The effects of expansion on the objective and subjective performance of hearing instrument users.

The present study investigated the effects of expansion on the objective and subjective performance of 20 hearing instrument users fitted binaurally with digital ITE products. Objective performance was evaluated in quiet using the Connected Speech Test and in noise using the Hearing in Noise Test. Subjective performance was evaluated in two ways: (a) by having each participant rate their satisfaction regarding the amount of noise reduction they perceived in each expansion condition on a daily basis and (b) by having each participant indicate which expansion condition they preferred following the completion of a two-week trial. Results indicated that expansion significantly reduced low-level speech perception performance; however, satisfaction and preference ratings significantly increased when using expansion. The effect of degree of hearing loss, expansion kneepoint, and expansion ratio on the effectiveness of expansion for a given listener was discussed.