Assessing the changing urban sound environment during the COVID-19 lockdown period using short-term acoustic measurements

TLDR

Lockdown measures imposed by COVID‑19 have produced wide‑ranging social and environmental effects, including a city‑scale decline in urban noise levels documented through Environmental Noise Directive noise mapping. The study seeks to determine how these lockdown measures alter the person‑level experience of the urban soundscape locally and how such effects vary across different urban space typologies. In London, 30‑second binaural recordings were taken at 11 public spaces before (N = 620) and during lockdown (N = 481), five acoustic and psychoacoustic metrics were calculated, and clustering analysis grouped the sites into three acoustic‑characteristic types. An average 5.4 dB reduction in LAeq was found, with site‑specific decreases ranging from 10.7 dB to 1.2 dB, confirming a general noise decline and highlighting context‑dependent trends that inform limits of urban noise reduction.

Abstract

Abstract The implementation of lockdown measures due to the COVID-19 outbreak has resulted in wide-ranging social and environmental implications. Among the environmental impacts is a decrease in urban noise levels which has so far been observed at the city scale via noise mapping efforts conducted through the framework of the Environmental Noise Directive. This study aims to understand how lockdown measures have manifested at a local level to better determine how the person-level experience of the urban soundscape has been affected and how these affects differ across urban space typologies. Taking London as a case study, a series of 30-second binaural recordings were taken at 11 locations representing a cross-section of urban public spaces with varying compositions of sound sources during Spring 2019 (pre-lockdown, N = 620) and Spring 2020 (during-lockdown, N = 481). Five acoustic and psychoacoustic metrics ( LA eq , LA 10 , LA 90 , Loudness, Sharpness) were calculated for each recording and their changes from the pre-lockdown scenario to the lockdown scenario are investigated. Clustering analysis was performed which grouped the locations into 3 types of urban settings based on their acoustic characteristics. An average reduction of 5.4 dB ( LA eq ) was observed, however significant differences in the degree of reduction were found across the locations, ranging from a 10.7 dB to a 1.2 dB reduction. This study confirms the general reduction in noise levels due to the nationally imposed lockdown measures, identifies trends which vary depending on the urban context and discusses the implications for the limits of urban noise reduction.