Accession Number : AD0639180

Title :   AN EVALUATION OF THE DUNBAR-KNIGHT HEARING GUARD.

Descriptive Note : Memo rept.

Corporate Author : NAVAL MEDICAL RESEARCH LAB NEW LONDON CONN

Personal Author(s) : Harris,J. Donald

Report Date : 20 APR 1960

Pagination or Media Count : 7

Abstract : A Dunbar-Knight hearing guard was assessed with the threshold shift method using ten normal-hearing ears, and the results compared with those of the standard Navy V-51 ear plug. The attenuation provided in the frequency region 1,500 - 8,000 cycles is of the order of 20-25 db. Attenuation at 1,000 cycles and below is of the order of 10db or less, and will allow speech communications to pass unhindered. It is recommended that this hearing guard, with its lead mass which will absorb a pressure wave, be assessed at a facility which has standardized techniques for assessing the effect on hearing of impulsive noises. (Author)

Descriptors :   (*EARPHONES, EFFECTIVENESS), HEARING, THRESHOLDS(PHYSIOLOGY), AUDIOMETRY, VOICE COMMUNICATIONS, ATTENUATION, NOISE, FREQUENCY

Subject Categories : Voice Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE