J.G. Walker

Comparing the relationships between noise level and annoyance in different surveys: A railway noise vs. aircraft and road traffic comparison

Abstract Annoyance expressed in a railway noise survey is compared with that in two road traffic and three aircraft surveys in order to determine whether responses to various environmental noises are similar or are source-specific. Railway noise is less annoying than other noises at any given high noise level. Railway noise annoyance increases less rapidly with increasing noise level. At high noise levels this gap in reactions averages about 10 dB but ranges from 4 dB to more than 20 dB. Comparisons between the findings in the different surveys can be made only after considering differences in noise index calculation procedures, human response measurement procedures and annoyance moderating conditions. The methodology for comparing surveys is examined. It is found that methodological uncertainties lead to imprecise comparisons and that different annoyance scales give different estimates of intersurvey differences.

The response to railway noise in residential areas in Great Britain

Abstract The effects of railway noise on residents have been measured with a combined social survey (1453 respondents) and noise measurement survey (over 2000 noise measurements) at 403 locations in 75 study areas in Great Britain. In the analysis of the data methods have been used which take into account many typical noise survey problems including noise measurement errors, unique locality effects and the weakness of the noise annoyance relationship. Railway noise bothers 2% of the nations population. Approximately 170 000 people live where railway noise levels are above 65 dB(A) 24 hour Leq. Annoyance increases steadily with noise level; thus there is no particular “acceptable” noise level. Railway noise is less annoying than aircraft or road traffic noise of equivalent noise level, at least above 50 to 65Leq. Noise is rated as the most serious environmental nuisance caused by railways. Maintenance noise is rated as a bigger problem than passing train noise. Vibration is the most important non-noise problem. Reactions to vibrations are related to distance from route, train speed and number of trains. The railway surveys highly stratified, probability sample design with many study areas makes it possible to evaluate the effects of area characteristics on reactions. The 24 h Leq dB(A) noise index is more closely related to annoyance than are other accepted noise indices examined. There is no support for ambient noise level or night-time corrections. Thirteen railway operation characteristics were examined. One, the type of traction, has a strong effect on reactions after controlling for Leq (overhead electrified routes are the equivalent of about 10 dB less annoying at high noise levels). Three indicators of railway ancillary noises and non-noise environmental nuisances affect annoyance but most operational characteristics have no effect. The effects of over 35 demographic, attitudinal and neighbourhood characteristics on annoyance are examined. Though most objective characteristics of neighbourhoods and respondents are not correlated with annoyance, three do decrease annoyance (older dwellings, older respondents, and life-time residence). The attitudes which affect annoyance with railway noise are not general ones about railways as transportation sources, but rather ones which are specific to the neighbourhood setting or to railways as environmental intrusions in the neighbourhood. Such attitudes often have less effect on annoyance at low noise levels. In such cases it is the reactions of the more annoyed types of people which are most closely related to noise level.

The identification and subjective effect of amplitude modulation in diesel engine exhaust noise

Abstract The study reported in this paper examines the sourcesof diesel locomotive noise that give rise to annoyance. It is shown that the amplitude modulation present in diesel engine noise has importance in determining annoyance. The frequency and depth of the modulation are related to the fundamental firing frequency, the firing frequency of the engine and exhaust manifold design. Changes in the manifold design could reduce the adverse subjective response.

Temporary threshold shift caused by combined steady-state and impulse noises

Abstract Temporary threshold shift (TTS) measurements on 11 subjects, resulting from exposures to steady-state noise, impulse noise, and combinations of both types of noise are reported. Twenty minute exposures to wide-band steady-state noise at levels of 78, 84, 90 and 96 dBA, and impulse noise at levels of 96, 102, 108, 114, 120, 126 and 132 dB(peak), and repetition rate of 3·2 pulses/s, were used. When a hazardous level of steady-state noise was combined with various levels of impulse noise, there was a significant reduction in the measured TTS at 4 and 6 kHz. This reduction was greatest when the peak level of the pulse exceeded the r.m.s. level of the steady-state noise by 6–18 dB. When a hazardous level of the pulse was combined with several levels of steady-state noise, no significant reduction in TTS was observed. These findings are interpreted as a result of acoustic reflex stimulation; the pulses superimposed on a hazardous steady-state noise continually re-activated the reflex and prevented fatigue. The converse did not apply, that is, the non-hazardous (but high-level) steady-state noise did not appear to counteract fatigue resulting from hazardous impulse noise.

Railway noise exposure: A possible method of establishing criteria for acceptability

Abstract This paper reviews an earlier study carried out in Great Britain, which has compared annoyance responses to aircraft, road traffic and railway noise. It is concluded that sufficient information exists to enable differences in responses to road traffic and railway noise to be estimated. The paper proposes that these estimates can be used to formulate guidelines for criteria for railway noise exposure.

Factors affecting railway noise levels in residential areas

In order to be able to estimate noise levels in residential areas it is important to understand the mode of propagation of railway noise in open ground conditions. Experiments were conducted to investigate the effect of train type and speed as well as distance from the track on measured noise levels. The presence of cuttings and embankments as well as the houses themselves also affect the noise levels. Data are presented which show the effect of all these parameters and a simple procedure is outlined that allows the maximum noise level at any position in a residential area to be estimated.

Problems associated with the reproduction of impulse noise for TTS studies and impulse noise measurements

Abstract Temporary threshold shift (TTS) measurements resulting from exposures to live and tape recorded impulse sounds were carried out on four subjects. The results show that there is a significant difference between the two measured values of TTS 2 , and that the rise time and frequency response of the reproduction system are important factors in determining this difference.

Studies in hearing conservation

This paper together with two companion papers comprise a review of the greater part of the research on hearing conservation carried out over the past ten years at the Institute of Sound and Vibration Research of the University of Southampton. The research described in this paper includes studies of temporary threshold shift from exposure to impulse noise and to mixtures of continuous and impulse noises, the establishment of damage risk criteria for gunfire and other types of impulse noise, the hazards to hearing from ultrasound and studies on the measurement of the attenuation of hearing protection. The current state of ideas and research in these aspects of hearing conservation are discussed together with indications of possible future trends and requirements. Recent work on the extension of the damage risk criteria studies to the establishment of an equal energy principle for hearing damage for all types of noise is described in the first of the two companion papers, by Rice and Martin; the second companion paper, by Coles and Martin, is a review of certain medico-legal aspects of hearing conservation.

Rapporteur's report, session 2: Other sources, including maintenance noise, freightyards, locomotive noise, station noise, etc.

Abstract The major sources of noise, excluding through train noise, were identified as locomotive noise, maintenance noise and freight marshalling noise. The biggest single problem appeared, from social survey data in the U.K., to be railway maintenance noise, which was difficult to control effectively. Locomotive noise was also a problem and it should be productive to diagnose the sources of noise before attempting noise control. Retarder noise, generated as squeal, was the major noise in freight marshalling yards. Again, before noise control can be effective, the mechanisms of the generation must be fully understood.

Rapporteur's report, session 3: Sources and propagation of vibration

Abstract The generation and propagation of vibration is extremely complex. The ground attenuates vibration at different rates for different frequencies. Some frequencies are propagated particularly well and this point was discussed at considerable length without any firm conclusions being reached.