CANDIDATES FOR MULTIPLE FREQUENCY-RESPONSE CHARACTERISTICS

This study examined what types of subjects may benefit from the use of multiple memory hearing aids that offer variation in their frequency response characteristics. Thirty subjects with varied degrees and conf igurations of hearing loss compared an individually prescribed frequen cy response (NAL) and two variations in which the real-ear response sl ope was either increased (more high-frequency emphasis) or decreased b y about 3 dB/octave over the range from 500 Hz to 4000 Hz. The evaluat ions consisted of paired comparison judgments of pleasantness and of e ase of understanding speech, in quiet and in three background noises w ith substantially different acoustic spectra (traffic noise, speech ba bble, and high-frequency noise). Twelve of the 30 subjects selected di fferent frequency responses for different background noises and/or for different response criteria. These subjects were characterized as hav ing the more severe high-frequency hearing losses (averaged across 200 0, 3000, and 4000 Hz). They also tended to be those for whom the three frequency responses provided the greatest variation in real-ear low-f requency gain. (Despite substantial electronic variations, some subjec ts received only small variations in real-ear gain at the low frequenc ies). When subjects chose a different response for different condition s, they tended to prefer responses for which the slope was negatively related to the spectrum of the stimulus. This was true for both respon se criteria. The conclusion is that hearing aid users with substantial high-frequency losses, and who can be fitted with sufficient variatio n in the low-frequency real-ear gain, have the potential to benefit fr om having a choice of frequency response characteristics.