytriplexed UWB front-end is demonstrated for the Mode 1 multi-band UWB bandwidth 3.1-4.8 GHz. Using the proposed receiver front-end topology, better receiver sensitivity and selective operation can be achieved. The later part of the thesis investigates ultra-wideband 6-9 GHz receiver and transmitter front-end topologies for Gbit/s data rates and low power consumption. To capture the advantages offered by distributed passive components, both the transmitter and receiver use the six-port correlator as the core of a passive mixer. Modelling and design of the 6-9 GHz UWB front-end transceiver include different receiver topologies and different modulation schemes. Finally, the 7.5 GHz UWB transceiver front-end is implemented and evaluated. Measurement results confirm the large potential of the six-port UWB front-end to achieve multiple Gbit/s data rates. This may open for future solutions to meet the continuous challenge of modern communication systems: higher data rates at low power consumption and low cost.
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Kight, Caitlin Rebecca. "Acoustics of anthropogenic habitats: The impact of noise pollution on eastern bluebirds." W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539616712.
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An increasing number of habitats are affected by anthropogenic noise pollution, which is often louder, has a different frequency emphasis, and may occur over a different temporal scale, than natural noise. An increasing number of studies indicate that acoustically-communicating animals in such areas can modify their vocalizations in order to make themselves heard over the noise, but many questions still remain, including: How taxonomically widespread is vocal flexibility in response to anthropogenic noise, and do all vocally flexible species employ the same mechanisms to escape acoustic masking? Are there fitness repercussions for living, communicating, and breeding in noisy habitats? and, can particular habitat features be used to predict environmental noise levels and sound propagation characteristics? Here, I present data collected from the breeding territories of eastern bluebirds (Sialia sialis ) to address each of these questions. My results add another species to the list of those who are able to avoid acoustic masking by modifying temporal and spectral traits of vocalizations. I also show that anthropogenic noise is associated with changes in several eastern bluebird breeding parameters. Finally, I demonstrate that both anthropogenic noise levels and sound propagation traits can be predicted by particular habitat characteristics.
Books on the topic "Natural Noise"
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Corner, Philip. 3 for Phyllis for some things: Mostly natural noise sounds. Frog Peak Music, 2009.
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Spaulding, A. D. The natural and man-made noise environment in personal communications bands. U.S. Department of Commerce, National Telecommunications and Information Administration], 1996.
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R, Kerman B., and Conference on Natural Physical Sources of Underwater Sound (1990 : Cambridge, England), eds. Natural physical sources of underwater sound: Sea surface sound (2). Kluwer Academic Publishers, 1993.
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Kerman, B. R. Natural physical sources of underwater sound: Sea surface sound (2). Springer Science, 1993.
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Terekhov, A. L. Borʹba s shumom na kompressornykh stant͡s︡ii͡a︡kh. "Nedra," Leningradskoe otd-nie, 1985.
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Spaulding, A. D. The natural and man-made noise environment in personal communications services bands. U.S. Department of Commerce, National Telecommunications and Information Administration, 1996.
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Kerman, B. R. Sea Surface Sound: Natural Mechanisms of Surface Generated Noise in the Ocean. Springer Netherlands, 1988.
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Spaulding, A. D. The natural and man-made noise environment in personal communications services bands. U.S. Department of Commerce, National Telecommunications and Information Administration, 1996.
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United States. National Telecommunications and Information Administration, ed. The natural and man-made noise environment in personal communications services bands. U.S. Dept. of Commerce, National Telecommunications and Information Administration, 1996.
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Spaulding, A. D. The natural and man-made noise environment in personal communications services bands. U.S. Department of Commerce, National Telecommunications and Information Administration, 1996.
Find full textBook chapters on the topic "Natural Noise"
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Thorne, P. D. "Seabed Saltation Noise." In Natural Physical Sources of Underwater Sound. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1626-8_54.
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Katada, Naofumi, and Haruhiko Nishimura. "Noise Effects on Chaos in Chaotic Neuron Model." In Natural Computing. Springer Japan, 2010. http://dx.doi.org/10.1007/978-4-431-53868-4_24.
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Martínez, Luis, Jorge Castro, and Raciel Yera. "Managing Natural Noise in Recommender Systems." In Theory and Practice of Natural Computing. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-49001-4_1.
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Longuet-Higgins, M. S. "Bubble Noise Mechanisms — A Review." In Natural Physical Sources of Underwater Sound. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1626-8_33.
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Pumphrey, H. C. "Sources of Underwater Rain Noise." In Natural Physical Sources of Underwater Sound. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1626-8_51.
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Copeland, G. J. M. "Low Frequency Ambient Noise – Generalised Spectra." In Natural Physical Sources of Underwater Sound. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1626-8_2.
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Carey, William M., and James W. Fitzgerald. "Low Frequency Noise from Breaking Waves." In Natural Physical Sources of Underwater Sound. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1626-8_22.
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Kaur, Jaipreet, and Rajdeep Singh Sohal. "Noise Estimation and Removal in Natural Language Processing." In Handbook of Vibroacoustics, Noise and Harshness. Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-4638-9_38-1.
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Kaur, Jaipreet, and Rajdeep Singh Sohal. "Noise Estimation and Removal in Natural Language Processing." In Handbook of Vibroacoustics, Noise and Harshness. Springer Nature Singapore, 2024. https://doi.org/10.1007/978-981-97-8100-3_38.
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Dyer, Ira. "Source Mechanisms for Arctic Ocean Ambient Noise." In Natural Physical Sources of Underwater Sound. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1626-8_40.
Full textConference papers on the topic "Natural Noise"
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Kawasaki, Z.-I., and M. Hayakawa. "Terrestrial and Planetary Natural EM Noise." In 11th International Zurich Symposium and Technical Exhibition on Electromagnetic Compatibility. IEEE, 1995. https://doi.org/10.23919/emc.1995.10784173.
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Nickolaenko, A. P., and D. D. Iudin. "Hurst Exponent Derived for Natural ELF Electromagnetic Noise." In EMC_2000_Wroclaw. IEEE, 2000. https://doi.org/10.23919/emc.2000.10842156.
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Covino, Bernard S., Sophie J. Bullard, Stephen D. Cramer, et al. "Evaluation of the Use of Electrochemical Noise Corrosion Sensors for Natural Gas Transmission Pipelines." In CORROSION 2004. NACE International, 2004. https://doi.org/10.5006/c2004-04157.
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Abstract Corrosion sensors and electrochemistry-based corrosion measurement technology were used to study internal corrosion of environments similar to those in natural gas transmission pipelines. Field tests were conducted at a gas gathering site. Test locations were selected in environments consisting of dry/moist natural gas and the hydrocarbon/water mixture removed from natural gas. Sensors were made using A106 pipeline steel in the form of flange probes. Linear polarization resistance, electrochemical noise, and harmonic distortion analysis were used to measure corrosion rates, Stern-Geary constants, and pitting factors. Results show that the measurements were sensitive enough to detect small rates of corrosion in the selected environments.
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Bullard, Sophie J., Bernard S. Covino, Stephen D. Cramer, et al. "Electrochemical Noise Monitoring of Corrosion in Natural Gas Production Plants." In CORROSION 2005. NACE International, 2005. https://doi.org/10.5006/c2005-05359.
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Abstract A test spool containing two sets of sensors has been inserted in a high pressure environment of a natural gas production plant. The two flange-type sensors are configured so that moisture was more likely to accumulate at one than the other. Electrochemical noise (EN), linear polarization resistance (LPR), and harmonic distortion analysis (HDA) are used in combination to monitor the corrosion occurring in the plant. The 100-day corrosion data for the vertical and horizontal sensors show that corrosion rates were low and averaged ~0.0055 mm/yr. The measured B values were 0.035 V for the vertical sensor and 0.033V for the horizontal sensor, higher than the typical assume value of 0.026 V. The pitting factors were similar between the two sensors except that the vertical set had a prolonged higher pitting factor of 0.1 at the initiation of the test.
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Wang, Yixuan, Xianzhen Luo, Fuxuan Wei, et al. "Make Some Noise: Unlocking Language Model Parallel Inference Capability through Noisy Training." In Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing. Association for Computational Linguistics, 2024. http://dx.doi.org/10.18653/v1/2024.emnlp-main.718.
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Cai, Xiumei, Rui Zhang, and Chenmao Wu. "Robust subspace clustering image segmentation algorithm based on noise suppression." In 2024 6th International Conference on Natural Language Processing (ICNLP). IEEE, 2024. http://dx.doi.org/10.1109/icnlp60986.2024.10692555.
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Al-Laith, Ali, Daniel Hershcovich, Jens Bjerring-Hansen, Jakob Ingemann Parby, Alexander Conroy, and Timothy R. Tangherlini. "Noise, Novels, Numbers. A Framework for Detecting and Categorizing Noise in Danish and Norwegian Literature." In Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing. Association for Computational Linguistics, 2024. http://dx.doi.org/10.18653/v1/2024.emnlp-main.196.
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ATTENBOROUGH, K. "NATURAL NOISE CONTROL." In Inter-Noise 1996. Institute of Acoustics, 2024. http://dx.doi.org/10.25144/19553.
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Brummer, Benoit, and Christophe De Vleeschouwer. "Natural Image Noise Dataset." In 2019 IEEE/CVF Conference on Computer Vision and Pattern Recognition Workshops (CVPRW). IEEE, 2019. http://dx.doi.org/10.1109/cvprw.2019.00228.
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BOERSMA, HF, and RS ETIENNE. "CHARACTERIZATION OF THE NATURAL AMBIENT SOUND ENVIRONMENT." In Inter-Noise 1996. Institute of Acoustics, 2024. http://dx.doi.org/10.25144/19462.
Full textReports on the topic "Natural Noise"
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Jebrail, F. F., and R. S. Kistler. L51753 Natural Draft Aerial Coolers. Pipeline Research Council International, Inc. (PRCI), 1996. http://dx.doi.org/10.55274/r0010422.
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In recent years, environmental regulations have tightened and community involvement in environmental issues has increased. The pipeline industry has responded by attempting to reduce the negative economic and environmental impact of conventional air-cooled heat exchangers, which are characterized by high noise levels, excessive energy consumption, and high maintenance costs. While industry has had limited success in reducing air cooler noise using silencers and timed variable-speed fans, these solutions are costly. The most effective noise reduction method is to reduce or eliminate noise at its source. The primary goals of this investigation were to address key technical issues and to document natural draft aerial cooler (NDAC) design knowledge. The following objectives were identified: - Form a project team from PRCI-recommended aerial cooler manufacturers to design a quiet aerial cooler - Conduct technical and economic analyses to determine the actual operating needs and constraints of NDACs - Conduct market analyses to evaluate and identify the marketing issues associated with NDACs - Document the results of the project in a final report In recent years, the number of environmental permits mandating the use of natural draft aerial coolers to reduce noise has increased. Natural draft aerial cooler technology can potentially eliminate noise and improve operational energy efficiency. A broad group of applications could benefit from this technology, including natural gas, engine jacket water, auxiliary water, and engine lube oil cooling. With noise regulations and penalties becoming increasingly stringent, natural draft heat transfer technology is becoming more important. No organization has as yet fully investigated it. The technical and economic feasibility of NDACs were investigated for natural gas, engine jacket water, auxiliary water, and lube oil cooler applications.
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Lamancusa. L51542 Noise Research and Projection Models for Natural Gas Facilities. Pipeline Research Council International, Inc. (PRCI), 1988. http://dx.doi.org/10.55274/r0010520.
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Covers research involving noise model requirements and evaluation of a number of existing models for applicability to pipeline compressor station conditions. Leads to development of improvements to existing AGASUM model. Resulting model, AGASOUND, is described and additional improvements still required are identified.
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Jay. L51710 Active Noise Silencing. Pipeline Research Council International, Inc. (PRCI), 1994. http://dx.doi.org/10.55274/r0010333.
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Many natural gas compressor stations which were previously located away from residential areas are now being encroached upon by surrounding building developments. Furthermore, an increased awareness of community noise issues has proved to be the impetus for investigating and developing more effective noise control methods and treatments for natural gas compressor facilities. This project investigates the feasibility of applying Active Noise Cancellation (ANC) to the exhaust of a large, internal-combustion reciprocating type engine. Large reciprocating internal combustion engines pose significant challenges for the noise control engineer. In the case of the engines employed at Tennessee Gas Pipeline Company Compressor Station 229, these engines radiate extremely low frequency exhaust noise into the surrounding environs. These engines produce discrete frequencies in the exhaust spectra with a particularly strong component at 26.5 Hz, which corresponds to the fundamental firing frequency (the 5.0 rotational order) of the engine; significant attenuation of the raw exhaust noise can be particularly difficult due to the sound power and spectral content. Traditional methods would necessitate a very large silencer in order to realize improved attenuation of the exhaust noise, relative to the existing silencer. Measurements were conducted at the error microphone location, at 1.0 meter from the exhaust outlet and at the property line. At a distance of 1.0 meter the WNCT integrated active / passive silencer yielded 84.5 dBA (92.3 dBL) while the original equipment silencer yielded 92.7 dBA (98.8 dBL). Band-limited (DC - 200 Hz) measurements were taken at the error microphone location; control off (WNCT passive - only): 109.8 dBL overall, 107.7 dBL 26.5 Hz component. With control on (WNCT active + passive) at the same position overall noise was 99.7 dBL with the 26.5 Hz component reading 89.1 dBL. Far-field A-weighted reductions were inconclusive due to the presence of other contributing noise sources possessing similar noise characteristics. Flow resistance measurements indicated that back pressure had been reduced by 95% relative to the original equipment silencer through the use of the integrated WNCT active / passive silencer.
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Meyer, Erik. Tule Springs Fossil Beds National Monument: Acoustic monitoring report 2019–2020. National Park Service, 2025. https://doi.org/10.36967/2309981.
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This study arose from a Tule Springs Fossil Beds National Monument (TUSK) technical assistance request titled “Soundscape Monitoring”, which identified the need for baseline acoustic surveys in the newly created park. Therefore, across one season in 2019, the Natural Sounds and Night Skies Division (NSNSD) gathered acoustical data at two sites in TUSK to provide park managers with information about the acoustical environment, sources of noise, and the natural and existing ambient sound levels within the park. On average, noise was present from 77 to 100 percent of the time across the two sites. The most common sources of noise were vehicles, aircraft, and unknown non-natural sounds. The maximum percent time audible for any detailed noise source were vehicles at site TUSK001, audible for 94% of a 24-hr period. Unknown non-natural noise was most audible at site TUSK002 (38%), followed by vehicles (37%). Overall, existing ambient sound levels (LA50) at sites within TUSK ranged from 27.3–31.9 dB during the day and 21.1–28.2 dB at night during the sampling period. Natural ambient sound levels (LAnat) at sites within TUSK ranged from 21.7–26.8 dB during the day and 18.1– 23.9 dB at night, although these measurements were likely influenced by the high prevalence of noise. In total, these results suggest that the TUSK acoustic environment is influenced by lower level, but very consistent noise. As a supplement, a geospatial sound model predicts existing and natural ambient sound levels at TUSK are 34.0 (dBA) and 21.4 (dBA), respectively.
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Branstetter, Brian K. Auditory Masking Patterns in Bottlenose Dolphins from Anthropogenic and Natural Noise Sources. Defense Technical Information Center, 2012. http://dx.doi.org/10.21236/ada573319.
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Branstetter, Brian K. Auditory Masking Patterns in Bottlenose Dolphins from Anthropogenic and Natural Noise Sources. Defense Technical Information Center, 2013. http://dx.doi.org/10.21236/ada598418.
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Spaulding, Arthur. The Natural and Man-made Noise Environment in Personal Communications Services Bands. Institute for Telecommunication Sciences, 1997. https://doi.org/10.70220/2sbmmw97.
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Meyer, Erik. Craters of the Moon National Monument and Preserve: Acoustic monitoring report, 2017. National Park Service, 2024. http://dx.doi.org/10.36967/2303262.
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This study arose from the Craters of the Moon National Monument and Preserve (CRMO) Resource Stewardship Strategy (RSS), which identified the need for baseline acoustic surveys in the park. Short-term natural soundscape RSS goals were to identify the condition of the acoustic resource, and the high priority stewardship activity associated with this goal was to collect baseline acoustic data. Therefore, from June?September 2017, the Natural Sounds and Night Skies Division (NSNSD) gathered acoustical data at six sites in CRMO to provide park managers with information about the acoustical environment, sources of noise, and the natural and existing ambient sound levels within the park. On average, noise was present from 7 to 85 percent of the time across the six sites. The most common sources of noise were vehicles, aircraft, and people. The maximum percent time audible for any detailed noise source was people at site CRMO004, audible for 81% of a 24-hr period. Aircraft was most audible at site CRMO005 (15%), and vehicles were most audible at site CRMO001 (20%). Overall, existing median ambient sound levels (LA50) at sites within CRMO ranged from 17.8?31.1 dB during the day and 15.6?34.0 dB at night during the sampling period. Natural ambient sound levels (LAnat) at sites within CRMO ranged from 16.4?30.0 dB during the day and 15.1?33.0 dB at night. The median impact, defined as the difference in dB between the LA50 and LAnat, was 1.4 dB. Noise impacts ranged from 1.1 dB at CRMO006 to 8.3 dB at CRMO004, where noise was audible for 100% of the time from 07:00 to 10:00.
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Olstad, Tyra. Sleeping Bear Dunes National Lakeshore: Acoustic monitoring report, 2022. National Park Service, 2025. https://doi.org/10.36967/2309412.
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This study was conducted in response to Technical Assistance Request (TAR) 20133, which identified a need for a baseline acoustic inventory within a discontinuous parcel of Sleeping Bear Dunes National Lakeshore (SLBE). Although the Bow Lakes parcel is frequented by visitors seeking a quiet refuge away from crowds, it is bordered by three privately owned and operated sand and gravel mines. The park needs information about existing and natural ambient sound levels to evaluate the effects of mining noise on the parcel. In March-April 2022, the Natural Sounds and Night Skies Division (NSNSD) gathered acoustic data at two sites in the Bow Lakes parcel in SLBE, discontinuous from the popular areas along the shoreline as well as the Sleeping Bear Dunes Wilderness but bordered by three privately owned and operated sand and gravel mines. On average, noise was present 71.2–77.3% of the time at these sites, with vehicles the most common identifiable source of non-natural noise, audible an average of 22.9–23.2% of the time, and heavy equipment the main contributor. Existing median ambient sound levels (LA50) ranged from 24.1–24.2 dB at night and 30.2–30.9 dB during the day. Natural ambient sound levels (LAnat) ranged from 20.9 dB at night to 26.9–27.6 during the day. The median influence noise has on the acoustic environment, defined as the difference between LA50 and LAnat, was 3.2–3.3 dB, representing a detectable increase in sound levels due to anthropogenic noise. In the ANS-weighted frequency range, the sound level of 35 dB (LAeq, 1s), indicative of quiet environments, was exceeded 14.27–14.35% of the day and 7.36–10.49% of the night. All other key sound levels (i.e., 45 dB and above) were exceeded less than 0.4% of the time. To summarize, the Bow Lake parcel receives consistent but low-level anthropogenic noise that would be noticeable to a listener. A geospatial sound model designed to estimate sound levels over larger areas predicts existing median sound level (L50) of 37.0 dBA and a median natural L50 of 33.6 dBA across the park, with lower sound levels in the Wilderness Area and Bow Lakes parcel and localized effects from anthropogenic noise, especially along M-22.
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Meyer, Erik. Cabrillo National Monument: Acoustic monitoring report, 2021. National Park Service, 2024. http://dx.doi.org/10.36967/2303446.
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This study arose from the Cabrillo National Monument (CABR) Resource Stewardship Strategy (RSS), which identified the need for baseline acoustic surveys in the park. One of the RSS stewardship goals was to minimize anthropogenic sounds outside and inside park boundaries to enhance the visitor experience. A Technical Assistance Request (TAR) for natural sounds inventory was submitted to the Natural Sounds and Night Skies Division. Therefore, in May 2021, the NSNSD gathered acoustic data at two sites in CABR to provide park managers with information about the acoustic environment, sources of noise, and the existing ambient sound levels within the park. On average, noise was present from 95 to 99 percent of the time across the two sites. The most common sources of noise were aircraft, motor sounds, and a foghorn. The maximum percent time audible for any detailed noise source was the foghorn at site CABR001, audible for 95% of a 24-hr period over 10 days of listening. Motor sounds were most audible at site CABR002, audible for 68% of the time. Overall, existing ambient sound levels (LA50) at sites at CABR were 39.5 and 43.1 dB during the day and 34.7 and 42.5 dB at night during the sampling period (CABR001 and CABR002, respectively). Natural ambient sound levels (LAnat) were 30.2 and 38.0 dB during the day and 26.6 and 38.4 dB at night for CABR001 and CABR002 respectively, although these measurements were likely influenced by the high prevalence of noise. As a supplement, a geospatial sound model predicts existing and natural ambient sound levels at CABR are 46.0 (dBA) and 31.4 (dBA), respectively.