Spectral characteristics of speech at the ear: implications for amplification in children.
This study examined the long- and short-term spectral characteristics of speech simultaneously recorded at the ear and at a reference microphone position (30 cm at 0 degrees azimuth). Twenty adults and 26 children (2-4 years of age) with normal hearing were asked to produce 9 short sentences in a quiet environment. Long-term average speech spectra (LTASS) were calculated for the concatenated sentences, and short-term spectra were calculated for selected phonemes within the sentences (/m/, /n/, /s/, [see text], /f/, /a/, /u/, and /i/). Relative to the reference microphone position, the LTASS at the ear showed higher amplitudes for frequencies below 1 kHz and lower amplitudes for frequencies above 2 kHz for both groups. At both microphone positions, the short-term spectra of the children's phonemes revealed reduced amplitudes for /s/ and [see text] and for vowel energy above 2 kHz relative to the adults' phonemes. The results of this study suggest that, for listeners with hearing loss (a) the talker's own voice through a hearing instrument would contain lower overall energy at frequencies above 2 kHz relative to speech originating in front of the talker, (b) a child's own speech would contain even lower energy above 2 kHz because of adult-child differences in overall amplitude, and (c) frequency regions important to normal speech development (e.g., high-frequency energy in the phonemes /s/ and [see text]) may not be amplified sufficiently by many hearing instruments.
Pittman
Andrea L
AL
Boys Town National Research Hospital Omaha, NE 68131, USA. pittmana@boystown.org
Stelmachowicz
Patricia G
PG
Lewis
Dawna E
DE
Hoover
Brenda M
BM
D000328:Adult; D002675:Child, Preschool; D005260:Female; D006310:Hearing Aids; D034381:Hearing Loss / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013018:Sound Spectrography; D013061:Speech Acoustics; D013068:Speech Production Measurement