The effect of a carrier phrase on hearing aid amplification of single words in quiet

Objective: A common method to assess the functional benefit of hearing aids is by measuring the performance-intensity curve of single words in quiet with and without hearing aids. Currently, virtually all hearing aids use signal processing, which may have a marked effect on gain as a function of time. Thus, hearing-aid behavior may be different for a word presented in isolation compared to the same word preceded by a carrier phrase, which is a closer replication of natural conversation. The present research was conducted to assess this difference. Design: In a hearing-aid test box, speech materials were routed through hearing aids and the output was recorded with a 2cc coupler. Study sample: Seven different hearing aids were programmed according to the manufacturer's fitting rules, using a given hearing loss. Results: Depending on the hearing aid, and the hearing-aid setting, differences in the overall level of the hearing-aid processed words ranged from -1.5 to 3.5 dB. Differences were due to slow attack times in amplitude compression. Conclusions: Although differences were small for most hearing aids, the use of a carrier phrase should be considered in speech intelligibility tests to ensure that hearing-aid performance closer reflects that in real life.