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    How did "state of emergency" declaration in Japan due to the COVID-19 pandemic affect the acoustic environment in a rather quiet residential area?

     Kimihiro Sakagami (corresponding) (2020)
    The COVID-19 pandemic caused lockdown in many countries. Acousticians made surveys to monitor how cities became quieter under the lockdown, mainly in the central areas of cities. However, there have been few studies on changes in the acoustic environment due to the pandemic in rather quieter residential areas. It may be expected to be different from the effect in originally noisy areas. Also, the effect could be different in Japan, because the "state of emergency" declaration there was different to lockdown. Considering these circumstances, this paper reports the results of noise monitoring and makes some observations on the acoustic environment in residential areas remote from city centres, to provide an example of how the acoustic environment was affected by the "state of emergency" declaration due to the COVID-19 pandemic in Japan. The results showed that the reduction of noise levels was somewhat smaller than that reported in large cities. Also, comparing the results after the cancellation of the "state of emergency", the noise level increased again. However, observations of noise sources imply that a possible change in human behaviour may have also affected the acoustic environment.

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      This work has been published open access under Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Conditions, terms of use and publishing policy can be found at


      Review text

      The study investigates the impact of the “state of emergency” declaration due to the COVID-19 pandemic on the acoustic environment of a residential area in Japan. The acoustic community has been mobilized to measure and characterize the impact of the COVID outbreak and consequent confinement situation on noise exposure and on people´s perception (i.e. the soundscape) in several cities around the world [1,2]. Interestingly, this manuscript contributes to this global measurement campaign with some elements of peculiarity. Indeed, i) it focuses on a quiet residential urban area and not on a busy city center and ii) it aims at measuring the effect of Japan´s “state of emergency declaration” that was someway different compared to the “lockdown” policies implemented in many different countries, as explained by the Author. The main suggestions and comments on the manuscript are reported in the following:

      • Given the limitations in measurement capabilities due to the “state of emergency” situation, the paper provides a comparison of exposure levels before, during and after the emergency period relying on short measurements of equivalent continuous A-weighted sound pressure levels LAeq (T=30 s) gathered through the NoiseCapture app for Android [3]. The Author reports that a “detailed check of accuracy was not performed” but that the app had been calibrated using a Class 1 SLM before emergency period. If absolute levels might not be accurate, relative levels (before vs. during vs. after the state of emergency period) are useful for the sake of comparison. The data collection methods and the very short duration of recordings (30s) limit the data quality and representativeness and do not allow to align with the recent proposal of harmonization for data reporting by Asensio et al. [2]. This latter aspect would have been important to allow for a comparison and integration of data provided by this study with other gathered from similar initiatives, in future meta-analysis;
      • Comparison of noise levels (LAeq (T=30 s)) at the six measurement points (Table 1) or at fixed recording positions (Fig. 2-4) do not show consistent trends. When referring to the exposure values averaged across the six measurement points, a slight increase in noise levels can be observed during and immediately after the emergency phase compared to the period before the pandemic outbreak. This is someway in contrast with what can be expected and, according to the Author, might be related to the increased traffic volume observed and to the construction works that were present in that area. This effect should be better described in the Concluding remarks section, where the Author describes a “1–2 dBA” effect, without clearly specifying the direction of the change. Moreover, the measurement methodology (recording device and length of recordings) limit the general validity of results;
      • Besides noise levels, interestingly the Author reports the composition of perceived sound sources. Even if no statistical inference was sought. descriptive statistics suggest no difference during and after the “state of emergency” situation.

      Taken together, the study contributes to current research efforts on the characterization of the impact of the COVID-19 scenario on urban soundscape and on the use of smartphones for recording purposes. Clear trends in the noise dose and sound type composition could not be observed by comparing the different time periods (i.e. before, during and after the state of emergency declaration). This might be due to the different impact of “the state of emergency” compared to a “lockdown” situation and/or to differences of the impacts in a residential area compared to city centers. Anyway, due to data collection limitations, no sound conclusion or generalization can be done at this stage, as also stressed by the Author.



      1. Aletta, F.; Osborn, D. The COVID-19 global challenge and its implications for the environment – what we are learning. UCL Open Environ. 2020, 8–10.

      2. Asensio, C.; Aumond, P.; Can, A.; Gasc, L.; Lercher, P.; Wunderli, J.; Lavandier, C.; Arcas, G. De; Ribeiro, C.; Muñoz, P.; et al. A Taxonomy Proposal for the Assessment of the Changes in Soundscape Resulting from the COVID-19 Lockdown. 2020, 1–9.

      3. Picaut, J.; Fortin, N.; Bocher, E.; Petit, G.; Aumond, P.; Guillaume, G. An open-science crowdsourcing approach for producing community noise maps using smartphones. Build. Environ. 2019, 148, 20–33.


      Response to  the Review by Simone Torresin

      Dear Reviewer 

      The author appreciates the detailed and constructive review very much. In the current revision, the author tried to address all the points raised. Below, the summary of the revision is given.

      Regarding the first point, as mentioned in the text, due to the restrictions during the survey, a mobile device and Noise Capture app  were used. After the survey, the accuracy test was performed and rather good accuracy was confirmed. Therefore, the measured values are of reasonable accuracy, and at least enough for the relative values and qualitative discussions. (Please see the Appendix in the current version.)

      As for the second point, though it is rather difficult to give explicit comments, more detailed explanation was  attempted in related parts, particularly in the concluding remarks. Regarding the generality, as this is a simple interim  case report, generalisation was not intended, and the present results are limited to this area. 

      Regarding the third point, the most difficult in this survey was that the declaration of the state of emergency was made with short notice, and the author did not have the record of the perceived sound source. This prevents an explicit discussion on this point: the difference between before the emergency and during it. As it may show further change later, the author expects that it can be possible to obtain some more insight in this point.

      As pointed out, the method, especially the short-term averaging is different from the method by Asensio will prevent to compare the present work with the others. However, it was necessary to compare with the author’s previous data taken in 2019. Also, the motivation of the study was to know whether there was a difference between before the state of emergency and during it. This circumstances are now more clearly mentioned in the current version.

      The author hopes to perform a follow-up survey, and in that case he will use the standard method as suggested.

      As the reviewer summarised, the author understands that the present work only provides an example in which the “state of emergency “ , which is somewhat different than lockdown though, did not show significant difference in acoustic environment. The reasons for this can be considered as either the surveyed area was originally quiet, or the difference in the scheme of emergency situations. 

      Once again, the author appreciates the reviewer for his feedback.

      Kind regards

      Kimihiro Sakagami (Author)

      (End of the reply)

      2020-07-18 02:51 UTC
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