Long-term evolution of noise annoyance depends on the type of transportation noise - What are the main drivers for the observed trends? Jean-Marc Wunderli 1 Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf Mark Brink 2 Federal Office for the Environment, CH-3003 Bern ABSTRACT Transportation noise annoyance has been investigated in a widely standardized way over the last decades, which allows studying the evolution of exposure-annoyance relationships over time. A temporal comparison reveals an increase of high annoyance in recent studies for railway and aircraft noise, compared to rather stable relationships for road traffic noise. Yet the reasons for these disparate developments remain only little explored. In this paper, potential explanations for the observed divergences are discussed, namely changing values and expectations in society, changing semantics of words used in survey instruments, changes in the attitude towards the different types of traffic, and changes in exposure strength and exposure characteristics. On that basis, considerations are made about the suitability of noise annoyance as a noise effect informing noise limits.

1 INTRODUCTION

Based on a plethora of socio-acoustic studies carried out in the past decades, there seems to be a clear indication of an ongoing increase of aircraft noise annoyance at a given average noise exposure level, at least until about 2010 [1, 2]. A similar trend can be observed with railway noise [3] while road traffic noise annoyance seems to have been relatively stable over time [4]. In other words, the (European) population tends to be more sensitive to noise levels from railways and aircraft that were formerly tolerated, while more or less retaining the level of annoyance from road traffic noise over the years. In this discussion paper, we explore potential explanations for these divergent observations. In particular, we ask why aircraft and railway noise annoyance has increased, whereas road traffic noise annoyance has not (or at least not that much). However, there is no full consensus in the scientific community whether these trends really exist and if they do, which potential explanations seem plausible. For aircraft noise, Brooker argued that the statistical evidence for an upward annoyance trend is rather weak (e.g. [5]) and Gjestland denied the existence of such a trend completely [6], which in turn stirred an ongoing debate [7, 8].

1 jean-marc.wunderli@empa.ch

2 mark.brink@bafu.admin.ch

Fh inter.noise 21-24 AUGUST SCOTTISH EVENT cans ee 2022

We will in this paper not try to empirically substantiate that a trend towards more annoyance (regarding aircraft and railway noise) does exist. We simply assume that it does. On the same note, this discussion paper does not present a clear-cut explanation for the question at stake, but rather adds some thoughts to the current discussion, which has already found expression in various publications [1, 2, 9] (the most notable and up to date one being the ICBEN 2017 keynote paper from Guski [2], from which we have generously helped ourselves here...). Various factors are discussed in the literature as possible reasons for the increase in annoyance, but none of them can, in our view, satisfactorily explain the observed trend. Here, we will delve into one new idea in particular, namely that the technical progress and the successes of noise abatement at the source themselves (e.g., ever quieter aircraft engines or enhancements in the railway rolling stock) may have shifted the acoustic "comfort expectations" in the population in the course of recent decades. Finally, the paper asks whether the degree of annoyance is really a suitable parameter for tightening legal exposure limits. Before doing so, we will in the next chapter briefly summarize the developments on the exposure side first.

2 OBSERVED CHANGES IN NOISE EXPOSURE FOR ROAD, RAIL, AND AIRCRAFT NOISE IN THE LAST DECADES

We will in the following shed some light on the development of transportation noise exposure, individually for the three sources under consideration. The focus will thereby be on changes of vehicle fleet emissions as well as traffic volumes, while local noise abatement strategies will not be discussed in detail. The identified general trends are based on data from Switzerland. Nevertheless, we believe that they should be comparable at least with those in other European countries. We restrict ourselves to a time period reaching back to the mid 1980's.

2.1 Emission of road vehicles

An ideal data basis for discussing changes in road traffic noise exposure are long-term measurements, including traffic counts, at representative locations. Since 2004, road traffic noise is permanently measured along the north-south highway corridor through Switzerland at four locations, as part of the project to monitor the environmental impact of transalpine freight traffic [10]. Based on this dataset, it can be shown that the emission of the vehicles, passenger cars as well as trucks, did hardly change over the years. In some cases, even an increase of emission was detected. This observation was confirmed by an extensive study that analyzed pass-by levels of approximately 180'000 vehicles at 980 locations between the years 1998 and 2017 with indicated speeds of 50, 80 and 120 km/h [11]. The authors found an average decline of emissions of passenger cars travelling at 50 km/h of approximately 2 dB, but a slight increase for trucks of 0.5 dB. At higher speeds, an average increase of levels of 1.5 and 3.0 dB was found for passenger cars and trucks respectively. These results indicate that engine noise was successfully reduced over the years, but rolling noise increased instead. Most certainly, this is due to the tendency towards heavier vehicles and thus wider tires. An alternative to assess the change of noise emission over time is to compare different emission models, as they normally rely on extensive measurement data that were collected at that time. In Switzerland, such measurement campaigns were conducted in the years 1987, 1995 and 2018, as input for the road traffic noise models StL-86 [12], StL-86+/sonRoad [13] and sonRoad18 [14]. Figure 1 shows on the left corresponding pass-by levels for passenger cars and trucks, which confirm the findings of the long-term measurements (for higher speeds), namely, very stable emissions over the years with even a slight tendency towards higher levels.

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Figure 1: Pass-by levels per vehicle category at a reference speed of 80 km/h, in 7.5 m distance. Average model values for road (left) and railway vehicles (right) are shown.

2.2 Emission of rail vehicles

To track railway noise emission levels, the Federal Office of Transport is operating a monitoring network since 2003. Figure 2 compares cumulative distributions of passenger train pass-by levels at six stations from the year 2003 with the year 2020. On average, a decrease of levels of about 10 dB is visible. For freight trains a similar reduction of levels is measured, the latter being the result of an extensive retrofit program of freight wagons in Switzerland. In addition, Figure 1 shows on the right a comparison of modelled emissions for three vehicle categories, which are based on three large measurement campaigns carried out in Switzerland. The first one was conducted in 1978 [15]. In 1990, a reevaluation was done for current railway stock [16] and used as input for the Swiss railway noise model SEMIBEL [17]. In 2010 another large measurement campaign was implemented as part of the sonRAIL project [18]. As can be seen from Figure 1, in the 1990s primarily passenger coaches were substantially improved, among others because cast-iron brakes were replaced by disk- brakes. A comparable positive trend can be seen for locomotives and freight wagons in the following period. Over the period under consideration, a reduction of the emission per vehicle between 10 and 15 dB can be observed.

Figure 2: Cumulative distribution of passenger train pass-by levels on both tracks of six monitoring locations across Switzerland in 2003 and 2020 (Source: [19], reproduced with permission).

2.3 Emission of commercial airplanes

The age of commercial passenger transport with jet engines began in the 1960s. The development of the turbofan engine and the continuous increase of the bypass ratio led to massive reductions in noise emission of almost 20 dB until 1980. Comparisons of certification measurements reveal that since then, further improvements have been made and that latest generation aircraft feature additional reductions in noise emission during departure of at least 5 dB (see for example chart 10

105 100 seeseeNRes e838 8 2° %

in [20]). Taking into account typical operating durations of commercial aircraft and the delay in the renewal of aircraft fleets, a comparable reduction of the average emission per aircraft as for rail vehicles can be assumed for the period under consideration.

2.4 Changes in traffic volume

In addition to the change in the emission of individual vehicles, the noise pollution is of course also depending on changes in traffic volume. Data from the Swiss Federal Statistical Office indicates that the number of passenger kilometers increased by around 25% for road traffic and by 45% for rail traffic since 1995. For air traffic, the number of passengers even increased by 145% [21]. While the number of passengers in road traffic can be regarded as constant over time, the transport performance of trains and airplanes has increased continuously. Accordingly, the growth of train and airplane movements is in reality smaller that the passenger figures suggest. Figure 3 shows aircraft noise contours of 60 dB L day for Zurich airport between 1987 und 2018. In this period, the number of flights increased from 179'163 to 264'692. This growth in volume only corresponds to an increase of the long-term average sound pressure level L eq of less than half a dB. However, the size of aircraft noise exposure contours decreased substantially, demonstrating the huge effect of quieter aircraft. The observation of shrinking aircraft noise exposure contours is ubiquitous.

Figure 3: Aircraft noise contours for the 60 dB Lday between 1987 and 2018 at Zurich Airport (ZRH) (Source: Zurich Airport AG, reproduced with permission).

3 EVIDENCE FOR INCREASING ANNOYANCE IN THE CASE OF RAILWAY AND AIRCRAFT NOISE

The figures below show exposure-annoyance curves for a range of original studies from Switzerland [3, 22, 23], from the WHO Environmental Noise Guidelines evidence review on annoyance [24] about road, rail and aircraft noise annoyance, in comparison to the respective curves from the earlier meta analyses carried out by Miedema and Oudshoorn, also known as the "EU- curves" [25]. For each curve, the respective relevant survey year(s) are indicated as well. The curves suppose a slight but not very pronounced increase in road traffic noise annoyance (Figure 4), but a marked shift towards higher annoyance for railway (Figure 5) and aircraft noise (Figure 6).

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For a constant percentage of highly annoyed, the annoyance shift corresponds to about 3-5 dB for road traffic, but 10 dB or more for rail and air traffic when comparing the EU-curves with the more recent studies.

Figure 4: Exposure-response curves for %HA from road traffic noise through the years. The survey years in which the original data for the curves were collected are indicated on the right of the plot.

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Figure 5: Exposure-response curves for %HA from railway noise through the years. The survey years in which the original data for the curves were collected are indicated on the right of the plot.

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Figure 6: Exposure-response curves for %HA from aircraft noise through the years. The survey years in which the original data for the curves were collected are indicated on the right of the plot.

= SIRENE (Bink eta) Wo Environmental Noise Guidlines (Gush etal) — Laxmstusie 2000 (Brink, With, Seer) ‘Lrmstie 80 (va & Hatenmeoser) EU (iedema-Kurve) }2014, 2015 12001-2014 !2001, 2003 1991 11965-1992 BE883 3 8 10% ee ee a ) Lon f4B(A)]

4 POTENTIAL EXPLANATIONS FOR THE OBSERVED ANNOYANCE TRENDS

There is a variety of potential reasons that could cause the observed trends of annoyance over time. The following ones will briefly be discussed: 1. Changes in research methodology (including survey methodology and method of data col- lection)

2. Changing values and attitudes in society

3. Changing semantics of words used in survey instruments

4. Changes in exposure characteristics (including source characteristics)

5. Changing (acoustical) comfort expectations

3.1 Changes in research methodology

Survey modes : While only discussed and exemplified with aircraft noise, the paper by Brooker [5] includes some potential hypotheses, which could be extrapolated to other noise sources: Studies of attitudes, such as annoyance from aircraft noise, use a variety of survey ‘modes’. These include face-to-face interviews, self-completion questionnaires sent out by post, and landline (rather than mobile) telephone surveys. The reasons for using these different modes include cost and accessibility of the target population. The implications of choosing a given mode are usually discussed in connection with each individual survey. However, what are the implications of combining the results of studies using different modes? Do face-to-face, postal and telephone surveys produce similar results if tested on the same population? If so, what are the implications for explaining the annoyance trend if the usage of the different modes changes over time? These are important questions to resolve. Annoyance measurement scales. With respect to effects of answer scales associated with the ICBEN and ISO standards [26, 27], there is evidence that numerical 11-point scales are associated with somewhat higher annoyance raw scores, as compared to verbal 5-point scores [28]. And it seems in fact, that the use of the 11-point scale has indeed increased lately (non-systematic observation for the last 10 years, but Janssen et al. stated this already in 2011 [1]. Response rate. There seems to be a general trend in social science research of dropping response rates in surveys [29]. Evidence for this trend is most compelling from long-term trend surveys that have been repeated over many years. This could explain increasing annoyance rates when a mechanism is at work that leads to more and more non-annoyed people to not take part in noise annoyance surveys (simply because they have no interest to express their voice). There is some supporting evidence for this explanation: Van Kempen and van Kamp found in their meta-analysis that surveys with high response rates reported a lower prevalence of high annoyance: when the response rate decreased, the estimated noise level (Ldn) where 25% of the respondents was highly annoyed, increased [9]. However, they found no indications for a trend of the response rate itself. Noise assessment methodology. In earlier times, noise exposure was typically measured and interpolated to assess the exposure at a specific location. Nowadays, at least for large field studies, exposure is in most if not all cases calculated. The applied calculation models and the underlying input data, as well as processor speeds, evolved over the years and the accuracy of the calculation results was raised. This might have led to varying measurement or calculation-related errors over time. Guski for example stated that "early" (1990-2008) noise calculation programs tended to overestimate certain continuous aircraft sound levels by up to 3 dB, which may have contributed to an underestimation of noise annoyance at such sound levels [2]. However, such uncertainties are primarily to be expected at lower exposure levels and are by far smaller than the observed

annoyance shifts (and hence probably negligible). In addition, many calculation models have been in use over several decades. For example, the Swiss aircraft noise studies shown in Figure 6 have all been conducted based on calculations of the model FLULA2 [30].

3.2 Changes of attitudes and values in society

Attitudinal and value changes over the years. It is sometimes heard that the population may has become more sensitive to noise in the last years. Whatever this expression may mean exactly, there is no indication in past noise surveys that noise sensitivity (as a personality trait) has increased over time. The World Values Survey [31] reports an increase in emancipative values that combine “... an emphasis on freedom of choice and equality of opportunities. Emancipative values, thus, involve priorities for lifestyle liberty, gender equality, personal autonomy and the voice of the people. ” This is of course no proof of a connection between the increase of personal autonomy and voice of the people – as stated in surveys – on one side, and the increase of noise annoyance in surveys on aircraft and railway noise at the other. It might be that the effects of an increase in personal autonomy and voice is restricted to the minority of politically active citizens, and does not carry over to annoyance judgments of many residents taking part in noise surveys. However, we cannot be sure about that at the moment and should keep this as a potential explanation, in line with earlier thoughts by Guski [2]. Also changing risk perception in the society may play a role. Back in 2004, Bröer and Wirth speculated about possible "Zeitgeist" causes for the increase in aircraft noise annoyance in the decades before [32]. Against the background of Beck's theory of "risk society" [33], they argued that the ongoing and increasing technologization of our world (in particular using aviation as an example) is less and less associated with human progress, but is increasingly perceived as threatening, which in the final analysis would then also be reflected in intensified annoyance responses regarding aircraft noise. From the point of view of Beck's considerations, political distrust, pessimism about technology, and maybe also a more profound ecological sensibility that developed over the years are important non-acoustic factors mediating or moderating noise annoyance today. All these attempts at explanation seem plausible, but are not (yet) supported by data. And last but not least, the theory does not explain the increase in railway noise annoyance, given the idea that railways are widely regarded as a safe and ecological means of transport. A lifestyle of health and sustainability has become highly popular in the last decade. The study "Umweltbewusstsein in Deutschland 2020 (environmental awareness in Germany 2020)" [34] indeed showed that over the years, the German population has become increasingly aware of the negative health effects of environmental pollution. Accordingly, more and more Germans perceive a burden from environmental pollutants – the figure has risen by 15 percentage points since 2000 and is just under 40% in 2020. Whereas 20 years ago about 25% of respondents stated that they were not at all affected by environmental factors, the corresponding figure dropped to only 7% in 2020 (page 31). Support for this explanation also comes from the World Values Survey [31]. It seems obvious that a growing awareness of the health risks of noise exposure goes hand in hand with a decreasing willingness to tolerate corresponding exposures – and hence an increase in the percentage of people considering themselves as highly annoyed by noise.

3.3 Changing semantics of words

Do the words to express the intensity of one's noise annoyance used in questionnaires in socio- acoustic surveys still mean the same as they did several decades ago? Does e.g. the notion of "extremely annoyed" express the same degree of annoyance nowadays than in the past? That the observed annoyance trend could in fact just be a trend of a shift in meaning is an explanation that Guski brought up on the occasion of his keynote lecture at the ICBEN 2017 in Zurich [2]. Maybe we encounter here – as echoed for example in the drifting apart of political views and the

concentration of opinions at the poles almost everywhere on the political landscape – a kind of "extremization", i.e. the tendency to more easily express one's feelings at the extreme ends of a (annoyance) scale, with the consequence of more highly annoyed people at a given exposure level.

3.4 Changes in exposure characteristics

An often discussed potential reason for increasing aircraft noise annoyance over the last decades is the increased number of movements along with a less noisy fleet mix. Today, an acoustic annual average noise level is – at least for rail and air traffic – composed of considerably more individual noise events with lower emissions. Thus, the (increasing) number of events is often seen as a possible or likely cause for the annoyance trend because it is the most obvious change in exposure characteristics. Haubrich et al. reevaluated existing German and Swiss survey data for aircraft noise to elucidate the role of the number of events on annoyance. They indeed found that statistical models that incorporate a number of events-like predictor (e.g. NATx) in addition to an energy- based predictor yielded higher explained variance and showed a statistically significant effect of the NAT predictor on annoyance [35]. However, their results were not in all cases consistent. It seems to us that the increasing number of movements alone cannot fully explain the observed annoyance trend. Here, the question arises whether the same single events are evaluated differently today than in the past, or whether those affected by aircraft noise have noticed (a) the reduction in maximum levels and (b) the increase in the number of events, and if so, how these experiences are incorporated into their summary judgment of annoyance.

3.5 Changing (acoustical) comfort expectations

We noticed that especially for the two types of noise where the progress in reduction of emission levels has been particularly great – namely railway and aircraft noise – people have become more and more annoyed over time at a given exposure level. The situation is quite different for road traffic noise: the roads that have been loud in the past are – in most cases – still loud today. For road traffic noise, there was even a (small) net increase of noise exposure in the last decades. In contrast to that noise source, aircraft and railway noise mitigation was much more successful, resulting in a considerable overall reduction of noise exposure for these sources (as for example demonstrated in Figure 3). It seems that for these sources the annoyance (of an average person living at a certain place) remained the same , while the exposure was reduced . Thus it might be a good idea to try to explain the annoyance trend by focusing on the trend of exposure and the differences of this trend between the sources. An analogy from happiness research may serve as a starting point: Interestingly, subjective happiness is not depending on the absolute amount of household wealth, but it is depending on the individual's wealth relative to the wealth of the immediate social environment (see for example [36]). The estimation of one's subjective well-being is not a function of absolute wealth, but is formed when individuals compare themselves with others, e.g. their neighbors. A similar mechanism might be at work with noise pollution (or the reduction thereof): One's individual annoyance assessment only reflects the ranking of one's own exposure at home in comparison with other exposure situations one is familiar with. Consequently, if noise abatement measures (at the source) lead to a reduction of the overall exposure, this does not affect one's individual ranking within, e.g. – a neighborhood, and consequently does not lead to a change in the annoyance rating. Of course, this applies only to slow changes in exposure, as it is the case for gradual transformations of a vehicle fleet for example. In addition, it is an everyday observation that people adapt extremely quickly to a more comfortable life, whereas losses of comfort are perceived as much harder to bear. Being protected from noise is of course more comfortable than being exposed to noise. With ever better sound insulation of dwellings, lower emissions of vehicles, in particular trains and aircraft, the frame of reference about

what is tolerable could shift over time. Another analogy: Nowadays, at least in European countries, entire apartments are heated up to maybe 22 degrees Celsius or so during the wintertime, which can be considered a "norm" nowadays, whereas just one or two generations earlier, many homes did not even have central heating and maybe only one room was heated at all. Hence, typical conditions of these days would today be considered as being unbearable. A similar mechanism could be responsible for the observation that people nowadays seem to react more sensibly to noise levels that were previously tolerated. As the emissions from and exposure to railway and air traffic dropped considerably in the last decades, a corresponding change of frame of reference may specifically affected the shift of the exposure-response relationships of these two sources – whereas both road traffic noise exposure and road traffic noise annoyance remained stable over the last decades.

4 CONCLUSIONS

From the potential explanations for the observed annoyance trend that we discussed in the previous sections, some could explain the smaller or larger increase of noise annoyance, independent of the type of noise source. In our view, comfort expectations and a lifestyle of health and sustainability in combination with a growing awareness of the health risks of noise seem most plausible to explain the slight annoyance shift that is visible for all three traffic noise sources. However, the strong additional annoyance shift that shows up for railway and air traffic noise cannot be explained this way. As the hypothesis of changing exposure characteristics could not be confirmed, we suspect a "frame of reference problem" and speculate that the successful noise abatement at the source could itself be the cause of rising comfort expectations and thus stable annoyance even if the exposure levels decreased. As we can see, the reduction of the average sound emissions for rail and air traffic is in the same order of magnitude as the shifted exposure-annoyance curves (as they are for example visible in Figures 5 and 6). In other words, it looks as if the railway and aircraft noise annoyance ratings of the population remained widely constant over time, while the underlying exposure changed. The general trend towards higher annoyance at a given exposure level whose reasons we speculated about could have consequences for the future of noise regulation and, particularly, the setting of noise exposure limits. If all the successes in noise abatement are not able to reduce overall noise annoyance in the population (because the frame of reference has changed or because of increasing comfort expectations or similar trends), this would confront the legislator with the question of whether it is rightful to continue to lower limit values in order to meet the population's increased expectations of less noise. And, if, obviously – the relation between the noise exposure reduction and annoyance reduction is that weak, is the lowering of noise limits an appropriate means to reduce the population's annoyance? One potential way out of this could be to abandon annoyance (e.g. objectified as percentage highly annoyed) as the defining criterion for setting limit values and to focus on more "stable over time" outcomes, e.g. cardiometabolic risks. In order to empirically verify the upward annoyance trend (and to end the debate about whether it exists or not) for both aircraft and railway noise, noise effects researchers must carry out pooled analyses of systematically collected original survey data over longer periods of time and also focus on the temporal trend of noise sensitivity (as a stable personality trait), not just on the temporal trend of noise annoyance. One important resource that could help to reach this goal will be ICBEN's archive of original noise reaction survey data, which is currently under development, and which should, in a first version, see the light of day very soon.

5 ACKNOWLEDGEMENTS

Supported by institutional funds of Empa and the Federal Office for the Environment. The authors deny any conflicts of interest related to this paper.

6 REFERENCES

1. Janssen, S.A., et al., Trends in aircraft noise annoyance: The role of study and sample characteristics. Journal of the Acoustical Society of America, 2011. 129 (4): p. 1953-1962. 2. Guski, R., The increase of aircraft noise annoyance in communities: Causes and consequences , in 12th ICBEN Congress on Noise as a Public Health Problem . 2017: Zurich. 3. Brink, M., et al., A survey on exposure-response relationships for road, rail, and aircraft noise annoyance: Differences between continuous and intermittent noise. Environment International, 2019. 125 : p. 277-290. 4. Gjestland, T., On the Temporal Stability of People's Annoyance with Road Traffic Noise. Int J Environ Res Public Health, 2020. 17 (4). 5. Brooker, P.I., Do people react more strongly to aircraft noise today than in the past. Applied Acoustics, 2009. 70 : p. 747-752. 6. Gjestland, T., Recent World Health Organization regulatory recommendations are not supported by existing evidence. The Journal of the Acoustical Society of America, 2020. 148 (2): p. 511-517. 7. Brink, M., Comment on ‘Recent World Health Organization regulatory recommendations are not supported by existing evidence’ [J. Acoust. Soc. Am. 148, 3397–3398 (2020)]. Journal of the Acoustical Society of America, 2021. 149 (1967): p. 3397-3398. 8. Gjestland, T., Response to “Comment on ‘Recent World Health Organization regulatory recommendations are not supported by existing evidence’ ” [J. Acoust. Soc. Am. 148, 3397–3398 (2020)] (L). Journal of the Acoustical Society of America, 2021. 149 (3): p. 1967- 1968. 9. van Kempen, E.E. and I. van Kamp, Annoyance from air traffic noise. Possible trends in exposure-response relationships (Report01/2005 MGO EvK) . 2005, Dutch Ministry of Housing and Environmental and Spatial Planning: Bilthoven. 10. Federal Office for the Environment FOEN, Umweltbelastungen des alpenquerenden Güterverkehrs, Stand 2015 , in Resultate des Projekts MFM-U , Federal Office for the Environment FOEN, Editor. 2016, Federal Office for the Environment FOEN,: Bern. p. 22. 11. Hammer, E. and E. Bühlmann, Veränderung der Lärmemissionen von Fahrzeugen auf Schweizer Strassen , G.P. Ingenieure, Editor. 2018. p. 28. 12. Federal Office for the Environment FOEN, Computermodell zur Berechnung von Strassenlaerm, Teil 1, Bedienungsanleitung zum Computerprogramm StL-86 , in Schriftenreihe Umweltschutz . 1987, Bundesamt für Umwelt, Wald und Landschaft, Schweiz. p. 47 ff. 13. Heutschi, K., SonRoad: New Swiss road traffic noise model. Acta Acustica United with Acustica, 2004. 90 (3): p. 548-554. 14. Heutschi, K., B. Locher, and M. Gerber, sonROAD18: Swiss Implementation of the CNOSSOS-EU Road Traffic Noise Emission Model. Acta Acustica united with Acustica, 2018. 104 (4): p. 697-706. 15. Hofmann, R. and A. Rosenheck, Berechnungsmodell fuer Eisenbahnlaerm . 1978, Eidg. Materialprüfungs- und Versuchsanstalt Empa: Dübendorf, Switzerland. p. 43 (+ Annex). 16. Grolimund & Petermann, Berechnungsmodell Eisenbahnlärm - Untersuchung der emissionsbestimmenden Parameter - Neuer Emissionsansatz , Z.f.L. Baudirektion SBB, Editor. 1990, Baudirektion SBB, Zentralstelle für Lärmfragen. p. 39 (+ Annex). 17. Federal Office for the Environment FOEN, SEMIBEL: Schweizerisches Emissions- und Immissionsmodell für die Berechnung von Eisenbahnlaerm , S.F.O.f.t. Environment, Editor. 1990, Swiss Federal Office for the Environment. 18. Thron, T. and M. Hecht, The sonRAIL emission model for railway noise in Switzerland. Acta Acustica United with Acustica, 2010. 96 : p. 873-883.

19. Federal Office of Transport FOT, Monitoring Eisenbahnlärm, Jahresbericht 2020 , in Monitoring Eisenbahnlärm , Federal Office of Transport FOT, Editor. 2020, Monitoring Eisenbahnlärm: Bern. p. 40. 20. International Air Transport Association IATA, Vision 2050 , G. Bisignani, Editor. 2011, International Air Transport Association - IATA Singapore. p. 87. 21. Federal Statistical Office FSO, 2021Mobilität und Verkehr,Taschenstatistik 2021 , Federal Statistical Office FSO, Editor. 2022, Federal Statistical Office FSO,: Bern. p. 10. 22. Brink, M., et al., Annoyance responses to stable and changing aircraft noise exposure. Journal of the Acoustical Society of America, 2008. 124 (5): p. 2930-2941. 23. Oliva, C., Belastungen der Bevölkerung durch Flug- und Strassenlärm . 1998, Berlin: Duncker&Humblot. 24. Guski, R., D. Schreckenberg, and R. Schuemer, WHO Environmental Noise Guidelines for the European Region: A Systematic Review on Environmental Noise and Annoyance. International Journal of Environmental Research and Public Health, 2017. 14 (12): p. 1539. 25. Miedema, H. and C. Oudshoorn, Annoyance from transportation noise: Relationships with exposure metrics DNL and DENL and their confidence intervals. Environmental Health Perspectives, 2001. 109 (4): p. 409-416. 26. ISO/IEC, ISO/TS 15666:2021 Acoustics -- Assessment of noise annoyance by means of social and socio-acoustic surveys . 2021. 27. Fields, J.M., et al., STANDARDIZED GENERAL-PURPOSE NOISE REACTION QUESTIONS FOR COMMUNITY NOISE SURVEYS: RESEARCH AND A RECOMMENDATION. Journal of Sound and Vibration, 2001. 242 (4): p. 641-679. 28. Brink, M., et al., Effects of Scale, Question Location, Order of Response Alternatives, and Season on Self-Reported Noise Annoyance Using ICBEN Scales: A Field Experiment. Int J Environ Res Public Health, 2016. 13 (11). 29. Stedman, R.C., et al., The End of the (Research) World As We Know It? Understanding and Coping With Declining Response Rates to Mail Surveys. Society & Natural Resources, 2019. 32 (10): p. 1139-1154. 30. Thomann, G. and R. Bütikofer, FLULA2: Aircraft noise prediction and measurements. The Journal of the Acoustical Society of America, 1999. 105 (2): p. 1065-1065. 31. The WORLD VALUES SURVEY ASSOCIATION. World Values Survey . 2022; Available from: https://www.worldvaluessurvey.org. 32. Bröer, C. and K. Wirth, Mehr Belästigung bei gleichem Pegel. Wieso Flugzeuggeräusche heute möglicherweise lästiger sind als vor 40 Jahren. Zeitschrift für Lärmbekämpfung, 2004. 51 (4): p. 118-121. 33. Beck, U., Risk society, towards a new modernity . 1992, London: Sage. 34. BMUV/UBA, Umweltbewusstsein in Deutschland 2020 - Ergebnisse einer repräsentativen Bevölkerungsumfrage [Environmental Awareness in Germany 2020 - Results of a Representative Population Survey] . 2022, BMUV/UBA. 35. Haubrich, J., et al. Leq + X: Re-Assessment of exposure-response relationships for aircraft noise annoyance and disturbance to improve explained variance . in 23rd International Congress on Acoustics 2019. Aachen (Germany). 36. Senik, C., Wealth and happiness. Oxford Review of Economic Policy, 2014. 30 (1): p. 92- 108.