Accession Number : ADA301581

Title :   Noise Environs and Helmet Performance for the P-1127 V/STOL Aircraft.

Descriptive Note : Final rept. Oct 67-Mar 68,

Corporate Author : AIR FORCE AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Sommer, Henry C. ; Rose, Justus F. ; Knoblach, William C.

PDF Url : ADA301581

Report Date : DEC 1968

Pagination or Media Count : 29

Abstract : The purpose of this evaluation was (1) to measure the acoustic noise environment in the cockpit of the United Kingdom Hawker Siddeley P-1127 V/STOL aircraft that would serve as an acoustic guideline for cockpit noise levels of other V/STOL aircraft being contemplated or under construction, and (2) to determine the acoustic attenuation of various Air Force flight helmets in the inventory or being contemplated for Air Force inventory items. Cockpit sound pressure levels in the United Kingdom Hawker Siddeley P-1127 V/STOL aircraft at engine rpm settings of idle, 45%, 60%, 80% and maximum were measured. The cockpit noise environment at maximum engine rpm was reproduced in the laboratory and used to obtain objective attenuation data for three Air Force flight helmet/liner configurations (HGU-2A/P helmet with 17P liner, H-154 ear cup liner and Gentex ear cup liner). Measurement of Real-Ear Attenuation at Threshold (REAT) were also accomplished on the helmet/liner configurations. On the basis of the cockpit noise environment and the attenuation characteristics of the helmet/liner configurations tested, no hearing damage would be expected to result when exposure durations do not exceed 1 hour continuous exposure. The Gentex ear cup liner provides approximately 4 to 9 dB more attenuation than the 17P liner throughout the frequency range tested and from 13 to 26 dB more attenuation than the H-154 ear cup liner at test frequencies from 3 to 8K Hz.

Descriptors :   *FLIGHT HELMETS, *NOISE(SOUND), TEST AND EVALUATION, FREQUENCY, ENVIRONMENTS, EXPOSURE(GENERAL), COCKPITS, TIME, AIR FORCE PERSONNEL, LININGS, CONFIGURATIONS, LEVEL(QUANTITY), ATTENUATION, INVENTORY, NOISE, ACOUSTIC ATTENUATION, SOUND PRESSURE, GREAT BRITAIN, VERTICAL TAKEOFF AIRCRAFT, SHORT TAKEOFF AIRCRAFT, DEAFNESS.

Subject Categories : Acoustic Detection and Detectors
      Infrared Detection and Detectors

Distribution Statement : APPROVED FOR PUBLIC RELEASE