Feasibility assessment of a new method for measurement of hearing protector attenuation: bone conduction loudness balance.
Appl Occup Environ Hyg 1997 Jan; 12(1):69-75
A feasibility assessment of a new method for evaluating hearing protector attenuation was performed. The new procedure known as the bone conduction loudness balance (BCLB) technique involved measuring the attenuation of a hearing protector as the difference caused by the protector in the loudness of air conducted sound required to balance the loudness of a bone conducted reference sound. The BCLB procedure was performed with four volunteers wearing or not wearing expandable foam earplugs under two conditions: being exposed to pure tones ranging from 1 to 4,000 hertz (Hz), and to a 0.33 octave noise band centered at 2,000Hz covering the same frequency band. The air conduction sounds which were pure tones equal to the BCLB pure tones were delivered by standard audiometric head phones. The bone conduction sounds were produced by a vibrator held to the subjects' foreheads. The degree of attenuation of the earplugs determined by the two BCLB procedures were compared with that measured by the standard real ear attenuation at threshold (REAT) procedure. For both BCLB procedures, more than 85% of the differences with the REAT data were smaller than 4 decibels. When the repeatability of the data was evaluated, the average percentage of error across all subjects was approximately equal for all three methods, the percentage error varying from 7.5 to 12.5%. All four subjects reported that the pure tone BCLB test was easier to perform than the noise band BCLB test. The authors conclude that the new BCLB procedure appears to be comparable to the standard REAT method.
NIOSH-Publication; NIOSH-Grant; Noise-induced-hearing-loss; Hearing-protection; Hearing-tests; Psychophysiology; Noise-protection
Work Environment University of Lowell One University Ave Lowell, MA 01854
Applied Occupational and Environmental Hygiene
University of Massachusetts Lowell, Lowell, Massachusetts