Wind Turbine Infra and Low-Frequency Sound: Warnings signs that were not heard

Abstract

Industrial wind turbines are frequently thought of as benign. However, the literature is reporting adverse health effects associated with the implementation of industrial-scale wind developments. This article explores the historical evidence about what was known regarding infra and low-frequency sound from wind turbines and other noise sources during the period from the 1970s through the end of the 1990s. This exploration has been accomplished through references, personal interviews and communications, and other available documentation. The application of past knowledge could improve the current siting of industrial wind turbines and avoid potential risks to health.

Introduction

Over the past 20 or so years, the wind industry has presented evidence implying that industrial-scale wind turbines are safe near people’s homes. Yet reports of high levels of annoyance, sleep disturbance, and body/vestibular responses have been received from people living within 2 or more kilometers of wind turbines located in countries around the world. Is it possible that these adverse effects could have been foreseen by those who manufacture and/or install and operate industrial scale wind turbine utilities in quiet rural/ residential communities? 

This article reviews some of the history and early research regarding infra and low-frequency sound. This is not an exhaustive review. It explores what was known about infra and low-frequency sound from wind turbines and other noise sources during the period from the 1970s through the end of the 1990s. The work of three groups of acoustical researchers provides valuable historical research relating to human response to low levels of infra and low-frequency noise. Their work will be referenced throughout this article to provide historical context. 

• Group 1 was involved with other types of large machines that produce dynamically modulated infra and low-frequency sound. 

• Group 2 was involved with identifying and correcting problems caused by dynamically modulated heating and cooling system fans used in high-rise office complexes.

• Group 3 conducted research into the specific nature of wind turbine sound emissions, propagation, and how sound could affect people living near wind turbines. To better understand earlier work, the author established personal contact with several of the acoustical experts who were the primary investigators of infra and low-frequency sound problems incurred in the past. Past knowledge through personal conversations, review of the reports that were relevant to the solving of these earlier problems, e-mail exchanges in order to understand better what they had experienced or learned about infra and low-frequency sound is explored throughout the article.

This article acknowledges the adverse health effects (AHEs) of audible sound, particularly as it relates to nighttime sleep disturbance. However, most of the article will focus on infra and low-frequency noise. It is assumed that the reader has a basic understanding of how infra and low-frequency sounds are characterized and the terminology that is associated with this characterization. For further information, please refer to the article by Dr. John Harrison (2011, 2010b) for a review of terms and concepts.