7$TH MEETING ß ACOUSTICAL SOCIETY OF AMERICA

from analysis of the characteristics of the sound generated by turbulence in an idealized model of the vocal tract for fricative

consonant production, consisting of an acoustic tube with an adjustable constriction. [-This work was supported in part by a contract from the U.S. Air Force Cambridge Research Laboratories, Office of Aerospace Research, and in part by a grant from the National Institutes of Health.•]

S3. Psychological and Distinctive-Feature Relations of English Consonants. SADANAND SzNCH, Howard University, Washington, D. C.--The interconsonantal relations may be described by presence/absence of distinctive features, which may be transferred into units. Such transfer simplifies de- scriptions ß/b///d/= V1-OICING q- C1-ONSONANTAL q- G•-R•.WTY q-D•-IFFUSENESS/V•-oICING q- C•-ONSONANTAL q- D•IFFUSENESS =G'-•vIT¾. The model was tested using results of ABX. The interconsonantal relationships of some features, e.g., continuant, was found more real than others, e.g., vocalicness. The relations were more real when difference between conso-

nants was of one unit than of two, etc. In the present experi- ment tested was the above model using results of paired com- parison on a one-to-seven-point scale. The 23 consonants of English were recorded in 506 pairs in conjunction with post- consonantal /a/ and presented to 50 native listeners in un- distorted condition and to 50 when tape was played back backwards. Significant correlations were found between inter- consonantal relationships of distinctive-feature measures and the measures obtained by subject's rating in both modes of presentations. The reality of relation against the reality of distinction was confirmed when comparing the relative im- portance of features and places of articulation. Bilabial and palatal places, independently, showed more real relation and alveolar and velar places more real distinction.

S4. Late Responses to Speech Stimuli as Demonstrated by Electroencephalography Utilizing a Summing Computer Technique. HENRY TOBIN •.ND J•.MES T. G•.H•.M (non- member), Case Western Reserve University, Cleveland, Ohio, and Purdue University, Lafayette, Indiana.--In the EEG literature relating to auditory functioning, there is a notable lack of studies in which response to speech stimuli is investigated. It is not inherently certain in what manner speech signals should be presented so that the EEG response can be effectively viewed. This study assumed that the speech signal that could be the most easily controlled and whose parameters could be specified in detail should be the vehicle of initial interest. The purpose of the study was to determine whether speech, con- sidered to be a species-specific function, did in fact elicit different EEG behavior than nonlinguistic signals. The primary problem in the use of linguistic elements was to demonstrate that the EEG response differed in some sys- tematic way from nonlinguistic elements of comparable dura- tion, amplitude, amplitude variation, and rise time. A summing computer was employed in an attempt to identify differences in response parameters that were related to the linguistic relevance of the signal. Unique EEG findings in the after- discharge region as a result of the speech stimulus are reported.

S5. Effect of Pitch Averaging on the Quality of Natural Vowels. A. E. ROSENBERG, Bell Telephone Laboratories, Inc., Murray Hill, New Jersey 07974.•A pitch synchronous analy- sis was carried out over the vowel portions of the CVC utter- ances/hed/,/had/, and/hod/and the stressed vowel portions of the sentence, "Few thieves are never sent to the jug," all recorded by a male speaker. The analysis provided formant frequencies, excitation parameters, and an accurate measure- ment of each pitch period. There were about 40 periods in each of the vowel portions of the CVC utterances and about 20 in each of the stressed vowel portions of the sentence. Each measured period was replaced by a period obtained by averag-

ing adjacent periods over a symmetric "window." Window sizes of 2, 4, 8, 16, 32, and 64 periods were selected. The vowel portions were then resynthesized with the new periods but maintaining all other parameters of the original analysis. Sub- jective evaluation was carried out by means of paired com- parison tests between utterances with different window sizes, including the natural utterances. The results indicate that a relatively large amount of averaging is necessary to detect a difference in quality from the natural utterances.

S6. Voice Timing: Cross-Language Experiments in Identifi- cation and Discrimination. A•T•V• S. A•R•soN, Haskins Laboratories, New York, New York, and University of Connecti- cut, Storrs, Connecticut, XN• LEIGU LIS}•, Haskins Labora- tories, New York, New York, and University of Pennsylvania, Philadelphia, Pennsylvania.•Experiments have shown that listeners' ability to detect differences along some physical continuum of variation appropriate to stop consonants is closely bound up with their assignment of stimuli to linguistic categories. A dimension that we have shown to be used in similar but not identical ways across a large variety of languages for the differentiation of word-initial stops is voice- onset time (VOT), the temporal relation between the onset of glottal pulsing and acoustic features that mark supraglottal articulation. We focus our attention here on English, a language with two stop categories along the VOT dimension, and Thai, a language with three categories. Prevocalic labial, apical, and velar synthetic stops with VOT varying in small steps were produced on the Haskins formant synthesizer. The labeling responses show a good fit between production and perception. Discrimination responses by speakers of the two languages suggest that discriminability is essentially deter- mined by specific language experience rather than by general phonetic categories.

S7. Timing of Glottal Movements in Plosive Production. M•TIN ROTrXEN•E•, Department of Electrical Engineering, Syracuse University, Syracuse, New York.•A model is pre- sented for the primary parameter distinguishing plosive phonemes having the same place of articulation. This param- eter is expressed in terms of the timing between the period of articulatory closure and a maximally fast change in glottal adjustment. For intervocalic plosives, the change in glottal adjustment is "cyclic," either voiced-breathy-voiced, or voiced-open-voiced, and requires at least 100 to 150 msec. In the prevocalic position (after an open glottal adjustment), the change is unidirectional, from open to voiced, except for certain phonoaspirated plosives in which the change is ap- proximately open-voiced-breathy-voiced. The model is unusual in that (1) it is based on the adjustment of the glottis, and not on the actual occurrence of voicing, and (2) it takes into con- sideration the dynamic constraints inherent in changes of glottal adjustment. The adjustment of the glottis can be monitored by bypassing the articulatory closure with a low- resistance air path and recording the resulting air flow. Four intervocalic and four prevocalic categories of timing pattern are described that have the potential of supporting a pho- nemic distinction.

S8. Experiments on Speech Rhythm. GEOl•6•: D. ALLEN, Department of Linguistics, University of California, Los Angeles. •In many studies involving the rhythm of English speech, the onset of the nuclear vowel of a stressed syllable has been in some way identified with the rhythmic beat of that syllable. In our experiments, however, we have found that the relation between vowel onset (VO) and syllable beat depends upon the consonants that immediately precede the stressed syllable, upon the nuclear vowel itself, upon the number of syllables between successive stressed syllables, and upon tempo. In one experiment subjects repeated the sentence "This is the beat in •," in such a way that the stressed syllables in "This,"

The Journal of the Acoustical Society of America

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