THE PERCEPTION OF COMPLEX HARMONIC PATTERNS BY PROFOUNDLY HEARING-IMPAIRED LISTENERS

In providing profoundly hearing-impaired persons with processed speech through a signal-processing hearing aid, it is important that the new speech code matches their auditory capacities. This processing capaci ty for auditory information was investigated in this study. In part 1, the subjects' ability to judge similarities among 8 different but rel ated harmonic complexes was studied. The patterns contained different numbers of harmonics to a 125-Hz fundamental frequency; the harmonics had been spread over the spectrum in various ways. The perceptual judg ments appeared to be based on a temporal cue, beat strength, and a spe ctral cue, related to the balance of high and low frequency components . In part 2, three sets of synthetic vowels were presented to the subj ects. Each vowel was realized by summing harmonically related in-phase sinusoids at two formant frequencies. The sets differed in the number of sinusoids per formant: 1, 2 or 3. It was found that the subjects u sed spectral cues and vowel length for differentiating among the vowel s. The overall results show the limited but perhaps usable ability of the profoundly impaired ear to handle spectral information. Implicatio ns of these results for the development of signal-processing hearing a ids for the profoundly hearing impaired are discussed.