Hyman Menduke

Intermittent Exposure to Noise: Effects on Hearing

Most studies of the effects of noise upon hearing have dealt with continuous noise exposure. Previous reports on intermittent exposure to noise concluded that it causes less damage to hearing than does continuous exposure to noise of the same intensity. In this investigation, 12,000 workers were screened to find 295 subjects who met the strict criteria of the study. Most of the subjects were exposed to jackhammer noise at peak levels of 118 dBA. Intermittent exposure to intense noise results in very severe loss in high frequencies but relatively little or no hearing loss in the lower frequencies even after many years of exposure. This differs substantially from the effects of continuous exposure to noise of the same intensity. It remains to be determined whether this pattern of hearing results from intermittent exposure to all sorts of noise or only from the kinds of sources investigated in this study.

Humidity Studies and Respiratory Infections in a Public School

* Associate Professor of Otolaryngology, Jefferson Medical College. † Associate Professor of Statistics, Jefferson Medical College. t Courtesy of the wanton Laboratories. This project was supported by The Foundation for Medical Research in Hearing. § Courtesy of the Brown Instrument Co. MOST school absences in the primary grades, at least in the colder parts of our country, seem due either to acute contagious dis-

Scheduling Hearing Testing in Industry

A field investigation was conducted to determine what measures industry can take to avoid the need of a prolonged rest period before performing audiometry in order to avoid measuring TTS. If a plant has numerous employees exposed to loud noise audiometric testing can be very costly if it has to be done after employees have been off then: jobs for 14 hours or more. The purpose of this field study was to develop preliminary guidelines that will enable industry to establish a time schedule for audiometric testing.