A new hearing protector attenuation measurement method.
Department of Work Environment, School of Engineering, University of Massachusetts, Lowell, Massachusetts 1995 Dec; :1-86
Bone conduction loudness balance (BCLB), a new method for determining the attenuation of hearing protective devices (HPDs), was evaluated. When using BCLB for earplug testing with headphones, pure tones of equal frequency can be used for both the air conduction (AC) and bone conduction (BC) sounds with reasonable accuracy. Using BCLB with an external loudspeaker as the AC sound source makes it impossible to use pure tones of equal frequencies since the occlusion effect will cause an overestimation of attenuation at frequencies under 2000 hertz. A practical way to minimize the occlusion effect is to use a constant frequency noise band as the BC sound against which AC noise bands of varying frequency are balanced. Comparisons of mean A- weighted attenuation for broad band noise of various frequency distributions showed agreement generally within 1 decibel between BCLB and real ear attenuation at threshold (REAT), for earplugs, earmuffs, and earmuffs with earplugs. No significant interference was noted by background noise up to a level typical of industrial audiometric testing environments, 35 decibels-A. No significant differences were noted in BCLB and REAT with regard to administration time and repeatability. The BCLB was found to be accurate, reliable, and practical for determining attenuation for all common types of HPDs.
NIOSH-Grant; Control-technology; Ear-protectors; Personal-protective-equipment; Industrial-noise; Hearing-protection; Acoustical-measurements
Work Environment University of Lowell One University Ave Lowell, MA 01854
Final Grant Report
NTIS Accession No.
Department of Work Environment, School of Engineering, University of Massachusetts, Lowell, Massachusetts
University of Massachusetts Lowell, Lowell, Massachusetts