Brainstem auditory-evoked response (BER) measurements were obtained on adult volunteer subjects who were hearing aid users. The BER's were elicited with click stimulation in several conditions: (1) unaided via earphones, (2) unaided via speaker, and (3) aided via speaker. In the aided condition, subjects adjusted their own hearing aids to their usual comfortable listening level. Aided and unaided audiometric thresholds were also obtained on each subject using pure tones, narrow-band noise, and speech under phones, and using noise and speech in a sound field. Hearing aids were analyzed for frequency response and distortion with a series of inputs and also at user level. Comparisons were made between aided and unaided audiological and BER data. Results indicate that aided BER measurement compared favorably with aided audiological data on cooperative adults and may therefore become useful when applied to hearing aid evaluation procedures for infants and children.

No abstract

Traditionally, the evaluation of auditory functioning in the hearing-aided patient has been limited to subjective response measures. This report demonstrates that brainstem evoked responses can provide an objective and reliable measure of auditory performance in such individuals. Moderate-output body-level aids were worn by three normal-hearing adults, on whom unaided responses had previously been obtained. Highly reliable responses to clicks, tone, and noise bursts were obtained from all subjects. Increases in the gain of the aid, and thus signal loudness, produced shorter latency and larger amplitude responses, as expected on the basis of unaided input-output functions. The number of decibels above physiological threshold required to generate a 6.0-msec latency response was smaller in the aided when compared to the unaided condition, thus mimicking the electrophysiological finding in “recruiting” patients. Variations in the low-frequency portion of the aid's frequency-response curve produced little change in the evoked response, while increases in its high-frequency cutoff produced shorter latencies. The reliable and systematic relation between subjective sensation, hearing-aid characteristics, and neuro-electrical response appears to warrant the continued investigation of the use of brainstem evoked responses for hearing aid fitting in hearing-impaired populations.

No abstract

No abstract