Viewing the changes in community annoyance due to aircraft noise over the times Ichiro Yamada 1 RION CO. Ltd. 3-20-41 Higashimotomachi, Kokubunji, Tokyo 185-8533. Japan

ABSTRACT More than 60 years have passed since the introduction of jet aircraft to civil aviation, and technological innovations have made aircraft much quieter. Nevertheless, people still complain that they experience severe suffering from aircraft noise. The changes in lifestyles, values concerning the sound environment, and aircraft operating conditions including the air traffic control system, over time, may have influenced the differences in annoyance responses. This paper overviews and considers the changes over time in the aircraft sound exposure level around the airport and the community annoyance caused by aircraft noise. Then it discusses the issue of recent noise complaints associated with the introduction of new air traffic management systems and flight routes as well as views the impact of coronavirus pandemic over the last two years or longer. Finally, it gives a minor consideration to how we should deal with these changes in the annoyance response.

1. INTRODUCTION

Community annoyance with aircraft noise is said to have become more severe since the turn of the century, although, in contrast, no apparent change exists in the annoyance with road traffic noise 1, 2) . There must be causes specific for the former. Despite civil aircraft having become much quieter, concerns about aircraft noise have intensified. The question of what caused such an unexpected reality led us to consider a few issues, such as the trend of low-noise aircraft in service, changes over time in aircraft sound exposure, and in community annoyance with aircraft noise. We also discuss a recent issue of noise complaints associated with the new air traffic management system, such as area navigation. Since spring 2020, the world has been amid the pandemic of coronavirus infections for more than two years, which has severely impacted all aspects of our social life. Air transportation is no exception, with a sharp decline in flight operations, which has brought positive improvements to the sound environment around the airport but has severely impacted society and the economy. While we expect the pandemic will eventually end and air traffic will return to and even exceed previous situations, its impact may bring about more than transitory changes in our lifestyles and the way of air traveling and transportation. Assuming such a future outlook, this paper reviews and discusses the differences in community annoyance with aircraft noise over time, based on the situation of air traffic before the pandemic outbreak. Next, we look at the impact of the pandemic on noise exposure and community annoyance around airports. Finally, it discusses future trends in community annoyance with aircraft noise and how to manage it.

1 i-yamada@rion.co.jp

2. AIRCRAFT NOISE REDUCTION AND ANNOYANCE CHANGE

2.1. Progress in aircraft noise reduction at the source Civil aircraft have made significant progress in noise reduction owing to the introduction of the noise certification process 3) . Figure 1 shows the trend of certification noise levels for the fly-over and landing certification points by aircraft type and year of service over the past 60 years. The certification noise level has been 15-20 dB lowered, compared with the 1960s, as the year of service gets newer. Looking at the figure, we can guess the average rate of noise decrease at the source is roughly 0.2~0.3 dB/year for each certification point. We can estimate the rate as 0.25 (~ 33/45) dB/year/point if we calculate it using the yearly trend of cumulative margin values relative to Chapter 3 over 45 year period between the applicable years of 1972/Chapter 2 and 2017/Chapter 14 for the three certification points (fly-over, approach, and sideline) 4) . The rate becomes 0.21 (~35/55/3) dB/year/point if we do it referring to a similar plot of the trend of cumulative margin values relative to Chapter 4 over 55 years 5) . Note that the certification noise levels of civil aircraft seem to have decreased sharply by more than 10 dB when the noise certification standard transitioned from Chapter-2 to Chapter-3 5) .

Certification noise level in EPN dB

FO

LD

Age of service

1990s

2000

2010s

1970s

1980s

~1960s

Figure 1: The relationship of certification noise levels with the year of service for different types of civil aircraft, depicted using data by ICAO et al.: blue dots are results at Fly-over certification point, whereas red dots are those at Landing certification point.

The noise reduction of aircraft was also examined from the decrease of noise levels observed at an unattended noise monitoring site, 7 km distant from the runway end at a major international airport Narita in Japan. We compared the distribution of maximum sound pressure levels L ASmax of aircraft noise events observed over a week at the same time of the year between two years 1979 and 2014. Figure 2 shows the result: left figure (a) shows a superposition of level distributions by the time of day and right figure (b) shows a superposition of frequency distributions. In 1979 there were some observations higher than 90 dB, while in 2014 all observations were lower than 85 dB. As a result, the maximum sound pressure levels experienced at the site in 2014 were 9~10 dB lower than those in 1979, although the number of observations doubled. This result suggests that the rate of noise decreases actually observed is guessed as 0.25~0.29 dB/year, which almost coincides with the average rate of noise decreases at the source.

Figure 3 illustrates the annual change in the number of flight operations by aircraft type at Narita over 40 years after the start of the airport in service. In 1979, high-noise aircraft of DC-8, B707, B747-100, etc. (turbojet and low-bypass turbofan) operated in similar proportions, but the high- noise turbojet aircraft were retired by 1990. Low-bypass turbofan aircraft were also retired from 2000 to 2010. In 2014, flight operations of small and quiet aircraft such as A320 became the most

(a) Scatterplot comparison of L ASmax observations over one week between 1979 ( The year following the airport opening ) and 2014 ( gray ).

(b) Histogram comparison of L ASmax observa-

tions between 1979 ( red ) and 2014 ( gray ).

One week in NOV. 2014 ( Gray dots: 1405 event data )

One week in NOV. 1979 ( Red dots: 654 event data )

1979

2014

Frequency per day

L ASmax in dB

Higher than

double

1979

9-10dB

2014

Time in hour

L ASmax values in dB

Figure 2: Comparison of L ASmax observations between 1979 ( red ) and 2014( gray ). Data

were observations at a site 7km distant from the runway end under the flight path over one week in November both in 1979 and in 2014.

(a) Level distributions of L ASmax observations by time of day over one week. (b) Frequency distributions of L ASmax observations.

Number of flight operations per aircraft type

Start of using B-runway

(April 2002)

Prohibition of Chapter 2

aircraft in Japan

Prohibition of the operation of older, high noise aircraft

Year

40

2 0

60

30

50

Age of people who were adults at the time of 2014.

Figure 3: Change in annual number of flights by aircraft type at Narita Airport 6) .

common at Narita. We guess that large airports in Japan have experienced a generational change in the aircraft fleet and that the situation of aircraft noise observed has shifted from ‘high noise but low frequency’ to ‘low noise but highly frequent’ around the turn of the century in Japan.

The horizontal scale depicted at the bottom of Figure 3 shows the years when people 20-60 years old in 2015 had been 20 years old: e.g., people aged 50 in 2015 had been 20 years old in 1985. We will refer to a social survey carried out at Narita in 2016 (NRT-2016) in clause 2.2. The age of respondents who participated in that survey was distributed between 20 and 70 years old, but the majority were under 50. We can guess that a major part of respondents rarely experienced the sound of high noise aircraft such as DC-8 and B707.

The introduction of low-noise aircraft also brought about changes in sound characteristics. In the sound of early turbojet aircraft, the contribution of broadband noise due to high-speed jet exhaust was dominant and was very noisy as a roaring sound. With the introduction of turbofan engines, tonal sound due to the rotation of large-diameter fan blades became superior as the bypass ratio became higher and the sound quality of aircraft noise became softer but annoying. Such changes in the noise characteristics are also considered to have affected noise annoyance.

2.2. Changes of community annoyance with aircraft noise over survey ages Despite the progress in aircraft noise reduction at the source, shown in clause 2.1, community annoyance with aircraft noise is said to have become more severe. According to ISO 1996-1, the prevalence of high annoyance with aircraft noise in social surveys shows a small increase of about 0.2 dB per year from about 1960 to 2005 for a total change of almost 10 dB 7) . The new WHO European Noise Guidelines:2018 2) , based on the results of social surveys conducted since the beginning of this century (2001-2011 for aircraft), found that the annoyance response is the same as before for road noise, but has become more severe for aircraft noise, and proposed setting the guideline value for aircraft noise to 45dB, which is severer by 10 dB than the previous one 3) . The situation in the US is similar: According to FAA, annoyance response to aircraft noise has become much more severe compared with the one shown in FICON-1992 8) , based on social surveys carried out in 2015-2016 at 20 airports across the U.S.

Figure 4 shows a comparison of eight dose-response curves of social surveys: Among those, four curves depicted as solid lines are results of meta-analyses of multiple surveys obtained in the US and Europe: FICON-1992 8) , TNO-2001 9) , WHO-2018 2) and FAA-2021 10,11,12) . The other four depicted as dotted lines are results of social surveys carried out in Japan 13) : JPN24-1996 (Osaka in 1996) 14) , JPN19-2003/6 (Haneda et al. in 2003~2006) 15) , JPN23-2006 (Kumamoto in 2006) 16) and NRT-2016 (Narita in 2015) 17) . The figures may be somewhat inaccurate because they are plotted by reading the response rate in %Highly-Annoyed from literature and ignoring the difference between L dn and L den .

Keeping this in mind, we first compared the four curves of meta-analysis. We can find there is a clear difference in response rates between FICON-1992 and the other two WHO-2018 and FAA- 2021 with the latter being higher. TNO-2001, which is based on surveys conducted before 2000, lies slightly higher in response rate than FICON. Next, comparing the four Japanese curves of single surveys with those of the meta-analysis, three curves (JPN19-2003/6, JPN23-2006 and NRT- 2016) of surveys conducted after 2000 have response rates as high as WHO-2018 and FAA-2021. On the other hand, the response rate of the curve of one survey before 2000 remains comparable to FICON-1992 and TNO-2001, except for one point at an extremely high level of sound exposure. From this discussion, we can guess that there is a clear difference in the response rate of dose- response curves before and after the turn of the century, with annoyance responses being much higher in this century. Comparing average sound exposure levels at a 20% response rate, the average of five curves after the turn of the century is roughly 50 dB, whereas the average of three

0 10 20 30 40 50 60 70 80 90 100

Response in %Highly-Annoyed

FAA-2021

WHO-2018

JPN19-2003/6

JPN23-2006

TNO-2001

FICON-1992

JPN24-1996

NRT-2016

35 45 55 65 75 85

Average sound exposure evaluated by L dn or L den and expressed in dB

TNO-2001 WHO-2018 FICON-1992 FAA-2021 NRT-2016 JPN24-1996 JPN23-2006 JPN19-2003/6

Figure 4: Comparison of dose-response curves for aircraft noise among the various social survey results

2,9,10,13) . Solid lines are results obtained from meta-analysis, whereas dashed lines are results obtained from a single survey in Japan.

curves before the turn of the century is about 65 dB, and the difference is 15 dB. If we take a 30% response rate, the result becomes 55 dB and 69 dB, resulting in a difference of 14 dB. Anyway, this result suggests that the annoyance response to aircraft noise has become about 14~15 dB more severe in Europe, the US, and Japan after the turn of the century. It is not certain whether it harmonizes with the ISO 1996-1 suggestion of a gradual increase in the prevalence of high annoyance of about 0.2 dB per year, but this author expects that the phase-out of high noise turbojet and low-bypass turbofan Chapter-2 aircraft may have to do with the large difference in the rate of %Highly-Annoyed with aircraft noise during the turn of the century, at least in Japan. Anyway, considering the high progress in aircraft noise reduction at the source, we cannot help but be surprised at the strong intensification of the response.

Such intensification of community annoyance response to aircraft noise may be the result of a combination of various causes. One cause may be that people are now demanding a higher grade for the sound environment as an important element of their quality of life. Another cause may be the change in resident generations over the years may be also an important cause: In recent surveys, the majority of respondents consists of people who never experienced the intense aircraft noise of the early-age high noise aircraft. As mentioned earlier, early-age high-noise aircraft stopped flying in Japan by around 1990, and Chapter-2 aircraft were phased out by 2002. It is difficult to argue with the evidence, but if we feel aircraft noise, which rises up to the upper limit of the level range which we usually experience in everyday life, to be very noisy, it is perhaps not surprising that the annoyance response has become more severe over time.

3. NOISE COMPLAINTS AND ANNOYANCE DUE TO THE INTRODUCTION OF NEW

FLIGHT PATHS AND NEW AIR TRAFFIC MANAGEMENT SYSTEMS

In Japan, in order to expand air traffic capacity in the Tokyo metropolitan area, new air traffic management systems have been introduced and new takeoff and landing routes have been established to fly over urban areas. As part of this effort, wide-area navigation (RNAV) was introduced about a decade ago in the metropolitan area, and aircraft began to fly without deviating from the specified routes connecting designated points. As a result, at Tokyo International (Haneda) Airport, aircraft heading for the runway from the north began to fly every few minutes over specific regions of Chiba City along certain fixed routes in southerly winds and good weather, and people living in the regions became forced to experience the sound of aircraft flyover at a rate of high frequency, although not at a high level. It became a severe problem of noise nuisance 18,19) . Before the introduction of RNAV, aircraft flew at lower altitudes and louder, but their flight routes highly scattered because flights were controlled by radar vectors, and so noise complaints had occurred less frequently. However, as the mayor of the local government admitted that the noise of aircraft flying by RNAV was unbearable, so the sound was transformed into ‘extreme noise nuisance.’ A few years later, it seems that similar noise issues occurred in Europe and the US. Since these problems usually occur outside of noise control zones, it is difficult to take measures such as soundproofing subsidies based on the law. Here we examine the situation after a few more years have passed.

3.1. Recent situations of noise issues around the metropolitan airports in Japan At the end of March 2020, Haneda Airport began operating a new flight route over the city center of Tokyo, although the use of the new route was limited to only four hours in the afternoon in southerly winds and good weather. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) had repeatedly held briefings for residents over several years to explain the operational procedures, noise mitigation measures and damage compensation, to seek their understanding. Besides, flight operations were reduced due to the coronavirus pandemic. Nevertheless, residents living along the route voiced concerns about a risk of noise impact and damage by object falling when aircraft fly and gradually lower altitude over the city center. In June 2020, residents living along the route filed a class action lawsuit. The complaint, however, only refers to the damage as ‘various types of damage to people's lives caused by noise from aircraft,’ but it mentions nothing

about specific details of the damage. Afterwards, the MLIT decided to establish a study group to discuss how to avoid fixing the flight route, although it is unclear whether it has something to do with the lawsuit. The group met four times to examine whether there are any measures that could be reviewed from the perspective of noise abatement, etc., by August of that year 20,21) . As far as looking at the published material, it is not clear whether they have estimated how much noise reduction can be expected, although they looked into various RNAV methods. After the start of using the new path, residents living under the conventional approach route on the Chiba side seem to continue to complain about noise damage. Thus, it is not clear from the online information whether the addition of the new route contributes to the reduction of damage to the residents under the conventional route.

Next, Narita Airport is also underway for expanding its air traffic capacity by extending operating hours, expanding the second runway, and constructing a third runway. The airport operation hours were extended by one hour to midnight in the winter timetable that began at the end of October 2019. The number of night flight operations is gradually increasing, but there have been no severe complaints due to the extension of operating hours, as far as online information is concerned, perhaps because the total flight operations has been drastically reduced by the pandemic.

3.2. Noise issues due to new air traffic management systems in other countries Introducing a new air traffic management system or new flight routes may cause severe noise issues. In 2007, the US began transitioning to a new air traffic management system NextGen based on wide-area navigation (PBN) as a solution to the long-standing problem of congestion delays in air traffic 22) . PBN allows aircraft to fly precisely over designated points, so noise damage can be minimized by avoiding densely populated areas and setting routes. However, when PBN operations began at Metroplex initiatives in the mid-2010s, severe noise problems began to occur in areas more than 20 to 30 km away from the airport and under the route. This seems to be a major problem at more than 9 Metroplexes 23,24) , although the adoption of PBN was supposed to concentrate routes and minimize noise impact areas. The frequency of noise events has increased in areas directly under the routes, causing unprecedented opposition. A blogger wrote, ‘The annoyance of aircraft noise, as if it were a continuous hissing or wailing, cannot be quantified by measurement, and can only be assessed qualitatively, but the severity of the response is not negligible 23) .’ A subsequent search of online information on this issue revealed an article in the JDA Journal 24) . This article reiterates the list of metropolitan areas where PBN noise is a problem and recommends that the situation in the complaint area directly under the PBN path be closely examined. The Washington Post says 25) ; ‘It's unprecedented noise pollution from NextGen. The problem seems to be still unresolved 26,27) .’ Such situations may have been reflected in the severity of the annoyance response to the FAA's social survey.

Around 2014, the UK also tried to increase airport capacity by adopting wide-area navigation (PBN) at airports in the metropolitan area, including Heathrow and Gatwick, to improve efficiency through route concentration under international cooperation, and to reduce noise impact by using respite directly under the routes. The residents' group (located between Heathrow and Gatwick), which had opposed the introduction of PBN, pointed out that ‘the PBN was implemented without prior consideration of the noise impact and without consultation with the concerned community 26) .’ According to this online information, the UK Ministry of Transport and the Civil Aviation Authority were aiming to review the airspace change process in 2017 to pave the way for PBN deployment, despite the many complaints and protests against the initial trials of the PBN, and residents' groups are expressing alarm.

4. IMPACT OF CORONAVIRUS PANDEMIC ON AIRCRAFT NOISE EXPOSURE

The worldwide pandemic of the new coronavirus infection (COVID-19) that broke out early 2020 has had a serious impact on our life and economic activities. Air traffic is no exception, with passenger transport being particularly hard hit. However, in terms of noise exposure associated with

aircraft operations, the reduction in the number of flight operations has the added benefit of restoring natural quiet.

Figure 5 is a result of comparison of history records of monthly total of flight operation numbers from January 2019 to June 2021 at four Japanese (dotted lines) and at three overseas airports (solid lines): The Japanese airports are Narita/NRT, Kansai/KIX, Osaka/ITM, and Fukuoka/FUK, whereas the overseas are Sydney/SYD, New York/JFK, and Heathrow/FRA. The counts of monthly total numbers are normalized as percent rates (%) relative to the annual average of monthly total numbers in 2019.

As you see from the figure, the overseas airports experienced a sharp decline in March 2020, dropping to around 10% in April and then gradually recovered since June, returning to over 60% before summer last year at JFK and SYD. Japanese airports NRT and KIX also experienced a sharp decline in March, but only down to 30-40%, and recovery since then is a bit slower, compared with SYD and JFK. On the other hand, ITM and FUK, as having a large number of domestic flights, the decline was rather moderate, down to 30-40% in April-May and afterwards varied widely in response to the emergency declaration by the government.

Change of monthly total of flight operations in 2020 relative to the average value in 2019 (%)

10 11 12

1 2 3 4 5 6 2 0 2 1

10 11 12

1 2 3 4 5 6 7 8 9 2 0 2 0

1 2 3 4 5 6 7 8 9 2 0 1 9

Figure 5: Comparison of the monthly total of flight operations before and after the outbreak of the coronavirus pandemic. The figure shows records at seven airports (SYD/Sydney, JFK/John F. Kennedy, LHR/Heathrow, NRT/Narita, KIX/Kansai, ITM/Osaka, and FUK/Fukuoka) from January 2019 to July 2021.

Change of L den,year around Narita Airport

Change of L den,year around Osaka Airport

Noise monitors located near A-runway

Noise monitors located near B-runway

Kouda kaikan

Kushiro

Kitano

Hanshin

Arami Nakadai 34R

16R NishiOsuka Chida

Tokura

34L 16L

Annaka

Kema

Hohan

Harada

Figure 6: History records of yearly-average sound pressure level ( L den,year ) by year for Osaka Airport (left) and Narita Airport (right), based on results of unattended noise monitoring 29,30) .

Such a decline in flight operation numbers, of course, resulted in a decrease in noise exposure. Figure 6 shows history records of yearly-average sound pressure level L den , year by year over a period of 2013-2020, calculated from observations of unattended noise monitoring in the vicinity of two Japanese airports Osaka/ITM and Narita/NRT.

The left graph in Figure 6 shows historical records of L den,year for Osaka. We can see a level decrease of about 3 dB from 2019 to 2020. Another history records of monthly average L den,month in 2020 at Osaka, not included in this paper, shows that May decreased to a level about 8 dB lower than that before the coronavirus outbreak. As the monthly number of flight operations in May was 40% of the previous year-average, we can conclude that the level down was lower than expected. Note that the average decrease of sound pressure levels in 2020 among 27 stations around 10 major airports in Japan also showed a decrease of about 3 dB.

The right graph in Figure 6 shows historical records of L den,year from 2013 to 2020 at Narita. It shows a decrease of 0.6 dB on the A runway side of the two parallel runways and 7.5 dB on the B runway side, which was different from other airports. The reason for this we guess is that Runway B was out of operation from April to July 2020, immediately after the outbreak of the pandemic. On the other hand, the number of cargo flights increased compared to previous years, and as a result the number of flight operations stopped falling at the level of roughly 30% of the average number in 2019 as shown in Figure 5, and it then gradually increased thereafter. Therefore, unlike other airports, the noise level on the A runway side at Narita was about the same as in previous years, while the noise level on the B runway side decreased significantly.

In summary, noise exposure in 2020 in the vicinity of domestic airports other than Narita was 3 dB lower than in previous years due to the pandemic. The decrease in the number of flights directly translates into a decrease in noise exposure. A "3dB decrease" is a change that is clearly perceptible to our senses. Residents in the vicinity of the airport, despite the fear of a coronavirus pandemic, may feel that 2020 was a quieter year than usual in terms of both the frequency of aircraft flight operations and the reduction in sound exposure level.

Concerning situations at overseas airports, it was not possible to find similar history records of sound pressure levels on the internet, but we found a blog post by a member of the British House of Commons described the situation in London 31) : it says, ‘While the lockdown against the coronavirus pandemic was certainly a frightening experience, it was an unexpected benefit to the residents of my constituency. The district is located directly under the flight routes to Heathrow and London City, and the closure of international flight operations meant that people were freed from the horrors of night flights and their sleep improved. People's mental health also improved.’

As shown in Figure 5, Heathrow saw a 10% reduction in the number of flight operations in April 2020 and remained at 30-40% since then. This area is 27 km east of Heathrow and 6 km southwest of the city, where aircraft approaching Heathrow from the east come from the north and south and meet overhead for final approach. When the number of daily overflights was reduced from 800 per day to 80 in April 2020, inhabitants must have felt that the airspace has become much quieter!

The International Air Transport Association (IATA) and Tourism Economics released a forecast for post-Corona passenger demand recovery in May of this year 32) . According to the forecast, passenger demand will recover to 52% of the pre-corona pandemic level in 2019 this year, 88% next year, and 5% above the pre-corona level the year after, and passenger traffic in 2030 is expected to increase to 5.6 billion passengers. This figure is about 7% below the 2030 passenger volume projected before the corona pandemic, which means that the pandemic has been revised to lose two to three years' worth of growth. This is believed to be due to a decline in demand for business travel, etc., as new lifestyles and business styles, such as the establishment of remote work, become more prevalent. How will the aircraft noise annoyance response change with these changes in flight operations and lifestyles in the future? 5. DISCUSSION OF CHANGE IN AIRCRAFT NOISE ANNOYANCE

The coronavirus pandemic has brought an unexpectedly quiet sound environment to the area surrounding the airport. However, the pandemic will be overcome within a few years, and air traffic

is expected to eventually return to and exceed previous levels, even in an era of global warming and SDGs initiatives. We will experience a swing back from a short-term quiet sound environment to a noisy sound environment. What effect will this have on the annoyance response?

With the introduction of wide-area navigation in Japan, the U.S., and Europe, low-level and highly frequent noise exposure is occurring in areas along concentrated flight paths even far from airports, resulting in severe noise complaints, but such areas are far out of noise zones for countermeasures, and not applicable for legal compensation against noise damage. We should consider, however, whether noise annoyance may have changed over time, and whether energy- based noise metrics could have appropriately evaluated the effects of low-level and highly frequent noise with different sound qualities. Thus, we considered a possibility to decrease noise annoyance by devising flight operation control procedures, assuming that ‘awareness of aircraft passing overhead may increase annoyance’ 33,34,35) . It suggested a possibility to reduce noise impact by devising operational procedures and reducing awareness of aircraft flyover, although it is not easy to test such procedures and confirm their effectiveness in practice. 6. CONCLUSIVE REMARKS

This paper described a result of considering changes in community annoyance with aircraft noise over the times. First, it briefly reviewed the progress in noise reduction of civil aircraft over time. The certification noise level seems to have decreased at a rate of 0.2~0.25 dB/year/certification point, which matches the decrease rate 0.25~0.29 dB/year of sound level observations at Narita. Next, it described a result of comparing eight dose-response curves on noise annoyance. The result of comparing four meta-analyses does not contradict with the ISO-1996-1 suggestion that the prevalence of high annoyance with aircraft noise in social surveys increases at a rate of about 0.2 dB per year, but this author supposed that the phase-out of high noise turbojet aircraft may have contributed to the difference in the rate of %Highly-Annoyed with aircraft noise during the turn of the century, at least in Japan. Anyway, considering the high progress in aircraft noise reduction at the source, we cannot help but be surprised at the strong intensification of the response. Then, this paper made a brief review of recent noise issues associated with the introduction of new air traffic management systems using wide-area navigation or new flight routes. People under the concentrated flight routes appeals strong concerns about the frequent aircraft flying low overhead and noise annoyance with the aircraft sound like continuous hissing or wailing. Then, this paper described a result of viewing the impact of the coronavirus pandemic on air traffic and noise situation near the airport over the last two years or longer. Finally, it gave a minor consideration to future trends in community annoyance with aircraft noise and how to deal with the changes in the annoyance response. More than 60 years have passed since the introduction of jet aircraft to civil aviation, and technological innovations have made aircraft much quieter. Nevertheless, people still complain that they experience severe suffering from aircraft noise. The changes in lifestyles, values concerning the sound environment, and aircraft operating conditions including the air traffic management system over time may have influenced the differences in annoyance responses. 7. ACKNOWLEDGEMENTS

The author gratefully acknowledges Naoaki Shinohara for the cooperation of Mr. Naoaki Shinohara, Director of the Research Center, in collecting data necessary to depict graphs in Chapter 2 and 4. The author also thanks Mr. Makoto Morinaga of Kanagawa University for his advice in preparing the Japanese data of dose response curves used in Chapter 2. 8. REFERENCES

1. ISO 1996-1:2016: Acoustics - Description, measurement, and assessment of environmental

noise - Part 1: Basic quantities and assessment procedures. 2. WHO EUROPE, Environmental Noise Guidelines for the European Region, 2018. 3. ICAO ENVIRONMENT WEB Pages, Technologies Standards (Reduction of Noise at Source).

4. Neil Dickson, Aircraft Noise Technology and International Noise Standards, ICAO

Environmental Workshops, 2015. 5. Arnaud Bonnet (ICCAIA Observer at CAEP), The role of technology in reducing aircraft noise,

ICAO Environmental Symposium 2019. 6. Masaom Isobe, Change in Noise Exposure around Airport : Narita International Airport, Journal

of INCE/J, Vol.31, NO.2 2007. 7. ISO 1996 – Acoustics - Description, measurement, and assessment of environmental noise -

Part 1: Basic quantities and assessment procedures, 2016. 8. FICON, Federal Agency Review of Selected Airport Noise Analysis Issues, August 1992. 9. Miedema HM, Oudshoorn CG (2001). Annoyance from transportation noise: relationships with

exposure Metrics DNL and DENL and their CIs. Environ Health Perspect. 109:409–16. 10. FAA Aviation Noise WEB Pages, Neighborhood Environmental Survey. 11. Sean Doyle et al., U.S. Federal Aviation Administration Research on Aviation Noise:

Understanding Challenges, Developing Solution, and Informing Decision Making, Proc. ICBEN 2021. 12. Sean Doyle et al., U.S. Federal Aviation Administration noise research program including the

Neighborhood Environmental Survey motivation and results, Proc. INTERNOISE 2021. 13. Makoto Morinaga, Discussion of aircraft noise standards based on dose-response relationships

in Japan, Proceedings of INCE/J Autumn Meeting, 2020. 14. Ichiro Yamada and Jiro Kaku, Changes in community reactions to the changes in aircraft noise

exposure situations, J. Acoust. Soc. Jpn, 55(7) 1999. 15. J. Kaku, et al., “Standardization of social survey method in Japan”, Proc. INTER-NOISE 2004. 16. Kana Hemmi, Takashi Yano and Tetsumi Sato, Social Survey on Community Response to

Aircraft Noise around Kumamoto Airport, Summaries of technical papers of Annual Meeting Architectural Institute of Japan 2007. 17. Masaaki HIROE et al., A questionnaire survey on health effects of aircraft noise for residents

living in the vicinity of Narita International Airport: The results of physical and mental health effects, Table 4 in Proc. ICBEN 2017. 18. Ichiro Yamada, “Continuing efforts and challenges to reduce the impact of airport noise in

Japan.” Proc. INTER-NOISE 2012. 19. Ichiro Yamada, Considering noise policy for low-noise but frequent fly-over events far from the

airport, Proc. ICBEN 2014. 20. Aviation Wire, ‘Haneda new route, MLIT to hold review study meeting. Utilizing the

conventional route?’ Archives/204889, JUN 19, 2020. 21. MLIT Website, ‘Meeting materials of Technical Measures Study Group on Avoiding the

Fixation of the Haneda New Route. 22. FAA NextGen WEB Pages, Next Generation Air Transportation System (NextGen). 23. CYNTHIA SCHULTZ, NextGen Noise: RNP’s concentrated impact may justify substantive

change in FAA Policies under a proper study, JDA Journal, DEC 28, 2015. 24. SANDY MURDOCK, Replay From 2015: NextGen Noise: RNP’s Concentrated IMPACT May

Justify Substantive Change in FAA Policies Under a proper study, JDA Journal, MAR 26, 2019 25. The unheard-of noise pollution from the FAA’s wasteful NextGen program, The Washington

Post on 14 March 2018. 26. Paul Lewis, Frustration on Progress, Concern About Noise are Key Topics at House NextGen

ATC Roundtable, Eno Center for Transportation, May 20, 2021. 27. Michael Wildes, FAA Responds to Call of Lawmakers to Mitigate Noise Impacts, FLYING,

March 18, 2022. 28. Teddington Action Group, PERFORMANCE BASED NAVIGATION (PBN), FLIGHT

PATHS AND AIRSPACE CAPACITY, 1 6TH MAY 2018. 29. Kansai Airport, Aircraft noise measurement results, downloaded from WEB Pages. 30. Narita International Airport, Environmental report, downloaded from WEB Pages.

31. Janet Daby, MP for Lewisham East, In My View, South London Press, 26 AUG 2021, London

News WEB Pages. 32. Air Traffic Movement Outlook - Europe August 2021, IATA analysis based on IATA / Tourism

Economics Air Passenger Forecast July 2021; EUROCONTROL STATFOR May 2021 ECAC forecast, IATA WEB Pages. 33. Ichiro Yamada, “Continuing efforts and challenges to reduce the impact of airport noise in

Japan.” Proc. INTER-NOISE 2012. 34. Ichiro Yamada et al., “Influence of visual image of the sound source on noise annoyance of air

and high-speed rail transport,” Proc., ASJ, SEP (2018). 35. Ichiro Yamada, Considering the influence of the sound source noticeability on aircraft noise

annoyance, Proc. INTER-NOISE 2019.