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Showing papers on "Noise pollution published in 1998"


Journal ArticleDOI
12 Oct 1998
TL;DR: The study summarizes the emerging future directions in noise mitigation studies and points the reader to relevant research in the past on noise identification and mitigation techniques.
Abstract: Increasing awareness of industrial noise pollution and emerging stricter standards have made noise an important topic of research in electric machines. This work is a state-of-the-art review on the identification of noise sources and techniques to mitigate noise. It points the reader to relevant research in the past on acoustic noise identification and mitigation techniques. The paper also describes the current standards and practices and some of the suggestions in literature to intensify these standards. The paper summarizes the emerging future directions in acoustic noise mitigation studies.

196 citations


Proceedings ArticleDOI
12 May 1998
TL;DR: This paper shows how hidden Markov models (HMMs) can be used to build an environmental noise recognition system based on a time-frequency analysis of the noise signal.
Abstract: The automatic classification of environmental noise sources from their acoustic signatures recorded at the microphone of a noise monitoring system (NMS) is an active subject of research nowadays. This paper shows how hidden Markov models (HMMs) can be used to build an environmental noise recognition system based on a time-frequency analysis of the noise signal. The performance of the proposed HMM-based approach is evaluated experimentally for the classification of five types of noise events (car, truck, moped, aircraft, train). The HMM-based approach is found to outperform previously proposed classifiers based on the average spectrum of the noise event with more than 95% of correct classifications. For comparison, a classification test is performed with human listeners for the same data which shows that the best HMM-based classifier outperforms the "average" human listener who achieves only 91.8% of correct classification for the same task.

75 citations


Journal ArticleDOI
TL;DR: Noise sources and levels were evaluated in an intensive care unit (ICU) in Athens, Greece and staff awareness and sensitivity are needed to counteract noise pollution in ICUs.
Abstract: Noise sources and levels were evaluated in a six-bed intensive care unit (ICU) in Athens, Greece Ten patients (six males, four females) completed specifically designed questionnaires, and at the same time nine 8-h sound measuring sessions took place A Bruel and Kjaer 2231 sound-meter was used on the decibel-A scale combined with observation Human activity, operating equipment and construction engineering of the hospital building were identified as sources of noise Noise levels were elevated [LEQ=603–674 dB(A)] No reliable information was obtained from the questionnaires ICU noise levels were higher by 27 dB(A) than recommended hospitals levels To counteract noise pollution in ICUs, staff awareness and sensitivity are needed

69 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present an analysis of the adoption and implementation of Chinese environmental policies and pollution abatement measures, which could be legal, administrative or economic, are analysed both as part of more general programmes of legal and economic reform, and as specific designs for local or sectoral problems.
Abstract: This paper presents an analysis of the adoption and implementation of Chinese environmental policies and pollution abatement measures. It sketches the role of the State Environmental Protection Administration (SEPA) and the recently adopted Five-Year Plan for the years 1996–2000 in coping with China's increasing problems of water, air and soil pollution. Remedial measures, which could be legal, administrative or economic, are analysed both as part of more general programmes of legal and economic reform, and as specific designs for local or sectoral problems. In previous articles, I have discussed several major environmental concerns: environmental damages, scarcity of water, control over emissions by township and village enterprises (TVEs), investments and management methods. The present contribution will focus on wider political issues, such as participatory policies, differences in implementation between regions and sectors, and most recent developments in industrial pollution problems and abatement measures. This survey cannot be complete: the limitations of space and the need to give some concrete examples make it necessary to be selective. Therefore, while some problems will be highlighted – such as water treatment in the Huai River basin, sulphur dioxide emissions, and pollution by TVEs – other problems such as noise pollution will be omitted.

67 citations


Journal ArticleDOI
TL;DR: In this article, direct reanalyses of over 57,000 interview responses to 35 noise sources in 20 social surveys and reviews of publications for over 12,000 additional responses to 16 noise sources and 13 social surveys show that residents' reactions to an audible environmental noise (a target noise) are only slightly or not at all reduced by the presence of another noise source (ambient noise) in residential environments.
Abstract: Direct reanalyses of over 57 000 interview responses to 35 noise sources in 20 social surveys and reviews of publications for over 12 000 additional responses to 16 noise sources in 13 social surveys show that residents’ reactions to an audible environmental noise (a target noise) are only slightly or not at all reduced by the presence of another noise source (ambient noise) in residential environments. The direct reanalyses account for type of noise source (aircraft, road traffic, railway, impulse noise), type of noise reaction question, type of activity disturbance, quality of noise data, type of regression analysis model (linear, logit, probit), two noise metrics (DNL, LAeq), and ten personal characteristics. Although there is considerable variation from survey to survey, the best direct estimate is that approximately a 20-dB increase in ambient noise exposure (95% confidence interval of 15–50 dB) has no more impact than approximately a 1-dB decrease in target noise exposure. Tabulations of 12 findings...

64 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured masked hearing thresholds of a beluga whale at the Vancouver Aquarium and found that the masked signal was a typical beluga vocalization; the masking noise included two types of icebreaker noise and naturally occurring icecracking noise.
Abstract: An experiment is presented that measured masked hearing thresholds of a beluga whale at the Vancouver Aquarium. The masked signal was a typical beluga vocalization; the masking noise included two types of icebreaker noise and naturally occurring icecracking noise. Thresholds were measured behaviorally in a go/no-go paradigm. Results were that bubbler system noise exhibited the strongest masking effect with a critical noise-to-signal ratio of 15.4 dB. Propeller cavitation noise completely masked the vocalization for noise-to-signal ratios greater than 18.0 dB. Natural icecracking noise showed the least interference with a threshold at 29.0 dB. A psychophysical analysis indicated that the whale did not have a consistent decision bias.

61 citations


Journal ArticleDOI
01 Jan 1998
TL;DR: In this paper, a random PWM modulator is described and tuned within a prescribed band of switching frequencies to "smear" the voltage spectrum and the results of listening tests are presented to show that significant perceived noise reductions are possible for relatively low switching bandwidths with but small computational overheads in the PWM generation.
Abstract: Acoustic noise radiated by industrial motor drives driven by PWM power electronic controllers is becoming ever more objectionable on industrial sites. The authors investigate such noise and show that the noise spectrum is closely related to the spectrum of the voltage waveform formed by the power electronics so that it may be "controlled" by controlling this voltage waveform. The paper describes a random PWM modulator and shows how it may be tailored within a prescribed band of switching frequencies to "smear" the voltage spectrum. Measured spectra and the results of listening tests are presented to show that significant perceived noise reductions are possible for relatively low switching bandwidths with but small computational overheads in the PWM generation.

54 citations


Journal ArticleDOI
TL;DR: The type of tasks carried out by the laborers, the sources of noise from heavy equipment around which they work, and the manual equipment they use determine the noise levels to which such workers are exposed.
Abstract: This study, conducted in 1987 and 1988, has made it possible to quantify exposure to noise among heavy equipment operators, associated laborers, and crane operators. The average daily noise exposure was 84 to 99 dBA for heavy equipment, 90 dBA for the laborer, and 74 to 97 dBA for the crane operator. The main sources of noise to which heavy equipment operators are exposed are vehicle engines and the muffler exhaust system, usually located near the operator. The presence of insulated cabs such as those found on power shovels, backhoes, wheel loaders, and graders help reduce noise exposure. The type of tasks carried out by the laborers, the sources of noise from heavy equipment around which they work, and the manual equipment they use determine the noise levels to which such workers are exposed. In the case of crane operators, an insulated cab significantly reduces the operator's exposure to engine noise.

43 citations


Journal ArticleDOI
TL;DR: A closed loop control system is designed which influences the green duration of the lights according to the equivalent noise level, which decreases the noise levels at intensive traffic intersections.
Abstract: An optimal control problem of traffic light duration is considered. The traffic noise level is introduced as a state variable in a dynamical optimization problem. A closed loop control system is designed which influences the green duration of the lights according to the equivalent noise level. Real time considerations lead to sub-optimal control implementation. This control policy decreases the noise levels at intensive traffic intersections. The traffic lights adapt their duration according to the noise pollution. Simulation and experimental results are discussed.

40 citations


Book
01 Jan 1998
TL;DR: Schafer as discussed by the authors addresses the problem of noise pollution and suggests solutions for it and stresses the importance of quiet and attempts to foster an increased sensitivity to the sound environment, and details the relationship of the private and the public in this issue.
Abstract: A primer that, in simple language, addresses the problem of noise pollution and suggests solutions for it. In opposition to a vulgar culture that celebrates its own noise, Schafer stresses the importance of quiet and attempts to foster an increased sensitivity to the sound environment. He details the relationship of the private and the public in this issue, and lists organisations for concerned citizens to contact. Bibl. 1 p.

35 citations


Journal ArticleDOI
TL;DR: In this article, acoustic shields are used to isolate the side lobe energy of the transmitted acoustic pulse, which is effective in blocking out active ambient background noise in sodar applications, but they are not suitable for outdoor applications.

Journal ArticleDOI
TL;DR: In this article, the results of the noise emitted by machines are analyzed to predict an overall noise climate, and the results show that the noise levels in coal washeries, coal preparation plants, open cast and underground mining centres are very high when compared to accepted limits for occupational noise exposure.

Journal ArticleDOI
TL;DR: In this paper, an acoustical environment survey was carried out in six similar air conditioned landscaped offices in which human speech was considered to be the major source of complaint and both questionnaire and physical noise measurement were administrated.

Journal ArticleDOI
TL;DR: In this paper, a linear regression model has been fitted to predict the noise levels for Delhi, based on observations and taking into account the specific site characteristics, and it is found that noise levels are primarily determined by vehicular traffic.
Abstract: Noise levels have been measured at several sites spread throughout Delhi. Based on these observations and taking into account the specific site characteristics, a linear regression model has been fitted to predict the noise levels for Delhi. It is found that noise levels are primarily determined by vehicular traffic. The residential areas have considerably lower noise levels than commercial areas. The results indicate that the vegetation has a role in attenuation of noise levels.

Journal ArticleDOI
TL;DR: It was found that the numbers currently in use by industry for clutter loss are, in general, slightly less than the observed values.
Abstract: To enhance the accuracy of propagation predictions for broadcasting and land mobile applications, a more accurate characterization of clutter loss and of environmental noise has been needed. A series of tests was performed to quantify the environmental RF noise levels associated with various types of ground clutter and to quantify the effects of ground clutter on RF propagation path loss. Tests were performed at 162, 460, and 860 MHz in four different localities in the United States. Each had very different land clutter, as characterized by the land use land cover (LULC) categories used in the United States. It was found that the numbers currently in use by industry for clutter loss are, in general, slightly less than the observed values. Both the clutter loss and noise results can be applied to system design.

Proceedings ArticleDOI
C. Teoh, K. Soh, R. Zhou, D. Tien, V. Chan 
03 Mar 1998
TL;DR: In this paper simulation results are presented, the nature of the problem is analyzed mathematically and the weakness of the commonly used methods are exposed and the mathematics of an improved fast algorithm is given.
Abstract: Acoustic noise generated by transformers is a serious form of environmental pollution and it affects people's lives. Different methods have been suggested to reduce this form of pollution. This paper describes the implementation of a DSP based active noise control (ANC) system. Based on the theoretical result, different noise control systems were built and studied during this project. Results collected from the noise cancellation testing showed that a noise reduction level of 5 to 15 dB can be achieved. In this paper simulation results are presented, the nature of the problem is analyzed mathematically and the weakness of the commonly used methods are exposed. Finally, the mathematics of an improved fast algorithm is given.

01 Oct 1998
TL;DR: In this article, noise comfort is considered, with special emphasis on the developing criteria for low-frequency noise in HVAC environments, including thermal, lighting, and air cleanliness conditions.
Abstract: Typical HVAC noise may produce an uncomfortable environment, leading to the associated problems of general dissatisfaction and reduced productivity. It is not sufficient to have good thermal, lighting, and air cleanliness conditions if the noise is disturbing. In this paper, noise comfort is considered, with special emphasis on the developing criteria for low-frequency noise.


Journal Article
TL;DR: An objective assessment of the effect of ANR on noise levels at the tympanic membrane is provided to provide advice on what factors should be taken into account when ANR is evaluated for use in an aviation operational environment.
Abstract: Background Active noise reduction (ANR) is an electronic system that works by continuous sampling of noise inside the earshell of the headset with a small microphone. This signal is inverted in phase through the headset speaker, thus reducing noise levels by destructive interference of the acoustic field. The system provides good low-frequency noise attenuation, but aircrew differ in their subjective opinion of ANR. The present study is an attempt to provide an objective assessment of the effect of ANR on noise levels at the tympanic membrane. Methods There were 7 subjects with normal ears who were placed in an environment of recorded noise from a BO-105 helicopter. A microphone probe was inserted to within 5 mm of the tympanic membrane of each subject's right ear. Noise levels in the ear were measured without a headset and with two different ANR headsets. Measurements were performed with and without the ANR system on, and with and without white noise through the headset communication system. The white noise was used to simulate aircraft communication noise. Results The two headsets tested had differing levels of passive and active attenuation. The ANR system produced a substantial low-frequency attenuation. However, noise levels in the mid frequencies increased somewhat when the ANR system was switched on. This effect was augmented when white noise in the communications system was introduced, particularly for one of the two headsets. Low-frequency noise attenuation of ANR systems is substantial, but an increased mid- and high-frequency noise level caused by the ANR may affect both communication and overall noise levels. Our data provide advice on what factors should be taken into account when ANR is evaluated for use in an aviation operational environment.

Journal ArticleDOI
TL;DR: In this article, a study has shown that train noise has distinct vertical directivity pattern and as the angle of elevation increases from 10° to 30°, the train noise increases by about 7dB(A) which is clearly perceptible.

Journal ArticleDOI
01 Oct 1998
TL;DR: In this article, the authors developed a 3D model to determine the maximum allowable noise exposure time for multiple uncorrelated sources in a plant layout and also took into account the acoustic characteristics of materials used in constructing the room.
Abstract: The primary objective of this study is to develop a 3D model to determine the maximum allowable noise exposure time. This model allows the presence of multiple uncorrelated sources. The model provides an optimal arrangement for locating various machinery and equipment in the plant layout and also takes into consideration the acoustic characteristics of materials used in constructing the room. A detailed description of the models and results obtained will be presented and discussed.

01 Apr 1998
TL;DR: It was found that all computer-based airport monitoring systems provide at least rudimentary tools for performing data base searches by complainant name, address, date, time of day, and types of aircraft and complaints.
Abstract: This study assessed the feasibility of using complaint information archived by modem airport monitoring systems to conduct quantitative analyses of the causes of aircraft noise complaints and their relationship to noise- induced annoyance. It was found that all computer-based airport monitoring systems provide at least rudimentary tools for performing data base searches by complainant name, address, date, time of day, and types of aircraft and complaints. Analyses of such information can provide useful information about longstanding concerns, such as the extent to which complaint rates are driven by objectively measurable aspects of aircraft operations; the degree to which changes in complaint rates can be predicted prior to implementation of noise mitigation measures; and the degree to which aircraft complaint information can be used to simplify and otherwise improve prediction of the prevalence of noise-induced annoyance in communities.

ReportDOI
01 Nov 1998
TL;DR: The features of the NOISEMAP (NMAP) 7.0 computer program are described and the relationship of these primary programs to the other secondary programs, as well as the conceptual flow of data are shown.
Abstract: : NMAP 7.0 is the most current version of the Department of Defense (DOD) computer program suite for the modeling of aircraft noise from aircraft flight and static events at an airbase. This report describes the features of the NOISEMAP (NMAP) 7.0 computer program and its operation. The entire suite encompassed by NMAP 7.0 includes several different programs. The three primary IBM-compatible PC-based programs in the suite are BASEOPS 7.0, NMAP 7.0, and NMPLOT 4.2. The report shows the relationship of these primary programs to the other secondary programs, as well as the conceptual flow of data. BASEOPS is used to enter all aircraft operational data including number of flight and static events, flight and static profiles, flight tracks, etc. NMAP is the computational module. This module accepts the data entered in the BASEOPS program, and estimates noise levels caused by aircraft events at many points on the ground in the airbase vicinity. NMPLOT is used to draw lines of equal noise level (noise contours) to determine the overall noise exposure and related environmental impacts (from aircraft and other sources).


ReportDOI
01 Sep 1998
TL;DR: In this article, a low cost muzzle blast muffler was used to reduce small arms noise impact in the neighborhood of Camp Dodge, IA, and the performance tests showed that the muffler delivered a noise level reduction in the A weighted sound exposure level (ASEL) of 10 to 20 decibels (dB) in most of the noise sensitive regions around Camp Dodge.
Abstract: : Small arms fire can result in noise complaints from nearby residents The objective of the project reported herein was to provide a mitigation strategy to reduce small arms noise impact in the neighborhood of Camp Dodge, IA The selected strategy was a low cost muzzle blast muffler The US Army Construction Engineering Research Laboratories (USACERL) designed, constructed, and tested several variations of mufflers The basic design consists of a tube about 05 meter (19 inches) in diameter and about 19 meters (6 feet) long that is lined with noise absorbent material and has a bore large enough to afford the shooter an unobstructed view of the target The performance tests showed that the muffler delivers a noise level reduction in the A weighted sound exposure level (ASEL) of 10 to 20 decibels (dB) in most of the noise sensitive regions around Camp Dodge


Journal ArticleDOI
TL;DR: Proponent mitigated development (PMD) strategies are used in the planning stages of new development to bring about compatibility between noise sensitive land uses and transportation noise as mentioned in this paper, which is an effective complement to land use zoning in traffic noise and land use compatibility programs.
Abstract: Proponent mitigated development (PMD) strategies are used in the planning stages of new development to bring about compatibility between noise sensitive land uses and transportation noise. Development can be a transportation project initiated by a transportation agency or it can be a noise sensitive land use initiated by a private developer. In either case, the proponent of the development bears the responsibility for mitigation of transportation noise to bring about noise and land use compatibility. Noise and land use compatibility programs that make use of proponent mitigated development strategies were studied to identify critical program elements, measures of effectiveness, and the steps to be taken for program implementation. It was found that proponent mitigated development strategies can be an effective complement to land use zoning in traffic noise and land use compatibility programs. Further, administrators of existing programs report minimal maintenance costs to planning agencies, and suggest th...

ReportDOI
01 Feb 1998
TL;DR: In this paper, the authors developed an algorithm to simulate this penetrating sonic boom noise for realistically shaped sonic booms, predictions previously unavailable, assuming that the water surface is fairly flat and the water is deep enough so that bottom reflections can be ignored.
Abstract: : Sonic boom noise from overwater supersonic aircraft operations penetrates into the water. The present work developed an algorithm to simulate this penetrating sonic boom noise for realistically shaped sonic booms, predictions previously unavailable. The new algorithm assumes that the water surface is fairly flat and that the water is deep enough so that bottom reflections can be ignored. The algorithm was used to model the underwater sonic boom noise for the cases of incident sonic boom waves distorted by atmospheric effects and by common aircraft maneuvers. It was found that certain aircraft maneuvers and atmospheric effects can increase the penetration of the sonic boom noise, while others decrease it.

Journal ArticleDOI
TL;DR: Three alternative models of traffic noise prediction have been applied to two major roads in a large provincial city in Australia and the sensitivity of the environmental capacity to changes in setback distance, traffic composition, traffic speed, and acceptable noise levels is explored.
Abstract: Three alternative models of traffic noise prediction have been applied to two major roads in a large provincial city in Australia. The roads are segmented into links and the environmental capacity of each link is determined. Both one-hour and 18-hour noise levels are used for capacity estimation. This allows a rational comparison of the ease of use, data requirements as well as limitations of alternative traffic noise models. The sensitivity of the environmental capacity to changes in setback distance, traffic composition, traffic speed, and acceptable noise levels is explored. This is useful in the formulation of rational strategies for improving the environmental capacities of roads. The amelioration models should, wherever possible, allow the environmental capacity to be as close as is practical to the physical capacity at level of service E An opinion survey of the residents in the study area has been conducted with a view to determining acceptable noise levels. Based on these studies, noise levels for various land uses and times of day are recommended and estimates of environmental capacities of the two roads are presented

01 Jan 1998
TL;DR: In this article, the authors present the current knowledge on road traffic noise to planners and traffic and road engineers, and provide methods and means which are applicable for noise reduction in Denmark.
Abstract: Road traffic is the main cause of noise exposure in Denmark. Noise from road traffic is a problem in peoples' homes, in recreational areas and at facilities for pedestrian and bicycle traffic. The Danish Environmental Protection Agency's sound limit value in residential areas is 55 dB(A). This value is exceeded at just under half a million of the 2.4 million Danish residences. Since the early 1970s the EU has tightened the limitations on vehicle noise emission by approximately 10 dB. Unfortunately extensive Nordic noise measurements have shown that the actual reductions due to the tightened limitations are only a little more than 1 dB. Therefore improved vehicle technology cannot stand alone as a solution to the problem of noise from road traffic. This textbook is intended to present the current knowledge on road traffic noise to planners and traffic and road engineers. The book consists of a theoretical part on basic acoustics, nuisance and legislation, and a practical part on noise estimation and mapping, means of mitigation and planning approaches for noise reduction. The book is concentrated on supplying methods and means which are applicable. Danish and international cases are used for exemplification.