Auditory and non-auditory effects of noise on health

Divided attention: Evidence for coactivation with redundant signals

Noise is pervasive in everyday life and can cause both auditory and non-auditory health eff ects. Noise-induced hearing loss remains highly prevalent in occupational settings, and is increasingly caused by social noise exposure (eg, through personal music players). Our understanding of molecular mechanisms involved in noise-induced haircell and nerve damage has substantially increased, and preventive and therapeutic drugs will probably become available within 10 years. Evidence of the non-auditory eff ects of environmental noise exposure on public health is growing. Observational and experimental studies have shown that noise exposure leads to annoyance, disturbs sleep and causes daytime sleepiness, aff ects patient outcomes and staff performance in hospitals, increases the occurrence of hypertension and cardiovascular disease, and impairs cognitive performance in schoolchildren. In this Review, we stress the importance of adequate noise prevention and mitigation strategies for public health.

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Auditory and non-auditory eff ects of noise on health

Exposure to noise constitutes a health risk. There is sufficient scientific evidence that noise exposure can induce hearing impairment, hypertension and ischemic heart disease, annoyance, sleep disturbance, and decreased school performance. For other effects such as changes in the immune system and birth defects, the evidence is limited. Most public health impacts of noise were already identified in the 1960s and noise abatement is less of a scientific but primarily a policy problem. A subject for further research is the elucidation of the mechanisms underlying noise-induced cardiovascular disorders and the relationship of noise with annoyance and nonacoustical factors modifying health outcomes. A high priority study subject is the effects of noise on children, including cognitive effects and their reversibility. Noise exposure is on the increase, especially in the general living environment, both in industrialized nations and in developing world regions. This implies that in the twenty-first century noise exposure will still be a major public health problem.

Noise exposure and public health.

We present a model of the distribution of noise annoyance with the mean varying as a function of the noise exposure. Day-night level (DNL) and day-evening-night level (DENL) were used as noise descriptors. Because the entire annoyace distribution has been modeled, any annoyance measure that summarizes this distribution can be calculated from the model. We fitted the model to data from noise annoyance studies for aircraft, road traffic, and railways separately. Polynomial approximations of relationships implied by the model for the combinations of the following exposure and annoyance measures are presented: DNL or DENL, and percentage "highly annoyed" (cutoff at 72 on a scale of 0-100), percentage "annoyed" (cutoff at 50 on a scale of 0-100), or percentage (at least) "a little annoyed" (cutoff at 28 on a scale of 0-100). These approximations are very good, and they are easier to use for practical calculations than the model itself, because the model involves a normal distribution. Our results are based on the same data set that was used earlier to establish relationships between DNL and percentage highly annoyed. In this paper we provide better estimates of the confidence intervals due to the improved model of the relationship between annoyance and noise exposure. Moreover, relationships using descriptors other than DNL and percentage highly annoyed, which are presented here, have not been established earlier on the basis of a large dataset.

Annoyance from transportation noise: Relationships with exposure metrics DNL and DENL and their confidence intervals

More than a decade has passed since a relationship between community noise exposure and the prevalence of annoyance was synthesized by Schultz [T. J. Schultz, J. Acoust. Soc. Am. 64, 377–405 (1978)] from the findings of a dozen social surveys. This quantitative dosage–effect relationship has been adopted as a standard means for predicting noise‐induced annoyance in environmental assessment documents. The present effort updates the 1978 relationship with findings of social surveys conducted since its publication. Although the number of data points from which a new relationship was inferred more than tripled, the 1978 relationship still provides a reasonable fit to the data.

Updating a dosage-effect relationship for the prevalence of annoyance due to general transportation noise

The findings of 21 studies of the effects of noise on sleep were reanalyzed in an effort to develop a quantitative dosage‐response relationship. Large and systematic differences in sleep disturbance were observed between the findings of studies conducted in laboratory and in field settings. The influence of noise on sleep was also found to depend on additional factors such as the nature of noise and response metrics, noise source, background noise level, length of study, and sex of test participants. No reliable quantitative model for sleep disturbance could be developed from the studies reviewed.

Predicting noise‐induced sleep disturbance

Numerous relationships between noise exposure and transportation noise-induced annoyance have been inferred by curve-fitting methods. The present paper develops a different approach. It derives a systematic relationship by applying an a priori, first-principles model to the findings of forty three studies of the annoyance of aviation noise. The rate of change of annoyance with day-night average sound level (DNL) due to aircraft noise exposure was found to closely resemble the rate of change of loudness with sound level. The agreement of model predictions with the findings of recent curve-fitting exercises (cf. Miedma and Vos, 1998) is noteworthy, considering that other analyses have relied on different analytic methods and disparate data sets. Even though annoyance prevalence rates within individual communities consistently grow in proportion to duration-adjusted loudness, variability in annoyance prevalence rates across communities remains great. The present analyses demonstrate that 1) community-specific differences in annoyance prevalence rates can be plausibly attributed to the joint effect of acoustic and non-DNL related factors and (2) a simple model can account for the aggregate influences of non-DNL related factors on annoyance prevalence rates in different communities in terms of a single parameter expressed in DNL units—a “community tolerance level.”

A first-principles model for estimating the prevalence of annoyance with aircraft noise exposure.

The contemporary technical rationale for assessing effects (“impacts”) of transportation noise on communities rests in large part on a purely descriptive dosage-effect relationship of the sort first synthesized by Schultz [J. Acoust. Soc. Am. 64, 377–405 (1978)]. Although U.S. federal adoption of an annoyance-based rationale for regulatory policy has made this approach a familiar one, it is only one of several historical perspectives, and not necessarily the most useful for all purposes. Last reviewed by the U.S. Federal Interagency Committee on Noise (FICON) 10 years ago, the accuracy and precision of estimates of the prevalence of a consequential degree of noise-induced annoyance yielded by functions of noise exposure leave much to be desired. This tutorial article traces the development of the dosage-effect relationship on which FICON currently relies, in a wider historical context of efforts to understand and predict community response to transportation noise. It also identifies areas in which advances in genuine understanding might lead to improved means for predicting community response to transportation noise.

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The Schultz curve 25 years later: a research perspective.

Field measurements were conducted of potential sleep disturbance associated with changes in nighttime aircraft noise exposure near three airports. One study was conducted near Stapleton International Airport (DEN) and Denver International Airport (DIA) in anticipation of the closure of the former and opening of the latter. Sleep behavior was monitored in 57 homes located near runway ends at the two airports. A second study was conducted in the vicinity of DeKalb-Peachtree Airport (PDK), a large general aviation airport that expected increased nighttime flight operations due to the Olympic Games in July and August of 1996. Similar methods of measuring nighttime noise levels and sleep disturbance in the two studies were maintained over the course of 2717 and 686 subject-nights of observations, respectively. No major differences in noise-induced sleep disturbance were observed as a function of changes in nighttime aircraft noise exposure.

Sanford Fidell

Papers

Updating a dosage-effect relationship for the prevalence of annoyance due to general transportation noise

Predicting noise‐induced sleep disturbance

A first-principles model for estimating the prevalence of annoyance with aircraft noise exposure.

The Schultz curve 25 years later: a research perspective.

Effects on sleep disturbance of changes in aircraft noise near three airports.