Effects of different frequency response strategies upon recognition and preference for audible speech stimuli

The purpose of this study was to examine whether the amount of low- versus high-frequency amplification should change as a function of input level, as is done in some recently developed hearing aids. Adults with high-frequency sensorineural hearing loss served as subjects. Both identification performance and preference judgments for audible CV syllables were assessed as a function of input level for three different signal processing conditions both in quiet and in noise. The first signal processing condition was a conventional high-pass frequency response that did not change its transfer function as the input level increased; the second condition was similar to a typical adaptive frequency response (AFR) hearing aid: a high-pass frequency response that became increasingly high-pass as the input level increased; the third condition was similar to the K-Amp hearing aid recommended by Killion (1988): a high-pass frequency response that became more broadband as the input level increased. Results indicated no significant differences among the three different processing conditions for syllable recognition and a strong listener preference for the syllables presented via the conventional amplification scheme.