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Details

New Hearing Protector Attenuation Measurement Method.

PB97113708

Publication Date	1995
Personal Author	Ellenbecker, M. J.; Rimmer, T. W.
Page Count	90
Abstract	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.
Keywords	Ear protectors Protective equipment Industrial noise Hearing protection Acoustical measurements Bone conduction loudness balance
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	57U - Public Health & Industrial Medicine 94D - Job Environment 68G - Environmental Health & Safety 95D - Human Factors Engineering
Corporate Authors	Massachusetts Univ. at Lowell. Dept. of Work Environment.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199703

New Hearing Protector Attenuation Measurement Method.

New Hearing Protector Attenuation Measurement Method.
PB97113708

Publication Date	1995
Personal Author	Ellenbecker, M. J.; Rimmer, T. W.
Page Count	90
Abstract	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.
Keywords	Ear protectors Protective equipment Industrial noise Hearing protection Acoustical measurements Bone conduction loudness balance
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	57U - Public Health & Industrial Medicine 94D - Job Environment 68G - Environmental Health & Safety 95D - Human Factors Engineering
Corporate Authors	Massachusetts Univ. at Lowell. Dept. of Work Environment.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199703