Acoustic qualities of phonation in young hearing-impaired children

Monosyllables were recorded from a group of 24 hearing-impaired and 6 normal-hearing children between three to six years of age. Tokens of the syllables /ba/ and /bo/ were placed on listening tapes and a panel of 10 experienced listeners made ratings of relative voice quality. The phonation samples were subjected to both a gross (spectrographic) and a fine (computer-aided) acoustic analysis. The following acoustic characteristics were examined: (1) mean fundamental frequency, (2) duration, (3) mean period-to-period changes in intensity and in fundamental frequency, (4) spectral energy ratio above and below 1000 Hz, and (5) intonation contour. The type of intonation contour appeared to be the most important characteristic separating the better from the poorer deaf speakers. The hearing-impaired subjects produced four different types of deviant intonation contours. In addition, two abnormalities of phonation, diplophonia and breathiness, are described.