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.