Factors affecting the benefits of high-frequency amplification.
OBJECTIVE
This study was designed to determine the extent to which high-frequency amplification helped or hindered speech recognition as a function of hearing loss, gain-frequency response, and background noise.


METHODS
Speech recognition was measured monaurally under headphones for nonsense syllables low-pass filtered in one-third-octave steps between 2.2 and 5.6 kHz. Adults with normal hearing and with high-frequency thresholds ranging from 40 to 80 dB HL listened to speech in quiet processed with an identical "nonindividualized" gain-frequency response. Hearing-impaired participants also listened to speech in quiet and noise processed with gain-frequency responses individually prescribed according to the National Acoustic Laboratories-Revised (NAL-R) formula.


RESULTS
Mean speech recognition generally increased significantly with additional high-frequency speech bands. The one exception was that hearing-impaired participants' recognition of speech processed by the nonindividualized response did not improve significantly with the addition of the highest frequency band. Significantly larger increases in scores with increasing bandwidth were observed for speech in noise than quiet.


CONCLUSIONS
Given that decreases in scores with additional high-frequency speech bands for individual participants were relatively small and few and did not increase with quiet thresholds, no evidence of a degree of hearing loss was found above which it was counterproductive to provide amplification.
Horwitz
Amy R
AR
Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, USA. horwitar@musc.edu
Ahlstrom
Jayne B
JB
Dubno
Judy R
JR
D000293:Adolescent; D000328:Adult; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D005260:Female; D006310:Hearing Aids; D006311:Hearing Disorders / Q000628:therapy*; D006801:Humans; D008297:Male; D009622:Noise / Q000009:adverse effects; D010700:Phonetics; D013063:Speech Discrimination Tests; D013067:Speech Perception