THE EFFECTS OF NOISE ON HEARING

The Effects Of Noise On Hearing

The Effects Of Noise On Hearing

Introduction

The disturbing presence of noise in modern society is the well-known form of environmental pollution. In daily usage, noise refers to an unwanted annoying auditory input. Almost exclusively, noise is experienced as disturbing, and its effects were shown to be negative in the variety of investigations. In presence of the weak, subthreshold signal, very soft noise may, however, have the beneficial effect (Moss et al., 2004). This phenomenon, termed stochastic resonance, consists of enhancement of information content of the weak signal in nonlinear human-made or natural sensory systems. Such enhancement is more likely to occur in presence of background noise and in correspondence of threshold crossings near peaks of signal (Moss et al., 2004). In auditory system, stochastic resonance may improve detection levels of individuals with hearing aids, because of energy combination of noise and stimulus (Zeng et al., 2000; cf. also [Tanaka et al., 2008] and [Ward et al., 2001]). It is important to note that optimal noise level necessary to induce stochastic resonance in auditory system is very soft as it corresponds to absolute threshold for noise alone. Otherwise moderate noise typically interferes with detection and identification of the suprathreshold signal. This process is called masking (Moore, 2004). Factors such as loudness or type of noise, or personal characteristics of individual contribute to experienced annoyance of noise. For example, continuous noise is usually less disturbing than noise which includes acoustic variation and loud background noise has generally greater harmful effects both physiologically and subjectively than soft noise (e.g., [Kjellberg, 1990], [Sperry et al., 1997] and [Stuart and Philips, 1997]). Some individuals are more sensitive to noise than others, which is reflected in their subjective ratings of noise annoyance as well as in neural processing during noise conditions (Pripfl et al., 2006).

Psychological Effects of Noise & Sounds On The Human Brain

The detrimental physiological effects of high-amplitude noise, causing both functional and structural changes, have been investigated intensively. However, according to recent evidence, even soft-intensity suprathreshold background noise may adversely affect brain function. For instance, background noise in some situations and for certain kinds of individuals may considerably interfere with speech perception. Furthermore, exposure to long-term noise may have persisting effects on brain function and behavior even when peripheral hearing is intact. We will here review literature concerning short- and long-term background noise effects on brain processes underlying auditory, and particularly, speech perception.

Noise in its various forms has become part of modern life. A large number of citizens in modern environments are daily exposed to background noise. Noise is not only subjectively annoying but it can also have an adverse effect on hearing and health in general. However, in light of recent evidence, even such levels of noise that do not cause damage to peripheral hearing can have the persistent effect on speech brain function, perception, and attention control, affecting individual's behavior.

Some groups of individuals are particularly vulnerable to background ...