Long-term quantification and characterisation of wind farm noise amplitude modulation

TL;DR

This study provides a comprehensive one-year analysis of wind farm noise amplitude modulation, revealing its diurnal and meteorological patterns, indoor versus outdoor differences, and implications for noise impact assessments.

Contribution

It offers the first long-term characterization of wind farm noise amplitude modulation, including indoor and outdoor variations and meteorological influences.

Findings

Nighttime AM prevalence is 2-5 times higher outdoors.

Indoor AM occurs less often but with higher depth at night.

AM is more frequent during downwind and crosswind conditions.

Abstract

The large-scale expansion of wind farms has prompted community debate regarding adverse impacts of wind farm noise (WFN). One of the most annoying and potentially sleep disturbing components of WFN is amplitude modulation (AM). Here we quantified and characterised AM over one year using acoustical and meteorological data measured at three locations near three wind farms. We found that the diurnal variation of outdoor AM prevalence was substantial, the nighttime prevalence was approximately 2 to 5 times higher than the daytime prevalence. On average, indoor AM occurred during the nighttime from 1.1 to 1.7 times less often than outdoor AM, but the indoor AM depth was higher than that measured outdoors. We observed an association between AM prevalence and sunset and sunrise. AM occurred more often at downwind and crosswind conditions. These findings provide important insights into long term WFN characteristics that will help to inform future WFN assessment guidelines.