Role of perceptual acclimatization in the selection of frequency responses for hearing aids.

Previous work concerning the late-onset auditory deprivation and/or acclimatization effect in adult hearing-aid users has suggested that the benefits of a particular frequency response from a hearing aid may not become apparent until material exposure to that frequency response has been achieved. The generality of that finding was tested further. A group of subjects who were established users (12 to 15 months) of a particular frequency response (limited at high frequencies by the system of provision) were re-prescribed with a theoretically advantageous frequency response according to the NAL prescription. Using a speech-in-noise test (word identification) and a sentence verification test, the benefits of the re-prescription were not (or at best only marginally) evident upon immediate testing but became statistically significant and of material clinical magnitude following experience with the represcription for 8 and 16 weeks. These results suggest that comparative selection regimes and research designs based upon little or no experience of the listening environment through the hearing aid are likely to seriously misrepresent the benefits available to the hearing-impaired listener.