ADVERSE EFFECTS OF OCCUPATION AND ENVIRONMENT ON HUMAN VOICE

Abstract

In modem societies about one third of the labor force are working in professions in which voice is the primary tool. Voice problems are common in general, but they are even more common in professions in whicp. there is heavy vocal loading, i.e. professions that do not only require prolonged voice use, but also involve extra loading factors such as background noise, long speaking distance, poor room acoustics, lack of adequate equipment like voice amplifiers etc. Other environmental conditions rather than those of work may also have many harmful effects on voice such as chemical and biological pollution (Vilkman, 2000).

There are many environmental pollutants that may affect voice adversely at work or any where else. The most important one is noise which is a type of non chemical environmental pollution that may be responsible for voice abnormalities. Noise can disturb man's work, rest, sleep and communication. It can cause a complex physiological, psychological and even pathological reactions (Sataloff, 1992). Speakers change the level of their voice when they listen to noise. When noise level is increased, voice becomes louder. This can be explained through the auditory feed back loop. The tendency to increase one's vocal intensity in response to noise is called the