Botteldooren, Dick

De Coensel, Bert

de Greve, Bram

Dekoninck, Luc

LERCHER, P

Undetermined

Ghent University Academic Bibliography

                                      19th INTERNATIONAL CONGRESS ON ACOUSTICS                          MADRID, 2-7 SEPTEMBER 2007                                                                        ANNOYANCE BY COMBINED EXPOSURE TO NOISE FROM ROAD TRAFFIC AND RAIL TRAFFIC DISCUSSED IN THE FRAMEWORK OF THE NOTICING MODEL  PACS: 43.50.-x, 43.50.Qp, 43.50.Sr  Botteldooren, Dick1, Dekoninck, Luc1, de Greve, Bram1, De Coensel, Bert1, Lercher, Peter2 1Ghent University, Department of Information Technology, Sint-Pietersnieuwstraat 41, B-9000 Gent, Belgium; Dick.Botteldooren@intec.Ugent.be 2Medical University Innsbruck, Department of Hygiene, Microbiology and Social Medicine, Austria  ABSTRACT The effect of combined exposure to noise from different sources is a multifaceted problem. It has previously been explained using a two step model. The first step consists in quantifying the effect of noise from one source in the presence of noise from the other source. The second step is overall assessment of ones exposure situation. The latter part of the problem has been explained quite well while the first part seems to be less understood. In this paper we gathered a number of annoyance survey data and the results of a field experiment and discuss observations in the light of the noticing model that we have developed over the past couple of years. In this model noticing a noise during everyday activities is a critical condition for annoyance to occur. Noticing of intermittent sources such as railway noise is governed mainly by the peak level of the sound while noticing more continuous sound depends on momentaneous attention. Combined exposure both leads to adaptation and habituation at one hand and to focussing triggered by the other source at the other hand. The proposed model predicts some of the trends in the data.  INTRODUCTION  The effect of combined exposure to several sources of noise has been a focus of interest for many years. Early research [1-2] in this area already distinguished between the influence of the presence of a second source on the perceived annoyance caused by the first one at one hand and an overall assessment of noise annoyance on the other. Studies on the latter effect have been quite conclusive in their finding: providing that the overall annoyance question is posed prior to discussing categories of possible noise sources, the strongest component model predicts reported overall annoyance quite well. In [3] we gave an overview of existing models and propose a cognitive model that explains the answers obtained in questionnaire surveys.  Understanding the influence of the presence of a second noise source on annoyance caused by a first one, is much more complicated. Earlier work [4] showed that noise sensitivity of people living close to highways was lower and thus annoyance caused by other forms of sound such as railway noise was less in these areas compared to the average situation. Lower sensitivity was thought to be mainly caused by migration of less sensitive people into the area. The acoustical factor nevertheless plays a significant role. It should allow distinguishing between sources. In [5] a very simple model is proposed that consists in adding equivalent noise levels that cause the same amount of annoyance. Several variants on this theme were proposed but they all have in common that they are based on an equivalent noise level as a primary indicator.   In this paper we study annoyance caused by combined exposure to road and rail traffic noise within the framework of the notice-event model for noise annoyance that was previously proposed [6-7]. It was shown that this model could explain much of the difference in annoyance between highway traffic noise exposure and railway traffic noise exposure that is commonly observed in questionnaire surveys and field experiments.   A SUMMARY OF OBSERVATIONS Before considering the effect of cumulative exposure, the inaccuracy in trying to explain railway noise annoyance as a function of equivalent sound level (or Lden) has to be recognised. In    19th INTERNATIONAL CONGRESS ON ACOUSTICS – ICA2007MADRID 2Figure 1b annoyance observed in a large scale retrospective noise annoyance survey (using a standard annoyance question) conducted in Flanders is plotted as a function of calculated railway noise level grouping data by distance to the railway line. The observed trend significantly depends on the distance to the track (standard error is indicated). This observation is not unique and has been explained in several different ways. Amongst others combined exposure to noise and vibrations has been mentioned as a possible cause for the increased annoyance. However, in a field experiment [8] we observed a very similar trend (Figure 1a) although vibrations were not reproduced. The various dots in this figure correspond to particular combinations of types and numbers of trains. These and comparable observations were explained by a noise annoyance model where noticing sounds plays a crucial role [6, 7]. -1001020304050607030 40 50 60 70 80LAeq,10min [dB(A)]annoyance [master scale units] short distancelong distance1 2 3 4 30 40 50 60 70Lden Rail [dB(A)]Average noise annoyance distance >300mdistance <300m    (a)      (b) Figure 1.- Railway noise annoyance versus equivalent sound level for close and far railway as observed in a) a field experiment; b) a nationwide retrospective survey.  When analysing the effect of high road traffic noise levels on annoyance caused by railway noise we therefore distinguish by distance. Figure 2 shows Lden-annoyance curves for highway Lden above, approximately equal to and below the railway Lden and this for short distance and longer distance to the track as observed in the Flemish survey. Although results are only marginally significant, there is a clear trend for the presence of road traffic noise to reduce rail traffic noise annoyance. This is particularly true at larger distance from the track. The reverse analyses shows that the exposure effect relationship for road traffic noise annoyance is almost not affected by the presence of rail traffic noise. 1235 40 45 50 55 60 65 70 75LDEN Rail [dB(A)]Average annoyanceequalrail > roadrail < road123435 40 45 50 55 60 65 70 75LDEN Rail [dB(A)]Average annoyanceequalrail > roadrail < road    (a)      (b) Figure 2.- Railway noise annoyance versus Lden for road traffic noise levels roughly equal (within +- 5 dB(A)) and for road traffic noise levels above / below the rail traffic noise level (Flanders): (a) beyond 300m from the track; b) within 300m from the track. Exactly the same analysis was performed on noise survey data obtained in the lower Inntal (Austria). Again a standard formulation of the noise annoyance question was used, but the survey as a whole was much more elaborate. The exposure situation is considerably different because the railway track and highway virtually run in parallel along the valley axes. This also implies that the source is much more similar (same number of trains) at all survey locations. Figure 3 shows that at larger distance from the track, trends are very similar as in Figure 2. At shorter distance, things get a little obscured. This is partly explained by the rareness of situations where the road traffic noise dominates rail traffic noise at close distance to the track, partly by the presence of noise barriers along large portions of the track. The latter may cause a change in noise exposure that is not well captured by the Lden.     19th INTERNATIONAL CONGRESS ON ACOUSTICS – ICA2007MADRID 312335 40 45 50 55 60 65 70 75 80LDEN Rail [dB(A)]Average annoyanceequalrail>roadrail<road123435 40 45 50 55 60 65 70 75 80LDEN Rail [dB(A)]Average annoyanceequalrail>roadrail<road    (a)      (b) Figure 3.- Railway noise annoyance versus Lden for road traffic noise levels roughly equal (within ± 5 dB(A)) and for road traffic noise levels above / below the rail traffic noise level (Lower Inntal): (a) beyond 300m from the track; b) within 300m from the track.  To analyse in more detail the influence of road traffic noise exposure on railway noise annoyance, the percentage of moderately or highly annoyed people is shown in Figure 4 as a function of road traffic noise exposure. For lower levels of road traffic noise, there is again a vague trend of decreasing annoyance with increasing road traffic Lden. At higher noise levels, this trend seems to turn to an increase. The turning point seems to lie around 65dB(A) except for lower rail noise exposure where this level has the tendency to be somewhat lower. It has to be noted that there could be secondary effects influencing this trend, e.g. road traffic noise levels of about 65 dB(A) occur in urban areas where many other sound sources contribute to the soundscape as well.  0%10%20%30%40%50%60%45 50 55 60 65 70LDEN Road [dB(A)]% moderately or highly annoyed455055606570 Figure 4.- Percentage of population moderately or highly annoyed by railway noise within 300m from the track versus Lden,road for different levels (Lden) of rail traffic noise.  ANSWERS GIVEN BY THE NOTICE-EVENT MODEL The notice-event model [6-7] tries to clarify human reaction to sound by accurately modelling the exposure to intruding noise taking into account personal situation, background noise, and psycho-acoustic mechanisms such as adaptation, habituation, focussing, and coping. As the name suggests, a key feature of the model is analysing which environmental noises will be noticed during everyday activities. Rather than to show results of extensive simulations (for which we refer to the work cited above) we discuss how this model would explain the observations made in the previous paragraphs.  Consider a noise event such as a train passage. Whether this event is noticed by a person minding his daily activities depends on many factors of which, obviously, the level of the event is an important one. Because of the many personal and situational factors, one can only make probabilistic statements based on level alone. Above a certain threshold (Figure 5), train passages will often be noticed (P>0). If the level is extremely high passages will always be noticed (P=1). In between these two lines, probability gradually increases. When train noise is considered on its own, it can be expected that adaptation, habituation, and different styles of coping will gradually increase the threshold of noticing. Focussing on the other hand may lower this threshold.     19th INTERNATIONAL CONGRESS ON ACOUSTICS – ICA2007MADRID 4What if highway noise is added to this picture? Masking will only occur for fairly low peak levels and even lower equivalent noise levels and thus is probably important only for very particular situations. Adaptation, habituation and coping can reasonably be expected to act across sources, in particular when one of the sources – road traffic noise in this case – is rather continuous. It can be expected that this shifts the level where the probability of noticing a train passage reaches 1. In addition, highway noise acts as background noise for noticing train passages, in particular when levels are sufficiently low. The reduced signal to noise ratio decreases the overall probability of noticing. This mechanism is not reciprocal. Train noise events are expected to have less influence on noticing highway noise.  Noticing a sound is an important factor, but it does not explain the whole process leading to reporting noise annoyance. In particular, appraisal partly based on cognitive association of the source to health hazards may play a role. Additional cumulative effects could be expected due to stress induced by one source of sound while appraising another one. Finally, additional effects may occur while reporting noise annoyance. The respondent may try to distinguish between sources of noise and hence modify its evaluation of one source due to the presence of the other. Some evidence of the latter effect could be found in the Flemish survey data but it seems mainly relevant for road traffic noise annoyance at low road traffic noise exposure levels, a region not very interesting for noise annoyance research. Leq,highwayLpassage,railTrain noise masked in shaded areaTrain passage always noticed above this levelTrain passage often noticed above this levelba Figure 5.- Explaining the notice event model when train and highway noise is present.  References:  [1] B. Berglund, U. Berglund, M. Goldstein, and T. Lindvall, Loudness (or annoyance) summation of combined community noises, J. Acoust. Soc. Am. 70(6), 1981, 1628-1634 [2] Powell, C.A., A summation and inhibition model of annoyance response to multiple community noise sources, NASA Technical Paper 1479 (1979) [3] D. Botteldooren, A. Verkeyn, Fuzzy models for accumulation of reported community noise annoyance from combined sources, Journal of Acoustical Society of America 112 (4), 2002, pp. 1496-1508 [4] D. Botteldooren, A. Verkeyn, P. Lercher, How can classical analysis and fuzzy modeling help us find out how road noise modifies people's reaction to railway noise ?, Proceedings of Inter-noise 2001 [5] Miedema, H.M.E., Relationship between exposure to multiple noise sources and noise annoyance, J. Acoust. Soc. Am. 116 (2), 2004, pp. 949-957 [6] De Muer, T., D. Botteldooren, B. De Coensel, B. Berglund, M. Nilsson, P. Lercher, A model for noise annoyance based on notice-events, Internoise 2005. [7] De Muer, T., Policy Supporting Tools for Urban Noise Assessment., PhD Dissertation UGent 2006 [8] Bert De Coensel, Dick Botteldooren, Birgitta Berglund, Mats E. Nilsson, Tom De Muer, Peter Lercher, Experimental Investigation of Noise Annoyance caused by High-speed Trains, accepted for Acta Acustica united with Acustica, 2007            

Annoyance by combined exposure to noise from road traffic and rail traffic discussed in the framework of the noticing model (invited paper)

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Annoyance by combined exposure to noise from road traffic and rail traffic discussed in the framework of the noticing model (invited paper)

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