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David Southgate, Department of Transport and Regional Development (Australia)
P. Pieruschka, Department of Transport and Regional Development (Australia)
Following the opening of the new `third runway' at Sydney Airport in November 1994 there was a public outcry over the way future noise impacts had been explained during the Environmental Impact Statement (EIS) process for the project. There was a widespread view that the award winning EIS had been grossly misleading. Using the third runway EIS as an example, this paper examines the weaknesses of the conventional approach to describing noise through cumulative noise indices. Complex `averaging' noise indices can not generally be understood by the layperson and do not provide information in a useful form. Instead the public is seeking information that is more readily digestible. To meet this demand information is being provided on flight paths, the number of noise events per hour, the maximum noise level of each event and the amount of time per day when areas will receive `respite' from noise. Information on daily and seasonal variations in noise exposure is also being provided. This paper shows new approaches to describing aircraft noise exposure that have been trialed in recent formal reports and discusses their potential.
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Stephen Samuels, University of New South Wales (Australia)
Weeradej Cheewapattananuwong, Department of Highways (Thailand)
Road traffic noise has been an issue of significance within the developed world for many years now. More recently it has been of increasing importance in the developing nations. This is particularly so in the South East Asian region where surging economic growth and development has resulted in considerable expansions to the road transport infrastructure networks. Bangkok, the capital of Thailand, provides a good example of this situation. The city is located on the Easter bank of the Caho Phraya River, with the sister city of Thon Buri situated on the river's Western bank. Cross river traffic is high and increases dramatically during peak hours. Baromrajchonne Rd is a major arterial road in central Bangkok which is significantly affected by this cross river traffic and therefore a project is under way (at Thai Royal initiation) to upgrade Baromrajchonne Rd by adding several kilometres of elevated section. During construction, traffic congestion has been extreme and this has led to increased traffic noise levels. The paper focuses on this particular traffic noise issue and uses Baromrajchonne Rd as a case study example. Having explored the issue in some detail, the paper culminates with a series of amelioration strategy proposals.
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Tony Circelli, South Australian Environmental Protection Authority (Australia)
Cecilia Bukutu, South Australian Environmental Protection Authority (Australia)
A preliminary study was carried out to investigate the acoustical effectiveness of residential multiple occupancy dwellings located on North East Road, Adelaide which were designed to reduce the adverse impact of traffic noise. Noise measurements were taken both at night and day. Indoor and outdoor LAeq, LA10, LA90, LA01 and LAmax were obtained simultaneously every 15 minutes over a six day period. The investigation determined both the mean outdoor and internal noise and the resulting mean outdoor to indoor noise attenuation for each noise descriptor. The internal noise levels were compared with selected traffic noise criteria. It was found that the resulting amenity within the acoustically upgraded dwelling was superior to conventional construction dwellings. Resulting internal noise levels generally satisfied the Shire of Hornsby Building Code criterion. However OECD criteria based on the LAeq and the LAmax noise level were exceeded.
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Ernestine M.A. Gross, Macquarie Graduate School of Management (Australia)
Ah Boon Sim, University of New South Wales (Australia)
The Australian Noise Exposure Forecast (ANEF) system was applied in Sydney in the decision making process which led to the construction of the 'third runway'. After the opening of this runway in November 1994, a predominantly north-south parallel runway mode of operation was adopted. The Environmental Impact Statement for the third runway and the associated Draft Noise Management Plan (DNMP) predicted, on the basis of the ANEF system, and data contained in Hede and Bullen (1982), that the number of 'at least moderately affected' or 'seriously affected' residents will be zero in the local government area of Ku-ring-gai. This local government area of approximately 106,000 residents is located at least 15 and as much as 30 kilometres north of Sydney airport and is primarily exposed to aircraft landing from the north. This paper reports on the major findings of a questionnaire survey, carried out in September 1995, involving a sample of 5000 randomly selected voters of Ku-ring-gai and using a questionnaire which is essentially identical to that used by Hede and Bullen (1982). The results show that the DNMP underestimated the number of aircraft noise affected people by at least 13 per cent on the basis of the local government area of Ku-ring-gai alone.
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Manuel Recuero, Universidad Politecnica de Madrid (Spain)
C. Gil, Universidad Politecnica de Madrid (Spain)
J. Grundman, Universidad Politecnica de Madrid (Spain)
In this work the results of a 20-question survey about the acoustic environment made on the population of 17 towns are presented. Up to 7141 questionnaires were distributed, where 3272 were conducted in population centers with more than 100000 inhabitants, 2695 in towns below 100000 and above 50000 inhabitants and 1174 in towns with less than 50000 inhabitants. The aim of this statistical work is to estimate the citizens' opinion about noise sources in their municipalities, the annoyance that these sources produce, where and when the effect seems stronger and how the noise affects residential areas. There were also questions concerning the opinion about protection against noise in dwellings and the presumed effects of environmental noise. Finally, it was intended to know how important the residents think the environmental noise problem is, how deep is their knowledge about their rights and the law and what do they think about possible measures to improve the situation.
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Peter Karantonis, Renzo Tonin & Associates Pty Ltd (Australia)
Najah Ishac, Renzo Tonin & Associates Pty Ltd (Australia)
Renzo Tonin, Renzo Tonin & Associates Pty Ltd (Australia)
Concern has been shown over the misuse of engine compression brakes in urban areas. This Is of particular Interest when heavy vehicles have defective, missing or non-approved mufflers fitted. While operators of heavy vehicles fitted with such auxiliary brakes state that they are used for safety reasons, previous studies suggest the use of supplementary brakes is purely to lower costs (ie reduce brake lining wear). The overall primary objectives of the research conducted by Renzo Tonin & Associates Pty Ltd were to: evaluate the relationship between brake lining temperatures and compare temperatures to manufacturer safety limits; evaluate the relationship between service brake wear and engine compression brake usage; address the anecdotal evidence concerning adverse fuel consumption associated with standard versus after-market mufflers; Investigate engine compression brake noise levels associated with standard versus after-market mufflers.
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Momir Prascevic, University of Nis (Yugoslavia)
Dragan S. Cvetkovic, University of Nis (Yugoslavia)
A.S. Deljanin, JP PTT (Yugoslavia)
V.O. Stojanovic, Advanced Technical School (Yugoslavia)
The traffic noise, as main source in urban areas, makes up part of general environment problem which inflicts serious damage to the health of human beings and lowers their labor productivity. With little or no noise abatement legislation and by disregarding eventual noise control measures in sound source themselves and in urban environments, the traffic noise in cities may grow up alarmingly due to continued development of transportation infrastructure, to higher unit capacities and speeds of motor vehicles. Therefore, the control of traffic noise has become a matter of major concern for communities trying to maintain a satisfactory environment in which to live and work. In order to modeling traffic noise and selecting corresponding noise controi measures it is necessary to know functional relationships between noise emission and certain numbers of traffic parameters. The noise levels can be predicted by a mathematical model while designing planning and developments schemes for new transportation routes and re-development of existing ones or when the flow and composition of traffic are changed, in this paper, the results of modeling road traffic noise level by trending of the experimental data collected by systematic noise measurement at 11 measurement points in urban areas of Nis will be shown,
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Thomas E. Reinhart, Cummins Engine Company (U.S.A.)
Thomas J. Wahl, Cummins Engine Company (U.S.A.)
Compression brakes are typically installed on heavy trucks, and operated when the truck is going downhill, although drivers sometimes use them on level ground. The noise generated by compression brakes can be a source of excessive traffic noise. A test procedure is required in order to understand compression brake noise, develop improvements, and form the basis for regulation of brake noise. The challenge in developing a brake noise test procedure is to design a test which is simple and repeatable, while accurately simulating the noise generated under normal operating conditions. The test method proposed here is based on the standard ISO 362 acceleration driveby test. In the new procedure, an unladen truck enters the test track at high idle (maximum achievable engine speed), and decelerates past the microphones with the compression brake on. Extensive test results demonstrate that a relatively low speed test with an unladen truck provides a valid simulation for the brake noise of a fully laden truck going down a hill. The repeatability of the proposed test is also demonstrated, along with the sensitivity of the results to changes in test parameters.
sv970404.pdf (Scanned) TOPMarion Burgess, Australian Defence Force Academy (Australia)
The Residential Insulation Scheme is an important part of the Sydney Airport Noise Amelioration Project. This scheme is based on the application of treatments from a Menu based on the external aircraft noise. Following implementation in over 400 houses the acoustic data obtained from measurements in a sample of 61 houses before and after treatment have been analysed. The aim of the analysis was to assess the effectiveness of the insulation scheme and in particular to ascertain if improvements or changes were necessary. For the majority of the sample, the aircraft noise attenuation achieved for the bedrooms was as would be expected. The reasons for lower than expected attenuation were identified for the others. Two important finding from the study were that kitchens and living rooms are likely to achieve lower attenuation than bedrooms and that attention to detail in the inspection process is essential. It was also found that while the use of the Menu appears to be an effective and fair means for choosing the appropriate measures, there is some scope for simplification.
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Patrick Van de Ponseele, LMS International (Belgium)
S. Campino, Universite de Technologie de Compiegne (France)
Filip Deblauwe, LMS International (Belgium)
Geert Lowet, LMS International (Belgium)
Too often car manufacturers are confronted with noises inside the passenger compartment. The solution to such a problem has quite often been one from try and see. However, in the last five years new tools, such as transfer path analysis, have been developed. These tools have been a great help in understanding the contribution of the different components, such as engine, exhaust etc., to the total interior noise. The new techniques also provide the capability of modifying the path of the different components and estimate anew spectrum of the interior noise of the car. However in all these new powerful and useful tools there is still one missing link. It is very hard to judge the impact of the modifications on the sound perception solely based on a spectrum. One can only judge the modifications to its full extend when one can listen to the modification. This paper describes how transfer path analysis has been integrated and the modification of low engine orders in a sound quality package to provide the possibility to evaluate the modifications from a sound quality standpoint. The main challenge for this problem is to only modify the components in the original signal that are influenced by the transfer path analysis without losing the other components that guarantee the background color of the sound.
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Yong Seok Kim, Korea Advanced Institute of Science and Technology (Korea)
Duck Joo Lee, Korea Advanced Institute of Science and Technology (Korea)
Traditionally, intake noise from internal combustion engine has not received nearly as much attention as exhaust noise. But nowadays, intake noise is a major contributing factor to automotive passenger compartment noise levels. In this study, compressible Navier-Stokes eqns are employed numerically for the intake stroke of axisymmetric model having a single cylinder and a single intake valve. The main objective of this paper is to identify the mechanism of generation, propagation and radiation of the intake noise. The main noise source for the intake stroke was found to be the pressure surge which is generated after intake valve closing. The pressure surge which has the nonlinear acoustic behavior propagates and radiates with small attenuation. To simulate the periodic motion of the piston and valve, unsteady deforming mesh algorithm is employed and Thompson's non-reflecting boundary condition is applied to the radiation field. In order to resolve the small amplitude waves and the radiation field, essentially
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Thomas E. Reinhart, Cummins Engine Company (U.S.A.)
Thomas J. Wahl, Cummins Engine Company (U.S.A.)
This study examines compression brake noise levels in heavy-duty diesel trucks, using test procedures based on the ISO and EPA driveby acceleration noise tests. The data shows that compression brake noise levels are very high if worn out or open stack exhaust systems are used. Compression brake noise is also audible with OEM exhaust systems and, in at least one case, potentially objectionable. This study also describes the time and frequency domain characteristics of compression brake noise. Brake noise is dominated by strong pressure impulses which repeat at one of the first three harmonics of engine firing frequency. The subjective quality of brake noise is primarily determined by medium and high frequency noise which is produced by the periodic pulses. No useful correlation between brake performance parameters and noise levels is found. Two methods for reducing brake noise are investigated: improved mufflers and the use of an exhaust brake with the compression brake. Both techniques demonstrate a potential for reducing compression brake noise, but an improved muffler is far more cost effective.
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