Showing papers on "Noise pollution published in 1997"

Status of road traffic noise in Calcutta metropolis, India

Abstract: Road traffic noise was measured at 24 traffic junctions of Calcutta, India during the summer of 1993, with the simultaneous recording of the number of vehicles passing. The A-weighted values of Leq(24), Ldn, L10, L90, L99, Lnp and TNI were determined. Statistical regression equations of Leq(h) were developed as a function of logarithm of the equivalent number of light/heavy vehicles per hour for the entire city and for zones within the city.

Effects of combined exposure to noise and toxic substances : Critical review of the literature

Abstract: A number of studies have been conducted in recent years investigating the potential effects on various health endpoints of the combination of noise and a variety of different industrial substances. This review indicates that the information available in both animals and humans on this subject is limited particularly with respect to assessing occupational risk. Most studies have focused on auditory effects in animals, although investigations have been performed for other toxicological endpoints. For some substances, notably toluene, the information from animals studies does suggest an interaction but these were performed only at exposure levels to both noise and chemicals which were each individually ototoxic. Single simultaneous exposure to noise and styrene did not result in any enhancement of auditory impairment above that produced by noise or styrene alone. Single simultaneous exposure to noise and carbon monoxide (CO), however, showed some evidence of enhancement of ototoxicity beyond that produced by noise or carbon monoxide alone, although only at high atmospheric concentrations of CO. When 1,3-dinitrobenzene was administered parentally at neurotoxic dose levels with continuous noise exposure, there was an increased severity of effects in the brain stem. Combined exposure to noise and lead and/or cadmium resulted in histopathological heart lesions of undefined severity, a finding which was not observed for either of those agents in isolation. Dermal exposure to dimethylformamide and noise or inhalation exposure to xylene and noise resulted in some biochemical changes in cardiac muscle which were of doubtful toxicological significance. In developing mice, there was evidence that combined exposure to cadmium sulphate and noise caused an increased incidence of external and skeletal malformations but only at dose levels of cadmium which would have induced developmental effects. Overall, for each of these chemicals and endpoints observed there is a suggestion of some interaction with noise exposure. From the data that are currently available, however, inferences cannot be drawn on whether or not interactions would have occurred at lower, more occupationally relevant, levels of exposure. A number of studies have investigated human populations exposed to both noise and industrial chemicals. Due to confounding factors, however, it was concluded that these data were inadequate for assessing the combined effects of noise and chemical exposure on hearing.

Performance of noise indices in air-conditioned landscaped office buildings

Abstract: Noise measurements and a questionnaire survey were carried out in air-conditioned landscaped offices in the present study in an attempt to find out what existing noise index gives the best correlation with the auditory sensation feeling of office workers. Results from statistical analyses show that the Equivalent Sound Pressure Level is the best among the 14 commonly used noise indices for this purpose. It is also found that the less commonly used Zwicker’s loudness level performs better than the commonly adopted Noise Criterion curves and Noise Rating curves in predicting auditory sensation of office workers in air-conditioned landscaped offices. The performance of the 14 noise indices in predicting auditory comfort are compared.

Environmental noise reduction based on speech/non-speech identification for hearing aids

Abstract: We proposed a very practical and useful noise reduction system that has wide application for hearing impaired persons, such as a sound-gathering system at a lecture hall or conference room. The system uses two basic technologies, a speech/non-speech identification process and a new noise reduction process. A speech/non-speech identification process uses four characteristics of the time and frequency domains of the input signal. In the noise reduction process, frequency weighting function is used for basic spectral subtraction and a loss control algorithm. Various kinds of environmental noise were reduced by this system, which showed excellent performance. Noise is further reduced by using a multi-microphone system as an acoustic noise suppressor. The results of intelligibility tests using persons with hearing loss show excellent noise reduction.

Interrupted traffic noise

Abstract: A one-parameter model (ξ) for stop-and-go noise is developed. The physics of the phenomenon is based on the idea of the linear density of radiated energy. The methodology of ξ determination has been worked out and illustrated. The noise interaction with the surface of the ground is considered to be the only wave phenomenon that disturbs geometrical spreading. The model makes possible the calculation of the correction term in the time-average sound level, LAT, as an adjustment to the constant speed model of traffic noise.

Noise assessment in LCA - a methodology attempt: A case study with various means of transportation on a set trip

Abstract: The present work focuses on impact assessment of noise disturbance in the framework of LCA studies.

Noise and its effects on people : An overview

Abstract: Excessive noise has a variety of effects on people. If sufficiently loud, it can cause temporary or permanent hearing loss. There is also some evidence that it may play a part in the development of heart disease. Noise interferes with our ability to communicate and to hear warning signals, and there is a great deal of evidence to show that noise interferes with our ability both to carry out and to learn complex cognitive tasks. This article reviews some of these effects, and draw attention to the areas of concern the of the major body concerned with the effects of noise on living organisms, the International Commission on the Biological Effects of Noise (ICBEN).

GAs for fuzzy modeling of noise pollution

Abstract: A growing problem in town areas is noise pollution due to the increasing number of vehicles that daily cross cities. A classical approach to model this kind of system is based on numerical regression, but its performance is not satisfactory due to the nonlinearity of the considered model. A suitable approach can be therefore to determine a fuzzy model of the system. There has been a considerable number of studies on fuzzy identification, where fuzzy implications are used to express rules, in this paper the Tagaki-Sugeno approach has been adopted applying a genetic algorithm during the optimization phase. The obtained models are compared with traditional ones showing the suitability of the proposed method.

Sound Intensity Prediction System (SIPS): Volume I - Reference Manual

Abstract: : The Sound Intensity Prediction System (SIPS) is a tool employed to reduce the number of complaints about noise from explosive operations. SIPS combines procedures for conducting explosive operations with an acoustic ray tracing computer code to determine the locations of both noise enhancements and noise reductions. By predicting areas that can expect either increased or decreased noise levels, noise levels in sensitive areas can be determined. Predictions of quiet zones covering those areas indicate the best times to schedule explosive events. This report documents the theory behind SIPS as well as the program's evolutionary process. The different computer models that make predictions about sound distribution are approximately equivalent in their predictive power with different methods of getting results and displaying the output. The quality of SIPS predictions is enhanced by using the model only on days when the weather is stable. In addition, predictions of focusing should be considered as areas rather than points since there is a tendency for them to drift.

Performance of Urban Rail Transit System: Vibration and Noise Study

Abstract: Vibration and noise are two major factors in the performance assessment of rail transit systems, particularly in an urban environment where elevated systems are used. A program of field measurements was conducted in Singapore on an elevated section of straight tracks to monitor the rail vibrations and noise generated during the passage of trains. Field measurements included impact hammer tests to determine the driving point impedances of the train wheel and track support system. These tests are relatively easy to perform, requiring only an inverted wheel-set-and-bogie assembly at the workshop and the tracks at the test yard. An analytical train model was developed to predict the level of rolling noise at the wayside of the tracks for comparison with measured levels. The analytical predictions from the model were found to be in good agreement with field measurements. A hybrid approach involving a finite-element model of the track support system and impact hammer test results was also presented to determine...

Characterisation and measurement of noise levels in an urban environment

Abstract: The existing noise pollution status of Nagpur urban environment with emphasis on objective measurement and subjective reaction of the people is reported. Road traffic noise has been a major contributor to the annoyance which is substantiated by the results of continuous monitoring of noise equivalent levels (Leq) at a number of residential, commercial, sensitive and industrial areas during day and night. The transportation network and vehicular noise at various intersections of the city have also been studied. Public participation, education, traffic management, proper land use, proper designing of building and green belt play a major role in noise abatement.

Effectiveness of noise barriers on an interstate highway: a subjective and objective evaluation

Abstract: The objective of this study was to determine the actual and perceived effectiveness of noise barriers along interstate highways. Using a 5-mile section of Interstate 71 in the greater Cincinnati area as the study area, traffic noise readings and opinions of residents living along the sections of the highway were recorded. Noise readings were taken before and after the noise barriers were erected. A questionnaire was designed to elicit noise-related annoyance of the residents in the areas adjoining the highway. The results indicated that, in general, noise barriers were effective as indicated by a reduction in noise levels by as much as 11 dBA. The barriers, however, failed to bring noise levels for locations closer to the highway within the levels desired by the government (67 dBA). Most residents living right next to the highway were very satisfied with the installation of noise barriers. In general, these individuals felt that the quality of life improved with the noise barrier installation. The same, however, was not true of residents living a few blocks away from the highway--they felt the noise barriers were a waste of money. There was no significant difference in traffic noise pattern during the weekdays or weekends. Noise readings taken in two different locations were observed to be similar.

Adana kentinde gürültü kirliliği üzerine bir araştırma

Abstract: Determination of no ise pollution at quarters of Seyhan and Yuregir in Adana has been searched to determine the source of noise, and measuring merse amount in order to do noise pollution map and improving alternative sollutions have been aimed. Important source of noise such as conveyance, Industry construction, settlement, and commerce centers have been determined. The noise amount has been measured at the 240 different points to do noise mapping. in order to determine the sensivity at inhabitants againts to noise, an inquire has been applied by using standart forms. Ali at the measurement results have been indicated the allocation of the noise density in the research area. However measures which are prevent or reduce noise have been improved by taking datas obtaincd from inquires into consideration.

Improved adaptive audio systems

Abstract: A Public Address System employing a sample and hold technique, in which the level of acoustic output is adapted to the prevailing levels of acoustic noise, so as to minimise noise pollution and to maximise intelligibility. In the absence of public address announcements, the sample-and-hold circuit 2 constantly adapts the gain 1 of the public address system message channel such that if an announcement were made, its acoustic level would be appropriate to the prevailing level of acoustic noise at the time that the message began. In this way, the ambient noise sampling system is prevented from confusing the acoustic level of the PA message with acoustic ambient noise, thus avoiding regenerative "lock up". Noise signals picked up by a microphone 11 are applied to the sample and hold circuit 2 via circuitry 12-22. The sampling is inhibited by circuitry 3-7 responsive to the message signals. The sample and hold circuit is briefly enabled during pauses in the message for updating, the gain to current noise levels. A monostable 7 is for inhibiting changes caused by echoes, reverberation. An attack and decay circuit 18 prevents changes in noise output caused by transient phenomena e.g. coughing.

Noise in intensive care units. Noise reduction by modification of gas humidification

Abstract: Today, noise pollution is an evident and ubiquitous problem even in intensive care units. Noise can disturb the physiological and psychological balance in patients and staff. Especially intubated patients and those breathing spontaneously through a T-piece are exposed to the noise emitted by the nebuliser used to humidity the respiratory gas. This may make patients feel uncomfortable. To reduce noise pollution in the ICU a modified T-piece has been developed and investigated. In order to heat and humidity the respiratory gas a Conchaterm III unit (Kendall company) and a thermo flow cylinder (De Vilbiss company) is necessary. While respiratory gas is flowing, water is sucked out of the heated thermoflow cylinder and nebulised according to the Venturi-Bernoulli principle. To adjust the oxygen concentration of the respiratory gas a plastic ring must be turned to either close (98% oxygen) or open a valve allowing room air to mix (40% oxygen). Noise pollution of the unit varies with admixture of room air. With a new device--a special oxygen-air mixing chamber--the oxygen concentration of the respiratory gas can be adjusted outside the thermoflow cylinder, hardly producing any noise pollution. Therefore the principle of nebulisation could be changed to humidification. A thermoflow cylinder without the nebulisation unit allows the respiratory gas to flow through the thermoflow cylinder over heated and evaporating water, hardly causing any noise pollution. In both types of T-pieces the temperature of the respiratory gas is controlled and corrected by the Conchaterm unit. As the result of these modifications, noise pollution has been reduced from 70 dB(A) to 55 dB(A). In the modified T-piece, the quality of humidification has been evaluated with a fresh gas flow of 22 l/min and at a gas temperature of 37 degrees C, not only collecting condensed water but also lost water. The modified T-piece allows a physiological humidification of the respiratory gas. The modified T-piece is a simple and efficacious substitute. Patients and staff are protected from adverse noise effects and patient well-being might be improved.

Federal Interagency Committee on Aviation Noise: 1994 Annual Report.

Abstract: : The Federal Interagency Committee on Aviation Noise (FICAN) was formed in 1993 to provide forums for debate over needs for future aviation noise research and to encourage new development efforts in this area. All Federal agencies concerned with aviation noise are represented on the Committee, including the Department of Defense, the Department of the Interior, the Department of Transportation, the Environmental Protection Agency, the National Aeronautics and Space Administration, and the Department of Housing and Urban Development. FICAN's 1994 Annual Report provides information on FICAN activities during calendar year 1994, including: four FICAN meetings, publication of a Report on Aviation Noise Research Conducted by U. S. Federal Agencies, a public forum, and attendance and staffing of an exhibition booth at the Third Annual Airports Council International North America Conference.

Federal Interagency Committee on Aviation Noise: Report on Aviation Noise Research Conducted By U.S. Federal Agencies.

Abstract: : The Federal Interagency Committee on Aviation Noise (FICAN) was formed in 1993 to provide forums for debate over needs for future aviation noise research and to encourage new development efforts in this area. All Federal agencies concerned with aviation noise are represented on the Committee, including the Department of Defense, the Department of the Interior, the Department of Transportation, the Environmental Protection Agency, the National Aeronautics and Space Administration, and the Department of Housing and Urban Development. This report introduces current and planned research topics in aviation noise. The work summarized here represents the individual (or sometimes joint) initiatives of member agencies. Fifty-nine projects on aviation noise were identified by FICAN members. Areas of study include: investigation of new criteria for determining land use compatibility, examination of community reactions to aircraft noise, perception of aircraft noise and how it is affected by background noise, acoustic issues associated with rotary wing aircraft, noise effects on animals, development and improvement of computer models, noise reduction technologies, improved public information materials, and structural damage effects.

Room noise criteria–The S12.2-1995 standard raises serious technical and economic considerations

Abstract: The key issue with the S12.2-1995 standard is not the differences in the assessment of sound quality, particularly at the low frequencies, but rather the use of octave-band data to describe low-frequency equipment misbehavior. Unfortunately, the "NCB vs RC" controversy leads research efforts and technical discussions in the wrong directions, disregarding serious economic and technical considerations. This conflict can be resolved by: (1) avoiding the use of octave-band data to rate noise with abnormal (spectral and/or temporal) characteristics, (2) addressing the widespread need for the room noise criteria as a practical design tool for general use in architectural spaces, and (3) developing adequate descriptor/procedures to qualify, quantify, and determine the impact of "rumble" on human response. A further goal should be to develop integrated criteria that would apply to both HVAC and computer noise sources.

Low noise pneumatic motor

Abstract: The utility model discloses an inflammable and explosive pneumatic motor. The structures of a stator and a rotor of the motor are the same as the structure of a vane pump; the outside of the stator is sheathed with a silencing casing which is provided with a through hole; gas is exhausted by a special exhaust pipe; gap is arranged between the silencing casing and an outer housing. The utility model has the advantages of simple structure and good noise reduction effect. The utility model solves the problem of the pneumatic motor of noise pollution and can be used in places with high environmental requirements.

Traffic demand management energy and the environment

Abstract: The increasing level of motorized traffic, not only in towns and cities but also in the rest of the country, has become a major cause for concern. This is not just because of worsening accessibility and road safety but also because of the adverse impact on the environment and the consequences for the general quality of life. Some direct effects include the emission of nitrous oxides (NOx) and CO2, noise and odorous pollution, smog and acidification. Motor vehicles, whether moving or stationary, take up a lot of space. In short, as a result a long term social development may be threatened. Based on the results of preliminary research which included an account of the areas for special attention, the following objectives have been set out: procuring information on the aims, methods of execution and results of traffic management projects at various levels of territorial scale, particularly aimed at limiting energy consumption; limiting noise pollution; limiting the emission of noxious chemicals.

Impact of Noise Pollution on Worker's Health of Cement Plant

Abstract: Noise is a dangerous form of environmental pollution. It can be defined as sound without agreeable quality or as unwanted sound. In cement industry, the problem of noise has got accentuated due to increased mechanization. The prolonged exposure to high levels of noise (>90 dBA) proves harmful and may culminate in Noise Induced Hearing Loss (NIHL). Not only this, it also brings other physiological disorders which could lead to irritability and lowering of efficiency. Keeping this into the mind, before initiating any sort of administrative, engineering and medical measures against this noise hazards, a systematic noise survey are essential. These help in identifying the noise pollution sources and quantifying the risk exposure of workers. And then accordingly effective anti-noise measures can be formulated and implemented. The present paper discusses the results of the noise studies in cement plant and analyses the leq(dBA) produced by different machinery in this plant. It also focuses the adverse effects of noise on worker’s health as well as the audiometric study of the workers. Lastly some suggestions has beenmentioned for protecting the worker’s health from noise

Noise pollution-an overview.

Abstract: A historical review of the medical literature dating back to 16th century describes Cannoneer's hearing loss. In the late 18th and early 20th century, the term \"boiler makers ear\" was commonly used as a noise induced hearing loss (NIHL) for those working in boiler factories. This form of noise induced occupational hearing loss was seen, as modern warfare and aviation become more sophisticated. Following the Second World War, the U.S. government spent millions of dollars rehabilitating thousands of veterans suffering from permanent NIHL. According to a conservative estimate, compensation of industrial workers in U.S.A. for NIHL exceeds 20 billion dollars and a staggering 35 million Americans suffer from hearing loss, thereby making occupational hearing loss as the Number One medicolegal and environmental problems in U.S.A.

City Noise: Report of Urban Noise Task Force of the City of Vancouver

Abstract: The most significant noise sources identified in the telephone survey were noise related to traffic, specific types of vehicles and sirens, followed by noise from parties. Other major noise sources that were identified were noise related to gardening, aircraft, alarms, garbage dumpsters, and special public events. Public input highlighted how noise is a symptom as well as a cause of social stress, and it raised issues regarding the cultural significance of sound, quiet, and noise.

Development of the DLR “Smartsound” noise adaptive public address control system

Abstract: The Docklands Light Railway (DLR) is a light rail rapid passenger transit system which serves the needs of residents and businesses within the London Docklands regeneration zone. DLR has a policy on noise which states the intentions of the company for the system-wide control of noise arising from train operations and sets down target maximum noise levels at adjacent buildings. In locations where the target levels are exceeded, DLR is committed to using best practicable means to minimise the levels of exterior noise at source. The "Smartsound" noise adaptive public address (PA) control system was first developed out of a need to resolve specific problems connected either with the inadequate transmission of announcements to passengers on stations during periods of intrusive background noise, or with unwanted overspill of the PA sound into neighbouring properties. The success of "Smartsound" has resulted in the development of a new control of environmental noise pollution whilst enabling the railway to maintain not only good communication with its passengers but also enhancement of customer safety and assurance through intelligible announcements when it matters most.

Noise and vibration

Abstract: The main concern regarding environmental noise and vibration is its effect on people within buildings: in their homes and at their places of work. The noise problem may arise from external sources, such as traffic, and internal sources, such as machinery in factories. In addition to the problem of noise-induced hearing loss, there appears to be an increasing public awareness of noise pollution and its impact on the quality of life. This concern has become more widespread and is no longer centred primarily on specific localities such as near airports.