No abstract

The acoustic characteristics of voiceless velar and alveolar stop consonants were investigated for normally articulating and phonologically disordered children using spectral moments. All the disordered children were perceived to produce It/ for /k/, with /k/ being absent from their phonetic inventories. Approximately 82% of the normally articulating children's consonants were classified correctly by discriminant function analysis, on the basis of the mean (first moment), skewness (third moment) and kurtosis (fourth moment) derived from the first 40 ms of the VOT interval. When the discriminant function developed for the normally articulating children was applied to the speech of the phonologically disordered group of children, no distinction was made between the velar and alveolar stops. Application of the model to the speech of individual children in the disordered group revealed that one child produced distinct markings to the velar-alveolar contrast. Variability measures of target /t/ and /k/ utterances indicated greater variability in this disordered child's productions compared with the normally articulating children. Phonological analysis of this child's speech after treatment, in which the velar-alveolar contrast was not treated, revealed target appropriate productions of both It/ and /k/. By contrast, the other three phonologically disordered children, for whom no acoustic distinction was found between target It/ and target /k/, did not evidence any knowledge of the contrast after treatment with other target phonemes.

No abstract

As part of a research program that aims to develop an explicit acoustic basis for a single-word intelligibility test, an initial attempt to characterize the formant trajectories and segment durations of seven test words produced by 30 normal speakers is described. These characterizations are referred to as "acoustic signatures." The data indicate that: (1) formant trajectories show two sex effects, namely, that females are more variable as a group than males and tend to have greater slopes for the transitional segment of the second-formant trajectories and that these effects are consistent across words; (2) Bark transformations of the frequency data do not seem to eliminate the interspeaker differences in formant trajectories, nor do they eliminate either of the sex effects described above; and (3) segment durations have different variabilities depending on the syllabic structure of the word; no sex effect was noted here. The discussion focuses on the appropriate form for the acoustic signatures, as well as factors that should be considered in selecting words for signature development. To demonstrate the potential application of these data, formant trajectory and segment duration data from 18 speakers with amyotrophic lateral sclerosis and varying degrees of dysarthria are compared to the acoustic signature for the word wax.

The results provide preliminary support for the construct and concurrent validities of the Speech Intelligibility Probe for Children With Cleft Palate as a measure of children's speech intelligibility.