Pattern A personality and noise-induced vasoconstriction.

A perplexing question about noise-induced hearing loss is why some persons seem to be more affected by high intensity noise than others. Hawkins (1971) has shown noise-induced vasoconstriction to be implicated in noise-induced hearing loss in animals as evidenced by vascular changes within the inner ear and he asks the question: Are these changes caused by the noise itself or mediated by the autonomic nervous system (ANS)? Our research employed a plethysmograph to measure ANS mediated vasoconstriction during noise exposure. The subjects were stress prone males and females (Pattern A) whose behavior in noise was compared to non-stress prone males and females (Pattern B). The results indicated Pattern A males showed marked vasoconstriction in the presence of noise whereas Pattern B males did not. Pattern A females performed very much like Pattern A males with no statistical difference between these two groups. However, Pattern B females demonstrated a significant increase in vasoconstriction in the presence of noise and in this respect Pattern B females are different from Pattern B males. This difference possibly resulted from the use of a test to assess personality type which was intended for use with male subjects. The authors conclude there is strong evidence to suggest that being prone to stress in the presence of noise is a contributing factor to noise-induced hearing loss.