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Discusses the production of some isolated vowels in ten random orders by a seasoned phonetician. Recording of the acoustic signals and frontal views; Lipreading effect; Audiovisual speech perception.

Focuses on the voicing in speech sounds. Assessment of the acoustic and articulatory bases of the voiced-voiceless difference; Association of harmonic patterning and vocal fold vibration; Selection of the interval over voicing determining the phonetic unit described as voiced or voiceless.

Presents a letter to the editor on aspiration of English.

Focuses on the importance of the voice onset time (VOT) in discussing the phonetic feature of stop voicing. Basis for separating homorganic stop categories across a variety of languages; Limitation of the VOT measure; Relation between burst and pulsing onset.

The search for the acoustic properties useful to the listener in extracting the linguistic message from a speech signal is often construed as the task of matching invariant physical properties to invariant phonological percepts; the discovery of the former will explain the latter. These phonological percepts are essentially the phonemes of pregenerative phonology, and they are more or less faithfully reflected in standard alphabetic writing. Thus English deep and doom are supposed to be perceptually identical in their initial /d/s; the orthographic similarity is in agreement with the linguist's ''representation'' of these forms. The partial identity in spelling is only weak evidence for perceptual invariance, however. First, while some phonemes may comprise a single ''sound,'' others are said by linguists to include phonetically distinct ones. Thus English /p/ includes both aspirated and unaspirated voiceless labial stops. The view that it is not the phoneme, but rather the phonetic feature, to which an acoustic invariant might be attributed, raises two questions: (a) Since segments sharing a feature are rarely judged to constitute a single sound, the search for a feature-specific invariant, whose function is to explain perceptual constancy, is deprived of its essential motivation, and (2) there is no more reason to expect the acoustic cues to a feature to be context-independent than is the case with the phoneme. What seems more likely is to find that some phonemes, and some features, are more invariantly marked in the speech signal than others. [ABSTRACT FROM AUTHOR]

Discussion of voicing as a distinctive property of English stop consonants in initial position has centered on the measure of ''VOT,'' the time of onset of laryngeal signal relative to the noise pulse generated by the stop release, but it has been shown that listeners' selection of |b,d,g| vs |p,t,k| responses to synthetic stop+vowel stimuli is not determined entirely by VOT. Significant effects have been reported to depend on the behavior of the first formant (F1) frequency immediately following voice onset, and on this basis it has been suggested that a ''feature detector'' responsive to a rapidly shifting F1 better explains the infant's discrimination of the two stop categories than some mechanism which measures VOT directly. The relative importance of VOT as against the presence versus absence of F1 frequency shift after voice onset is assayed in several synthesis experiments in which VOT and F1 configurations are systematically varied. Labeling data obtained indicate that varying VOT regularly effects a significant change in listeners' judgments, and that varying F1 has some effect too, but this latter variation is neither necessary nor sufficient generally to shift judgments decisively from one stop category to the other. The data further suggest that the presence of an F1 rising transition after voice onset serves as a voiced-stop cue not so much because of its dynamic aspect, but simply because its onset frequency is low, i.e., at a value appropriate to a closed or almost closed state of the oral cavity. Subject Classification: 70.30, 70.20, 70.70. [ABSTRACT FROM AUTHOR]

Examines the air pressure in the production of stops in English phrases. Variation in intra-oral pressure; Mean peak pressures of /p,t,k/ and /b,d,g/; Implication for the differences in the mean peak pressures.

The article presents an analysis of duration of periods and glottal articulation changes between the release of the word closure and voice onset time in English as considered in phonetics. For quotation type of words the stop closure is distinct, creating a greater time interval which helps distinguish the two phonemes clearly. In normal course of speech, the stop closure is not complete, leading to a smaller interval time and even overlapping along the dimension of voice onset time. In case of a stressed syllable or the syllables in final sentence, stress tends to create a longer voicing lag. The role of contextual features responsible for apparent overlap of dimension along the voice onset time in running speech needs to be explored further.

The article explores the discrimination of durations of silence with and without phonemic significance. Discrimination of an acoustic variable was measured when, as part of a synthetic speech pattern, that variable cued a phonemic distinction and when the same variable appeared in a non-speech context. With stimuli that vary along a single dimension like, of frequency, intensity, or duration, one typically finds that subjects discriminate many times more stimuli than they can identify absolutely.

It has been found to be extremely difficult to isolate phonemic elements from recorded utterances or to synthesize speech by assembling prerecorded phonemic segments. One reason for the difficulty lies in the fact that the perceptually discrete phonemes are typically combined, and in some cases encoded, into units of essentially syllabic dimensions. As a result, prerecorded elements must, in many cases, approximate syllables, and the synthesis of speech by this means will require a large inventory of recordings. By taking advantage of knowledge about the acoustic cues for speech perception, however, it is possible to write rules for synthesis in terms of phonemes (rather than syllables) and thus reduce considerably the number of separate rules or items needed. Indeed, one can reduce the number of rules still further by writing them at the level of subphonemic dimensions, viz., place and manner of articulation. Several complicating factors make it impossible to achieve an ideal minimum. First, rules or rule modifiers must be added to take care of certain prosodic and positional variations. Failure to do so not only affects naturalness, but also impairs intelligibility, even at the level of segmental phonemes. Second, it is necessary in a few special cases to have different rules for a single consonant phoneme (or a dimension of that phoneme) before different vowels. This reflects the occasionally complex relation between phoneme and articulation on the one hand and sound output on the other; presumably, this complication would not affect the rules of synthesis for an articulatory model. A system of rules for synthesis framed largely in terms of subphonemic dimensions is described with reference to an example. Words and sentences of rather high intelligibility have been synthesized by such rules. [ABSTRACT FROM AUTHOR]