Active noise reduction audiometry: a prospective analysis of a new approach to noise management in audiometric testing.
OBJECTIVE
To develop a new method of screening audiometry that reduces the adverse effects of low frequency background noise by using active noise reduction (ANR) headphone technology.


METHODS
Prospective testing within an anechoic chamber evaluated the physical properties of ANR headphones. A prospective clinical crossover study compared standard audiometry with ANR headphone audiometry.


METHODS
Bose Aviation X circum-aural ANR headphones were tested for both active and passive attenuation properties in a hemi-anechoic chamber using a head and torso simulator. Thirty-seven otology clinic patients then underwent standard audiometry and ANR audiometry, which was performed in a 30- and/or 40-dB sound field.


RESULTS
Objective ANR headphone attenuation levels of up to 12 dB were achieved at frequencies below 2,000 Hz. In standard audiometric testing, 40 dB of narrow-band background noise decreased patient pure tone thresholds by 24 dB at 250 Hz. The use of ANR technology provided 12 dB of additional attenuation. This resulted in a significant improvement in test results despite the 40 dB of background noise (P = <0.001). In a 30-dB sound field, standard audiometric thresholds were shifted down by an average of 12 dB. The use of ANR technology completely attenuated this effect and resulted in a significant improvement in results (P = <0.01). These results were identical to those obtained in a quiet sound booth.


CONCLUSIONS
Despite a 30-dB sound field, ANR audiometry can produce an audiogram identical to that obtained in a double-walled sound booth. ANR headphone audiometry improves the sensitivity of audiometric screening for mild low-frequency hearing loss. This technology may have important applications for screening in schools, industry, and community practices.
Department of Otolaryngology, Elborne College, University of Western Ontario, 339 Windermere Road, London, Ontario, Canada.
Matthew A
MA
Bromwich
Vijay
V
Parsa
Nicole
N
Lanthier
John
J
Yoo
Lorne S
LS
Parnes
D001299:Audiometry / Q000295:instrumentation* / Q000379:methods; D001301:Audiometry, Pure-Tone / Q000295:instrumentation / Q000379:methods; D001309:Auditory Threshold / Q000502:physiology; D018592:Cross-Over Studies; D004430:Ear Protective Devices; D004867:Equipment Design; D034381:Hearing Loss / Q000145:classification / Q000175:diagnosis; D006801:Humans; D009622:Noise / Q000517:prevention & control*; D011446:Prospective Studies; D013016:Sound