Evidence of acclimatization in persons with severe-to-profound hearing loss.

The present study examined the phenomenon of acclimatization in persons with a severe-to-profound hearing loss. A secondary purpose was to examine the efficacy of a digital nonlinear power hearing aid that has a low compression threshold with expansion for this population. Twenty experienced hearing aid users wore the study hearing aids for three months and their performance with the study hearing aids was evaluated at the initial fitting, one month, and three months after the initial fitting. Performance of their current hearing aids was also evaluated at the initial fitting. Speech recognition testing was conducted at input levels of 50 dB SPL and 65 dB SPL in quiet, and 75 dB SPL in noise at a +10 SNR. Questionnaires were used to measure subjective performance at each evaluation interval. The results showed improvement in speech recognition score at the one-month evaluation over the initial evaluation. No significant improvement was seen at the three-month evaluation from the one-month visit. In addition, subjective and objective performance of the study hearing aids was significantly better than the participants' own hearing aids at all evaluation intervals. These results provided evidence of acclimatization in persons with a severe-to-profound hearing loss and reinforced the precaution that any trial of amplification, especially from linear to nonlinear mode, should consider this phenomenon.