Roger D. Colcord

VOICE ONSET TIME OF VELAR STOP PRODUCTIONS IN AGED SPEAKERS

Voice onset time (VOT) was measured for voiced and voiceless velar stop consonants across three vowel contexts (/i, a, u/) in healthy young adult and older subjects. Analysis showed that mean VOT values for both /k/ and /g/ across the three vowel contexts did not differ between the two groups; however, differences in VOT variability (standard deviation) approached significance; the older subjects exhibited increased variability. This apparent increase in variability may be related to the subtle anatomical and physiological changes with age.

Age-related differences in acoustical aspects of contrastive stress in women.

The purpose of this investigation was to compare the fundamental frequency (F0), durational, and sound pressure characteristics of speech during production of contrastive stress, a suprasegmental component of speech, in young adult and elderly women. Results indicate that, while both groups significantly increased F0, duration, and sound pressure level during production of contrastive stress, elderly women increased F0 to a significantly greater extent than young women and, for all acoustic parameters, the groups were dissimilar in position effects. In spite of the age related differences, such differences did not appear to limit the ability of elderly women to provide linguistic information through prosody. However, they may do so differently from young women. These findings may have implications in terms of treatment of speech disorders in the elderly.

Differential vowel duration associated with children's word-final fricative deletion.

This study assessed whether 3 children, 5 to 6 years old, who deleted word-final fricatives preserve the voicing contrast for those fricatives by producing differential duration of the preceding vowel. The childrens CV syllable productions were compared to their CV(C) syllable productions in which the final consonant was intended but actually deleted. Analysis indicated that all 3 children exhibited significantly longer vowel duration in CV syllables than in CV(C) syllables. This differential duration of the preceding vowel was shown in both isolation and carrier phrase conditions. Of the 3 children 2 preserved the voicing contrast by showing significantly longer vowels preceding voiced consonants as compared to voiceless consonants. One child did this in both isolation and carrier phrase conditions and the other child did this in isolation only. All 3 children manipulated vowel duration to signify the linguistic contrast, therefore these findings support a linguistic perspective of speech development which focuses on the acquisition and knowledge of the linguistic rules of the language. In addition, the large amount of variability in vowel duration for CV and CV(C) syllables and the marked variability in performance across children support a biological view of a developing vocal tract undergoing structural and physiological changes.

Effects of auditory masking by white noise on primary stressing during spontaneous speech

6 adult subjects (3 men, 3 women) produced highly similar spontaneous speech utterances in quiet and with 90-dB SPL white noise. The frequency of occurrence of perceptual judgments of primary stressing in an utterance was not affected by the masking noise. This finding supplements our previous report that variability for stress production of fundamental frequency (fo) during spontaneous speech was preserved under short-term auditory disruption. Also, it adds further support to the contention that fo is under open-loop regulation.

Time Compression and Spectral Characteristics of Phonemes

The present study compared spectral characteristics of the test phonemes of Subtest 13 of Auditory-Visual Abilities Test produced at a normal rate and a 50% time-compression. Results showed marked damping of high frequency energy above 3000 Hz, a by-product of the instrumentation.