Long-term and short-term characteristics of speech: Implications for hearing aid selection for young children

This study examined the effects of distance and postural position of both parents and children on the long-term and short-term spectral characteristics of speech produced by the parents. Thirty children (ages 2 months to 3 1/2 years) and their parents (30 mothers and 15 fathers) participated. Third- octave band and overall levels of the long-term average speech spectrum (LTASS) for each speech sample were analyzed in three postural positions and a 1-meter reference condition for each age category. Short-term spectral characteristics of three phonemes (/s/, /∫/, /t∫/) also were analyzed. Results show that typical levels at the input to a child's hearing aid microphone may be as much as 20 dB higher than those found in face-to-face adult conversation. Furthermore, the spectral shape may deviate substantially from an idealized version of the LTASS. Results of the short-term analysis reveal that the peak levels of the three selected phonemes often exceed the LTASS by more than the 12 dB that is often quoted to represent the 1% rms levels of speech in relation to the long-term average. Implications of these results for specific hearing losses are discussed.