Showing papers on "Voice published in 1979"

Passive vocal tract enlargement during voiced stops

Abstract: Voiced stops should become devoiced within 5 to 10 m of stop closure if there is no vocal tract enlargement to delay the inevitable reduction in transglottal pressure drop. Since stops may be voiced longer than this, some cavity expansion must take place, either passive through tissue compliance or active through larynx lowering and the like. To estimate the duration of voicing in stops when only passive enlargement occurs, subjects produced isolated nonsense words of the form VC:V, where V was one of a variety of English vowels and C: was an artificially prolonged /b/, /d/, or/g/. Oral air pressure was vented through a catheter leading from the pharynx to the atmosphere via the nasal cavity. At unpredictable times, a solenoid‐activated valve closed the catheter and the consequent build‐up of oral pressure extinguished the voicing. Voicing continued after this closure longer during /b/ than /d/ or /g/, and longer when coarticulated with high vowels than with low vowels. These results can most plausibly be explained by reference to differences in compliance of the surfaces on which oral pressure impinges during the various consonants and vowels. [Supported by NSF and NIH.]

Acoustic correlates of some phonetic categories.

Abstract: Some of the acoustic properties that distinguish one speech sound from another are reviewed. The point of view is that the auditory system responds to sounds with different acoustic properties in distinctive ways, and that these special responses play an important role in selection and classification of the inventory of sounds that are used in language. Examples of several of these acoustic properties are discussed and illustrated, including the presence or absence of rapid spectrum change, abruptness of amplitude change, voicing and aspiration, and gross spectral properties relating to place of articulation for consonant and vowels.

Relative amplitude of aspiration noise as a voicing cue for syllable-initial stop consonants.

Abstract: The present experiments demonstrate that amplitude of aspiration noise (relative to the following periodic portion of the vowel) is a cue for the distinction between voiced and voiceless syllable-i...

The Acquisition of the Voicing Contrast in Spanish: A Phonetic and Phonological Study of Word-Initial Stop Consonants. Papers and Reports on Child Language Development, No. 16.

Abstract: This paper reports on the acquisition of the voicing contrast in Mexican–Spanish word-initial stops. In Study 1, three monolingual children were recorded every two weeks for seven months, beginning when the children were about 1; 7. In Study 2, four monolingual children about 3; 10 were recorded once or twice. Two analyses were done. Instrumental analysis of the stop productions revealed that not even by age 3; 10 were the children consistently distinguishing between voiced–voiceless stop cognate pairs on the basis of adult-like voice-onset time characteristics. The spirantization analysis, however, more clearly revealed the children's phonological knowledge. Discussion focuses on the implications of the data for phonological development in general and for the phonological description of voicing in Spanish.

The modification of speech perception and production in second-language learning

Abstract: Seventy-two native Spanish speaking children enrolled in programs to teach English as a second language and 24 monolingual English children were tested in speech perception and production tasks with the purpose of determining whether or not there is learning at the phonetic level during second-language acquisition. Performance with the phonetic feature voicing was studied by means of measuring changes in the perception and production of the acoustic property voice onset time. Variables of interest across Spanish-speaking subjects were degree of exposure to English and age. Age was the only group variable for the English-speaking subjects. Results with the Spanish-speaking children showed significant changes in both perception and production of voicing towards the English monolingual pattern. Age had a significant effect in production, but not in perception. It was concluded that learning at the phonetic level does occur during second-language acquisition.

Dimensions in the perception of fortis and lenis plosives.

Abstract: The analysis of the production of fortis and lenis plosives in German has shown the importance of the duration ratio vowel/ (vowel + closure) for the distinction. To complement these results a perception test was carried out in which 29 native speakers identified a randomised sequence of 220 stimuli from tape as one of the phrases ‘Diese Gruppe kann ich nicht leid(e)n (leit(e)n)’. The stimuli were obtained from the two naturally produced originals by changing the ratios and the length of voicing in the plosive through computer processing. The test results indicate very conclusively that judgment can be reversed simply by changing the ratio to the appropriate ones found in production. There is a hierarchy of perceptual dimensions: duration ratio > formant transition > voicing.

Acoustical and perceptual characteristics of speech produced with an electronic artificial larynx.

Abstract: Five normal‐speaking adult males were taught to produce speech using an electrolarynx. Speech phoneme intelligibility was measured in a closed‐set word discrimination test and through phonetic transcriptions of the spoken materials. Mean percentages of correct identification for the five talkers were 90% and 57% for the word‐identification test and phonetic transcription, respectively. An analysis of perceptual confusions revealed that errors were most frequently associated with the voicing feature and that few manner or place of articulation errors occurred. Over the range of variables observed, the intensity of both the speech and the noise radiating directly from the electrolarynx, the spectrum of the radiated noise and speaking rate were not found to be determinants of intelligibility.

Analysis of stop consonant production errors in developmentally dysphasic children

Abstract: The speech production skills of 12 dysphasic children and of 12 normal children were compared. The dysphasic children were found to have significantly greater difficulty than the normal children in producing stop consonants. In addition, it was found that seven of the dysphasic children, who had difficulty in perceiving initial stop consonants, had greater difficulty in producing stop consonants than the remaining five dysphasic children who showed no such perceptual difficulty. A detailed phonetic analysis indicated that the dysphasic children seldom omitted stops or substituted nonstop for stop consonants. Instead, their errors were predominantly of voicing or place of articulation. Acoustic analyses suggested that the voicing errors were related to lack of precise control over the timing of speech events, specifically, voice onset time for initial stops and vowel duration preceding final stops. The number of voicing errors on final stops, however, was greater than expected on the basis of lack of differentiation of vowel duration alone. They appeared also to be related to a tendency in the dysphasic children to produce final stops with exaggerated aspiration. The possible relationship of poor timing control in speech production in these children and auditory temporal processing deficits in speech perception is discussed.

A phonetic analysis of consonantal devoicing in children's speech

Abstract: A number of phonologists have observed the frequent occurrence of ‘devoiced’ obstruents in word-final position in children's utterances. Although such transcription-based accounts have provided evidence of the phenomenon, physical phonetic properties of devoiced consonants have not been described. Therefore, characteristics of voicing control for ‘voiced’ and ‘voiceless’ stops produced by five English-speaking children aged 2; 6–3; 0, five aged 4; 0–4; 6, and five adults were investigated in terms of (1) the percentage of all stop productions evidencing ‘devoicing’ during consonant closure, and (2) in the case of devoiced stops, the proportion of consonant closure evidencing voicing. Both groups of children revealed substantial amounts of consonantal devoicing when compared with the adults; in addition, the proportion of stop closure evidencing voicing was considerably less for the children than for the adults. It was also observed, however, that the children's ‘devoiced’ stops revealed significantly more voicing than their phonemically ‘voiceless’ stop productions.

An effect of phonetic environment on voicing control mechanisms during stop consonants

Abstract: There are abundant data which show the vocal folds to be abducted during closure for intervocalic /p,t,k/ in American English. Vocal‐fold abduction during such stops is reliably indicated by a rapid rise in intraoral pressure following oral occlusion. Recent recordings of intraoral pressure during an adult male English‐speaker's productions of labial and alveolar stops in a variety of environments suggest, however, that vocal‐fold abduction is characteristic only for voiceless stops which precede vowels. Synchronous recordings of intratracheal pressure showed during the closures of stops in all environments that the driving pressure for speech remained appreciably greater than atmosphere. But, during the closures for voiceless stops occurring initially in certain medial consonant clusters, and utterance finally, intraoral pressure generally did not rise above atmosphere. These facts together suggest that /p,t/ in these latter environments were voiceless by virtue of interruption of transglottal flow at the glottis. [Work supported by NSF grant BNS 77‐07686.]

Final Voicing and Vowel Length in Welsh

Abstract: The great majority of Welsh word-final plosives are devoiced lenes (fully voiced before a following vowel or sonorant), with a long vowel preceding. There are also a certain number of words – nearly a

Distinctive feature use in speech perception of children.

Abstract: For adults, the time required to judge whether two phonemes are "same" or "different" has been shown to vary inversely with the number of features on which the phonemes contrast. The present study measured the choice reaction time (CRT) judgments involving all possible pairs of 12 selected English consonants by five-, six-, and seven-year-old children. The same inverse relationship between CRT and feature contrasts typical of adults was exhibited by the children as a group. However, feature profile differences were exhibited according to sex and age. In addition, a multidimensional analysis (INDSCAL) of the proximity judgments as reflected by the CRTs was performed to determine the specific dimensions used by the children. A six-dimensional solution revealed the following perceptual strategies as the bases of their judgments: sibilant frequency, continuancy, voicing, stop, place of articulation, and age of acquisition or markedness.

Consonant intelligibility of speech produced by dyadic rule synthesis

Abstract: We measured the intelligibility of speech generated by a speech synthesis system which converts text to sound by rules. The synthesis process uses dyadic concatenation and is intended for automatic voice answerback in telephone directory assistance situations. The intelligibility of initial and final consonants in monosyllabic words was measured. For comparison two other conditions were tested: PCM‐coded speech (12 bits, 10‐kHz rate) and LPC‐resynthesized speech 02 parameters).The overall percentage correct score for initial and final consonants, averaged over the 33 listeners, was 93.0% and 92.8% for PCM‐coded speech, 86.5% and 85.4% for LPC‐resynthesized speech, and 58.2% and 73.5% for rule‐synthesized speech. Each word list was preceded by two practice runs consisting of one example word for every initial or final consonant. After this very short training phase, the subjects showed no more learning during the actual word list. The voicing character of initial voiced fricatives was not well represented ...

The duration of stop consonants

Abstract: It is well known that the duration of a stop consonant in the intervocalic, poststressed position may serve as a cue to that stop's voicing characteristic [L. Lisker, Lang. 33, 42–49 (1957)]. More recent research has suggested that when stop‐closure durations are examined in a variety of positions, the voiceless stops have greater duration than the voiced stops only in the intervocalic, poststressed position [L. Lisker in A. Valdman [Ed.], Papers in Linguistics and Phonetics to the Memory of Pierre Delattre, 339–343 (1972)]. The present research was designed to provide additional data on stop‐closure durations as a function of (1) voicing, (2) stress, (3) vowel context, and (4) place of articulation. Six subjects produced a series of nonsense disyllables of the form CVCVC in a carrier phrase; for each disyllable, one consonant was a “test consonant” and the other two were controls. The test consonant was systematically varied with respect to voicing, stress and position‐in‐disyllable. Vowels in the disyllable were also varied systematically within the stressed syllable, and included /i/, /l/, u/, and /ae/. Preliminary analyses show that for some subjects, the dorsal stops are affected by stress and position differently than are the apicals and bilabials.

Automatic thresholding for voicing detection algorithms

Abstract: Automatic voicing-decision algorithms depend on thresholds which are dependent on speaker, channel, S/N ratio, etc. Low-frequency energy (LFE) is one of the best voicing statistics when properly thresholded; it is even better if two thresholds are set, one for onset of voicing and one for offset. Two schemes are proposed for adaptive, estimation of thresholds. The first is finding stretches that are "surely" voiced or unvoiced, finding boundaries by heuristic algorithms, and setting thresholds consistent with these boundaries, in the second, one finds segments that are "surely" voiced or unvoiced according to voicing statistics other than LFE, using these to form estimates of the distribution of LFE in voiced and unvoiced cases. Both schemes successfully determine speaker-dependent thresholds in about 15 seconds, during which "standard" thresholds can be used. Overall voicing error rate using LFE with adaptive thresholds is about 1%.

Fundamental frequency as a cue to postvocalic consonantal voicing: Some data from perception and production

Abstract: Several recent studies by Lehiste have reported that changes in fundamental frequency (F0) can serve as a cue to perceived vowel length and, furthermore, that the perceived lengthening of the vowel can influence perception of the voicing feature of stop consonants in syllable-final position. In Experiment 1, we replicated Lehiste’s basic results for stop consonants in final position. Experiment 2 extended these results to postvocalic fricatives. The final consonant in syllables of intermediate vowel duration was more often perceived as voiced when F0 was falling than when F0 was monotone. In Experiment 3, we examined the F0 contours produced by eight talkers before postvocalic stop consonants and fricatives in natural speech for minimal pairs of words differing in voicing. The amount of change of F0 over the vowel was no greater before voiced than voiceless consonants, suggesting that the earlier perceptual effects cannot be explained by appealing to regularities observed in the production of F0 contours in vowels preceding postvocalic consonants.

Devoicing of word‐final stops

Abstract: A process devoicing stops in word‐final position is common among languages and is evidenced in Appalachian and Black English. Attempts to explain this phenomenon, however, have been unsuccessful. For example, generative phonology, which accounts for change by rule‐addition, rule‐loss, and rule‐reordering, is purely descriptive. Likewise, natural phonology, which claims that change occurs when a child fails to master a phonetic opposition, never explains under what conditions “failure” occurs. Instead, devoicing may be explained in terms of the voicing cues for post‐vocalic stops. (1) Voicing is signalled by the manner in which the preceding vowel is terminated. (Termination is defined in terms of the period of vocal cord vibration during the transition from vowel to stop.) [F. Parker, J. Phonetics 2, 211–221 (1974).] (2) The cue for a post‐vocalic voiced stop is perceptually weaker than that for its voiceless counterpart. (Evidence comes from error detection studies and phonological change.) Thus, devoici...