Spectral Characteristics of Children’s Voices: Variation in SPL
E Stathopoulos, J Huber
This investigation studied the mechanisms used by children to control vocal intensity variation. Aerodynamic and vibratory factors including subglottal pressure, vocal fold closed times, and closing forces affect glottal airflow waveform. While children have an overall higher OQ than adults, they do not use a decreased OQ to increase their vocal intensity. It was hypothesized that children control SPL by increases in subglottal pressure and faster closing forces, incrementally more than adults. The acoustic result was that children produced high SPL by accentuating the higher spectra to a greater degree than adults. One hundred and eighty normal-speaking participants (ten males and ten females, aged 4, 6, 8, 10, 12, 14, 16, 18, and 20-30 years) produced a sustained vowel [a] and syllable trains of [pa] at comfortable pitch and loudness and at 10 dB above comfortable. Measurements included: SPL, Ps, OQ, MFDR, and amplitude of F0, F1, and F3. Data verified young children did not use a decreasing OQ as a mechanism for increasing SPL, but instead increased Ps and MFDR to a greater degree than adults. The formant data substantiated that younger children’s spectra contain more energy in the higher frequencies than do the older children and adults. Results will be discussed relative to the anatomical and physiological differences between children and adults which necessitate different control mechanisms.