Studies on the clinical signs of imparment of conductive apparatus due to noise

Abstract

The author have studied on the clinical signs of impairment of conductive apparatus due to noise in laborers in the extremly noisy sections of a big automobile works in Japan. Morita's otoscopic goniometer modulated by author was used to measure the degree of retraction of ear drum. Reduction of conductive function was principally examined by Onchi's occluded bone conduction method. Following conclusions were obtained:1) By the exposure to noise, the conductive apparatus is more or less impaired besides perceptive apparatus in most of the cases, and its conductive function is reduced almost in half of them.2) The otoscopic findings of impaired conductive apparatus due to noise are retraction of ear drum, and injection of vessels in upper-posterior ouadrant or along the handle of hammer of ear drum. It seems that the retraction of ear drum plays a little role in the decrease of conductive function but injection of vessels plays some role in it.3) According to the various tests, it seems that there are some disorders of occicular chain due to noise and decrease of conductive function based mainly upon these disorders.4) In audiogramm of air conduction, it is found that the hearing loss of the ear which is accompanied by decrease of conductive function is little larger in lower and middle tonerange and is little smaller in high tonerange especially at 4, 000cps than that of the ear which conductive function is not reduced. But it is impossible to find out the decrease of conductive function by only the audiogramm of air conduction on each ear.