The tire air cavity mode is known to be a significant source of vehicle structure-borne road noise near 200 Hz. A porous lining placed on the inner surface of a tire is an effective countermeasure to attenuate that resonance. The two noticeable effects of such a lining are the sound pressure attenuation and the frequency reduction of the air cavity mode. In this paper, through both analytical and numerical methods, the mechanism of the effects of porous lining was studied. A two-dimensional duct-shaped analytical model and a tire-shaped numerical model were built to investigate the lined tire in conjunction with the Johnson-Champoux-Allard model describing the visco-inertial dissipative effects of the porous material. Design parameters of the porous lining were controlled to study their impact and optimal ranges of the design parameters were suggested. Finally, in experimental analysis, the sound attenuation and the frequency drop were observed in measurements of force, acceleration, and sound pressure. In conclusion, it was demonstrated that the suggested analytical and numerical models successfully predict the effect of porous lining and that the frequency reduction results from the decreased sound speed within the tire owing to the presence of the liner.
{"title":"Frequency reduction and attenuation of the tire air cavity mode due to a porous lining","authors":"K. Choo, Wonhong Choi, Guochenhao Song, J. Bolton","doi":"10.3397/nc_2023_0012","DOIUrl":"https://doi.org/10.3397/nc_2023_0012","url":null,"abstract":"The tire air cavity mode is known to be a significant source of vehicle structure-borne road noise near 200 Hz. A porous lining placed on the inner surface of a tire is an effective countermeasure to attenuate that resonance. The two noticeable effects of such a lining are the sound\u0000 pressure attenuation and the frequency reduction of the air cavity mode. In this paper, through both analytical and numerical methods, the mechanism of the effects of porous lining was studied. A two-dimensional duct-shaped analytical model and a tire-shaped numerical model were built to investigate\u0000 the lined tire in conjunction with the Johnson-Champoux-Allard model describing the visco-inertial dissipative effects of the porous material. Design parameters of the porous lining were controlled to study their impact and optimal ranges of the design parameters were suggested. Finally, in\u0000 experimental analysis, the sound attenuation and the frequency drop were observed in measurements of force, acceleration, and sound pressure. In conclusion, it was demonstrated that the suggested analytical and numerical models successfully predict the effect of porous lining and that the\u0000 frequency reduction results from the decreased sound speed within the tire owing to the presence of the liner.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"137 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82259094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fused deposition modeling (FDM) is the most common and cost effective form of additive manufacturing (AM). Due to the ubiquity of the approach, a range of off the shelf composite materials have been developed by companies, often with the goal of improving the printed part's physical appearance or increasing or decreasing the weight of the part. These composites typically have a base material of a standard FDM printed polymer, with additives such as metal particulates or lightweight filler added. This study will examine the dynamic properties of a set of off the shelf materials to characterize acoustic sound speed, complex elastic moduli, and loss. All of the materials in this study have a base material of polylactic acid (PLA) making it possible to easily print them into multi-material structures. The filler materials showed minimal impact on some viscoelastic properties but resulted in significant changes in acoustic sound speed. Characterization of this type is a critical component in development of an expanded database of material properties for use in design.
{"title":"Dynamic characterization of off the shelf polymer composites printed with fused deposition modeling","authors":"Christina J. Naify, James Stephens, Aytahn Benavi","doi":"10.3397/nc_2023_0122","DOIUrl":"https://doi.org/10.3397/nc_2023_0122","url":null,"abstract":"Fused deposition modeling (FDM) is the most common and cost effective form of additive manufacturing (AM). Due to the ubiquity of the approach, a range of off the shelf composite materials have been developed by companies, often with the goal of improving the printed part's physical appearance or increasing or decreasing the weight of the part. These composites typically have a base material of a standard FDM printed polymer, with additives such as metal particulates or lightweight filler added. This study will examine the dynamic properties of a set of off the shelf materials to characterize acoustic sound speed, complex elastic moduli, and loss. All of the materials in this study have a base material of polylactic acid (PLA) making it possible to easily print them into multi-material structures. The filler materials showed minimal impact on some viscoelastic properties but resulted in significant changes in acoustic sound speed. Characterization of this type is a critical component in development of an expanded database of material properties for use in design.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"19 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89681020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crypto-currency mining facilities have become more and more common over the last few years, but there is no standard for construction or noise mitigation for these facilities. Many noise issues are encountered after the facilities are complete and operating. The facilities can contain thousands of "miners" which can be quite loud. Often, the manufacturers do not supply reliable sound data and the miners themselves are constantly evolving. The miners have extreme power and ventilation requirements which introduce additional noise sources and paths, as well as site requirements. I have examined the effectiveness of mitigation techniques for these facilities and addressed potential pitfalls for facilities based on similar issues observed across several projects.
{"title":"Common pitfalls and potential solutions for crypto-currency mining facility noise","authors":"Iliana Schad","doi":"10.3397/nc_2023_0049","DOIUrl":"https://doi.org/10.3397/nc_2023_0049","url":null,"abstract":"Crypto-currency mining facilities have become more and more common over the last few years, but there is no standard for construction or noise mitigation for these facilities. Many noise issues are encountered after the facilities are complete and operating. The facilities can contain\u0000 thousands of \"miners\" which can be quite loud. Often, the manufacturers do not supply reliable sound data and the miners themselves are constantly evolving. The miners have extreme power and ventilation requirements which introduce additional noise sources and paths, as well as site\u0000 requirements. I have examined the effectiveness of mitigation techniques for these facilities and addressed potential pitfalls for facilities based on similar issues observed across several projects.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"4 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79988821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic properties of hydraulic bushings are often modeled in the time and frequency domains with low-order, lumped-parameter models, typically assuming steady, developed flow in their fluid passages, whereas in situ flow conditions are unlikely to meet such criteria. Hydraulic bushings exhibit tuned properties emerging from nonlinear interactions involving these flow characteristics, so higher resolution descriptions of the underlying physics are needed under realistic flow conditions. This paper discusses an approach to isolate the fluid passage features in production bushings to enable experimental characterization for steady, oscillatory, and transient flow. More robust models of dynamic responses in the time and frequency domains are expected to result from this more precise determination of each flow path's contribution to the nonlinear system response. An apparatus capable of generating steady and dynamic flow is proposed, and some validation data is given to demonstrate the functionality of the experiment. Some challenges with the approach are considered, including the system's hydraulic compliance and cavitation. The flow testing apparatus is used on an example two-passage production bushing adapted for controlled steady or dynamic flow through one or both flow paths. Finally, some nonlinear flow properties of a typical hydraulic bushing's flow passages are given.
{"title":"Experimental dynamic flow characterization of hydraulic bushings","authors":"Kenneth DeGarmo, M. Kennedy, Luke Fredette","doi":"10.3397/nc_2023_0130","DOIUrl":"https://doi.org/10.3397/nc_2023_0130","url":null,"abstract":"The dynamic properties of hydraulic bushings are often modeled in the time and frequency domains with low-order, lumped-parameter models, typically assuming steady, developed flow in their fluid passages, whereas in situ flow conditions are unlikely to meet such criteria. Hydraulic\u0000 bushings exhibit tuned properties emerging from nonlinear interactions involving these flow characteristics, so higher resolution descriptions of the underlying physics are needed under realistic flow conditions. This paper discusses an approach to isolate the fluid passage features in production\u0000 bushings to enable experimental characterization for steady, oscillatory, and transient flow. More robust models of dynamic responses in the time and frequency domains are expected to result from this more precise determination of each flow path's contribution to the nonlinear system response.\u0000 An apparatus capable of generating steady and dynamic flow is proposed, and some validation data is given to demonstrate the functionality of the experiment. Some challenges with the approach are considered, including the system's hydraulic compliance and cavitation. The flow testing apparatus\u0000 is used on an example two-passage production bushing adapted for controlled steady or dynamic flow through one or both flow paths. Finally, some nonlinear flow properties of a typical hydraulic bushing's flow passages are given.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"32 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78934719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Esmeralda Sanchez-Torres, B. Sharma, D. Sutliff, Aikaterini Stylianides, Jake Puppo, Denver Schaffarzick, Michael Jones
Previous research shows that open-celled metal foam liners have the potential to provide substantial aircraft noise reduction benefits. Our recent results show that their normal incidence sound absorption performance can be further improved by compressing them uniformly; this compression reduces their effective pore size and increases the thermoviscous losses. Further, their performance may be optimized by stacking foams with varying degrees of compression and creating a step-wise effective relative density gradient. Here, we present the results from our recent experiments, evaluating the attenuation performance of such a step-wise gradient metal foam liner using the Advanced Noise Control Fan (ANCF). Liner spools with two different step-wise configurations were fabricated and tested using the ANCF test rig at the Notre Dame Turbomachinery Laboratory. Farfield data was gathered with the liner spool mounted at the inlet and aft locations. In this paper, we present our results comparing the attenuation performance under both test conditions as compared to measurements obtained using a hard wall baseline configuration. Our results show that step-wise metal foam configurations can provide robust acoustical performance for aircraft noise reduction applications.
{"title":"Evaluation of metal foam liners for broadband noise reduction of turbofan engines","authors":"Esmeralda Sanchez-Torres, B. Sharma, D. Sutliff, Aikaterini Stylianides, Jake Puppo, Denver Schaffarzick, Michael Jones","doi":"10.3397/nc_2023_0038","DOIUrl":"https://doi.org/10.3397/nc_2023_0038","url":null,"abstract":"Previous research shows that open-celled metal foam liners have the potential to provide substantial aircraft noise reduction benefits. Our recent results show that their normal incidence sound absorption performance can be further improved by compressing them uniformly; this compression\u0000 reduces their effective pore size and increases the thermoviscous losses. Further, their performance may be optimized by stacking foams with varying degrees of compression and creating a step-wise effective relative density gradient. Here, we present the results from our recent experiments,\u0000 evaluating the attenuation performance of such a step-wise gradient metal foam liner using the Advanced Noise Control Fan (ANCF). Liner spools with two different step-wise configurations were fabricated and tested using the ANCF test rig at the Notre Dame Turbomachinery Laboratory. Farfield\u0000 data was gathered with the liner spool mounted at the inlet and aft locations. In this paper, we present our results comparing the attenuation performance under both test conditions as compared to measurements obtained using a hard wall baseline configuration. Our results show that step-wise\u0000 metal foam configurations can provide robust acoustical performance for aircraft noise reduction applications.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"72 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79584496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A spacecraft cabin ventilation fan suitable for aerodynamic and acoustic ground tests was designed and two copies of the fan assembly were fabricated - designated as Quiet Space Fan. Both fans were tested for aerodynamic performance and acoustic levels in the NASA Glenn Research Center Acoustical Testing Laboratory. A new test rig for small axial flow fans was designed to accommodate the instrumentation and back-pressure adjustments. Measurements acquired were - static pressures for measuring performance, a 72-channel in-duct microphone array, external microphone measurements for acoustics, and inter-stage hot wire measurements of the fan wake. This report documents the acoustic measurements as part of a series of reports.
{"title":"Quiet Spacecraft Cabin Ventilation Fan: Acoustic Measurements Results","authors":"D. Sutliff","doi":"10.3397/nc_2023_0010","DOIUrl":"https://doi.org/10.3397/nc_2023_0010","url":null,"abstract":"A spacecraft cabin ventilation fan suitable for aerodynamic and acoustic ground tests was designed and two copies of the fan assembly were fabricated - designated as Quiet Space Fan. Both fans were tested for aerodynamic performance and acoustic levels in the NASA Glenn Research Center\u0000 Acoustical Testing Laboratory. A new test rig for small axial flow fans was designed to accommodate the instrumentation and back-pressure adjustments. Measurements acquired were - static pressures for measuring performance, a 72-channel in-duct microphone array, external microphone measurements\u0000 for acoustics, and inter-stage hot wire measurements of the fan wake. This report documents the acoustic measurements as part of a series of reports.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"56 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91091980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although Burbank, California has long been touted as the "Media Capital of the World", there is certainly an argument to be made that New York City is the true Media hub. Broadcasting companies are expanding their footprint building new studios, and non-media companies are expanding to include in-house broadcasting capabilities. Unfortunately, while broadcast studios, recording booths, and production spaces typically require very low noise levels, New York City is also known for its boisterous hustle and bustle. We will review a case study involving Live Broadcast Studios and product spaces being constructed at a sub-cellar level adjacent to the New York City MTA Subway tunnel. Several studies were conducted prior to construction to determine the appropriate whole building and structural isolation measures for the project. Simulations were then used to demonstrate expected noise levels to the client to inform decision making. Given the project cost and expectations, additional measurements are being taken through construction to confirm and track reduced vibration and noise levels.
{"title":"Structural and architectural isolation methods for incompatible programming adjacencies","authors":"Caitlin I. Ormsbee","doi":"10.3397/nc_2023_0087","DOIUrl":"https://doi.org/10.3397/nc_2023_0087","url":null,"abstract":"Although Burbank, California has long been touted as the \"Media Capital of the World\", there is certainly an argument to be made that New York City is the true Media hub. Broadcasting companies are expanding their footprint building new studios, and non-media companies are\u0000 expanding to include in-house broadcasting capabilities. Unfortunately, while broadcast studios, recording booths, and production spaces typically require very low noise levels, New York City is also known for its boisterous hustle and bustle. We will review a case study involving Live Broadcast\u0000 Studios and product spaces being constructed at a sub-cellar level adjacent to the New York City MTA Subway tunnel. Several studies were conducted prior to construction to determine the appropriate whole building and structural isolation measures for the project. Simulations were then used\u0000 to demonstrate expected noise levels to the client to inform decision making. Given the project cost and expectations, additional measurements are being taken through construction to confirm and track reduced vibration and noise levels.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"35 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82646613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An inverse method is used to characterize radiating noise sources. Measurements of the sound pressure in the field are used to reconstruct the vibration on the surface of a vibrating structure. The basis functions for this inverse calculation are pellicular modes. These modes are calculated by assuming that there is a thin air envelope around the vibrating structure. The acoustic modes are calculated using this air envelope and the acoustic mode shapes are then assumed to be structural modes. Though not the actual structural modes, these modes are easily calculated and form convenient basis functions. This procedure is demonstrated on two examples. The first is a small electric motor and the second is a generator set. It is demonstrated that the procedure can be used to accurately characterize the sound radiation from a source.
{"title":"Source Characterization using Inverse Numerical Acoustics based on Pellicular Modes","authors":"Xin Yan, D. Herrin, Nikhil Ghaisas","doi":"10.3397/nc_2023_0054","DOIUrl":"https://doi.org/10.3397/nc_2023_0054","url":null,"abstract":"An inverse method is used to characterize radiating noise sources. Measurements of the sound pressure in the field are used to reconstruct the vibration on the surface of a vibrating structure. The basis functions for this inverse calculation are pellicular modes. These modes are calculated\u0000 by assuming that there is a thin air envelope around the vibrating structure. The acoustic modes are calculated using this air envelope and the acoustic mode shapes are then assumed to be structural modes. Though not the actual structural modes, these modes are easily calculated and form convenient\u0000 basis functions. This procedure is demonstrated on two examples. The first is a small electric motor and the second is a generator set. It is demonstrated that the procedure can be used to accurately characterize the sound radiation from a source.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"43 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89237453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent advances in developing new tools and miniaturised devices to measure, analyse, model and simulate existing or future projects are more and more influencing the way to investigate and solve problems of various disciplines fostering deep changes in the research paradigms toward human-centred, multisensory and multidisciplinary approaches. In acoustics, beyond the negative effect of noise on individuals and its mitigation, researchers are even more interested in investigating how the complexity of the multisensory environment modulates the individuals' holistic experience. To this aim, the Department of the Università degli Studi della Campania "Luigi Vanvitelli" has built the Sens i-Lab, a key facility integrating, in a single test room, the simulation and control of the physical environment (acoustics, vision, lighting, microclimate, IAQ) with advanced systems for simulation of virtual environments. To complement the simulation and control of the stimuli, the Sens i-Lab is equipped with a set of systems and devices for motion tracking, for the measurement of the biofeedback signals (EEG, EDA, HRV, VAF) and their association with environmental stimuli and self-reported psychological measures of people well-being. Taking advantage of the Sens i-Lab setting, new research fields and applications in acoustics are possible. Some of them are presented.
{"title":"Sens i-Lab: a key facility to expand the traditional approaches in experimental acoustics","authors":"L. Maffei, M. Masullo","doi":"10.3397/nc_2023_0019","DOIUrl":"https://doi.org/10.3397/nc_2023_0019","url":null,"abstract":"Recent advances in developing new tools and miniaturised devices to measure, analyse, model and simulate existing or future projects are more and more influencing the way to investigate and solve problems of various disciplines fostering deep changes in the research paradigms toward\u0000 human-centred, multisensory and multidisciplinary approaches. In acoustics, beyond the negative effect of noise on individuals and its mitigation, researchers are even more interested in investigating how the complexity of the multisensory environment modulates the individuals' holistic experience.\u0000 To this aim, the Department of the Università degli Studi della Campania \"Luigi Vanvitelli\" has built the Sens i-Lab, a key facility integrating, in a single test room, the simulation and control of the physical environment (acoustics, vision, lighting, microclimate, IAQ)\u0000 with advanced systems for simulation of virtual environments. To complement the simulation and control of the stimuli, the Sens i-Lab is equipped with a set of systems and devices for motion tracking, for the measurement of the biofeedback signals (EEG, EDA, HRV, VAF) and their association\u0000 with environmental stimuli and self-reported psychological measures of people well-being. Taking advantage of the Sens i-Lab setting, new research fields and applications in acoustics are possible. Some of them are presented.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"21 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80919769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Noise walls are installed along highways to reduce highway traffic noise in adjacent communities. Based on installation or aging effects, some noise walls contain small gaps between panels. Applying traditional barrier insertion loss measurements comparing sections with and without gaps may not be possible due to site conditions. For this study, barrier-adjacent sound levels were collected at gap locations and comparable reference (non-gap) locations to determine the gap effect immediately behind the barrier. Two methods are then applied to determine how these gap effects translate to nearby communities. Both broadband and spectral sound levels are analyzed to determine that the effects of a small gap (up to 0.5 inches in height and 10 inches in length) can be up to 2 dB near the barrier but diminish rapidly with distance.
{"title":"Using barrier-adjacent measurements and predictions to determine effects of small gaps in highway noise wall","authors":"Colin Bliss, J. Rochat","doi":"10.3397/nc_2023_0166","DOIUrl":"https://doi.org/10.3397/nc_2023_0166","url":null,"abstract":"Noise walls are installed along highways to reduce highway traffic noise in adjacent communities. Based on installation or aging effects, some noise walls contain small gaps between panels. Applying traditional barrier insertion loss measurements comparing sections with and without\u0000 gaps may not be possible due to site conditions. For this study, barrier-adjacent sound levels were collected at gap locations and comparable reference (non-gap) locations to determine the gap effect immediately behind the barrier. Two methods are then applied to determine how these gap effects\u0000 translate to nearby communities. Both broadband and spectral sound levels are analyzed to determine that the effects of a small gap (up to 0.5 inches in height and 10 inches in length) can be up to 2 dB near the barrier but diminish rapidly with distance.","PeriodicalId":19195,"journal":{"name":"Noise & Health","volume":"85 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84320789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：