No abstract

This study was designed to examine the status of voice onset time (VOT) in identification and production of word-initial voiced and voiceless labial, apical, and velar stop consonants for 20 English-speaking adults. Synthetic speech stimuli were constructed for four continua including BEES/PEAS, BEAR/PEAR, DIME/TIME, and GOAT/COAT. VOT values for 30 productions of the same words examined in the identification task were determined from spectrographic measurements. Analyses of the perceptual data revealed significant differences among labial, apical, and velar stops for the VOT 50% crossover and lower and upper limits of the phoneme boundary, but not for boundary width. In production of voiced and voiceless stops, reliable differences for mean VOT were shown between all cognates and among places of articulatory constriction within voicing category. The latter finding was primarily related to the labial/velar comparisons. Variability among individual speakers was demonstrated in the percentage of voiced stops associated with VOT values in the lead portion of the continuum, whereas all subjects evidenced productions in the short lag range. Comparisons between identification and production demonstrated high consistency for VOT characteristics in that few productions coincided with the perceptual phoneme boundary or contrasting voicing category.

No abstract

Spontaneous speech samples of 27 children with trisomy-21 type Down’s syndrome and 66 normal children were tape-recorded and analyzed for mean fundamental frequency, standard deviation, and range. Results indicate that the mean speaking fundamental frequency (SFF) level for the sample of children with mongolism was significantly higher than the mean SFF level for the control sample. Approximately 50% of the children with mongolism had mean SFF levels exceeding the highest mean SFF level of their matched controls. In only two cases did the mean SFF for a child with mongolism fall below the mean SFF level for control children of the same age and sex. No child with mongolism exhibited a mean SFF level below the lowest mean SFF for any control subject. The subject in question is the clinical observation that children with mongolism typically have low voice fundamental frequency levels.

Voice-onset-time (VOT) measurements were obtained from the productions of three adult females under the following conditions: (1) adult-directed conversation; (2) child-directed conversation; and (3) recitation of citation forms. VOT values were derived directly from frequency-by-time wide-band spectrograms by three independent judges. Results indicate adequate reliability to within 5 msec was obtained among the judges on all spectrograms. Significant differences were noted among and within the three conditions. These results are discussed in terms of current theories concerning parental roles in the infant's acquisition of language.