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PubMed1983

Children's spontaneous and imitative speech: an acoustic-phonetic analysis.

The purpose of this study was to compare the voice onset time of voiced and voiceless stop consonants in children's spontaneous and imitative speech. Ten children (2:3 to 3:8) were recorded producing the same test words spontaneously and imitatively, following a model. There were no statistically significant differences between imitative and spontaneous productions.

Child, Preschool↗
PubMed1985

Phonetic speech perception deficits in dyslexia.

Adult developmental dyslexics showed deficits in the identification of the vowels of English when the sole acoustic cues were steady-state formant frequency patterns. Deficits in the identification of place of articulation of the English stop-consonants [b], [d] and [g] in syllable-initial position were also observed. The average consonantal error rate was 22%. These error rates are significantly different from those of nondyslexic control groups (p less than .01). No single deficit characterized the entire group of dyslexic subjects. The pattern of errors with respect to place of articulation also varied for different groups of subjects. Three dyslexics have high vowel error rates and low consonantal error rates. The data are consistent with the premise that dyslexic subjects may have different perceptual deficits rather than a general auditory deficit involving the rate at which they can process perceptual information. The clinical histories of the present subjects suggest genetic transmission of these speech perception deficits. The presence of genetic variation in the biological substrate relevant to the perception of human speech should be further explored.

Adolescent↗
PubMed1985

Phonetic inventories, 15-24 months: a longitudinal study.

Longitudinal samples of meaningful speech of 34 normally developing children were analyzed to determine the range and types of consonantal phones produced at 15, 18, 21, and 24 months. Separate inventories for word-initial and word-final consonants were constructed for each child at each age level. Group analyses showed that early inventories in initial position were composed primarily of voiced anterior stops, nasals, and glides; by 24 months, voiceless stops, velars, and a few fricatives were also included. In final position, inventories consisted primarily of voiceless stops and alveolar consonants. There was a strong tendency for the voiced stops to appear first in initial position and for [t] and [r] to appear first in word-final. Individual analyses of place and manner of articulation revealed highly similar patterns across subjects. The findings are related to other longitudinal research in early phonological development and to studies of babbling of younger subjects and correct productions of older subjects.

Child Language↗
PubMed1987

Movement timing in deaf and hearing speakers: comparison of phonetically heterogeneous syllable strings.

We review evidence suggesting that deaf speakers do not move their articulators toward the following open posture throughout closure and report results from a preliminary cinefluorographic study. Two prelingually deaf and two hearing speakers produced two different strings of alternating heterogeneous monosyllables as though speaking in time with a metronome (the so-called P-center task). Events traditionally associated with vowel production appeared evenly timed throughout the productions, and, in general, the deaf speakers performed similarly to the hearing speakers. We relate the results to Fowler's (1983) interpretation of the P-center phenomenon as an indicant of continuous vowel production.

Adult↗
PubMed1992

Acoustic-phonetic contrasts and intelligibility in the dysarthria associated with mixed cerebral palsy.

This study evaluated the relationship between specific acoustic features of speech and perceptual judgments of word intelligibility of adults with cerebral palsy-dysarthria. Use of a contrasting word task allowed for intelligibility analysis and correlated acoustic analysis according to specified spectral and temporal features. Selected phonemic contrasts included syllable-initial voicing; syllable-final voicing; stop-nasal; fricative-affricate; front-back, high-low, and tense-lax vowels. Speech materials included a set of CVC stimulus words. Acoustic data are reported on vowel duration, formant frequency locations, voice onset times, amplitude rise times, and frication durations. Listeners' perceptual assessment of intelligibility of the 16 dysarthric adults by transcription and rating tasks is also presented. All but one acoustic contrast was successfully made as evidenced by measured acoustic differences between contrast pairs. However, the generally successful acoustic contrasts stood in marked contrast to the poorly rated intelligibility scores and high error percentages that were ascribed to the opposite pair members. A second analysis examined the contribution of these acoustic features towards estimates and prediction of intelligibility deficits in speakers with dysarthria. The scaled intelligibility was predicted by multiple regression analysis with 62.6% accuracy by acoustic measures related to one consonant contrast (fricative-affricate) and three vowel contrasts (front-back, high-low, and tense-lax). Other measured contrasts, such as those related to contrast voicing effects and stop-nasal distinctions, did not seem to contribute in a significant way to variability in the intelligibility estimates. These findings are discussed in relation to specific areas of production deficiency that are consistent across different types of dysarthria with cerebral palsy as the etiology.

Adult↗
PubMed1994

Effects of phonetic context on audio-visual intelligibility of French.

Bimodal perception leads to better speech understanding than auditory perception alone. We evaluated the overall benefit of lip-reading on natural utterances of French produced by a single speaker. Eighteen French subjects with good audition and vision were administered a closed set identification test of VCVCV nonsense words consisting of three vowels [i, a, y] and six consonants [b, v, z, 3, R, l]. Stimuli were presented under both auditory and audio-visual conditions with white noise added at various signal-to-noise ratios. Identification scores were higher in the bimodal condition than in the auditory-alone condition, especially in situations where acoustic information was reduced. The auditory and audio-visual intelligibility of the three vowels [i, a, y] averaged over the six consonantal contexts was evaluated as well. Two different hierarchies of intelligibility were found. Auditorily, [a] was most intelligible, followed by [i] and then by [y]; whereas visually [y] was most intelligible, followed by [a] and [i]. We also quantified the contextual effects of the three vowels on the auditory and audio-visual intelligibility of the consonants. Both the auditory and the audio-visual intelligibility of surrounding consonants was highest in the [a] context, followed by the [i] context and lastly the [y] context.

Adult↗
PubMed2002

Acoustic phonetics in a clinical setting: a case study of /r/-distortion therapy with surgical intervention.

Acoustic measures are used to document the speech of a 6-year-old child with persistent /r/-distortion through several treatment interventions. The child originally presented a complex of speech disorders and was treated by a speech-language pathologist using phonological process techniques. The procedures successfully corrected most of his speech problems, although /r/ remained severely distorted. The primary acoustic manifestation of this distortion was a high third formant. Surgical correction of a banded lingual frenulum, along with adenoton-sillectomy indicated for sleep apnea, is shown to have had a small effect in lowering the third formant. A dramatic change was seen on reintroduction of therapy, when an extreme drop in third formant frequencies for /r/ was observed. The acoustic data are interpreted using speaker-internal controls derived from a dialect-appropriate adult model.

Articulation Disorders↗
PubMedDate not supplied

Darkness in [l] as a scalar phonetic property: implications for phonology and articulatory control.

Dorsopalatal contact and F2 data for speakers of dialectal groups with dark [1] (Majorcan Catalan, Eastern Catalan) and clear [l] (German, Catalan from the València region) provide some support for the hypothesis that degree of velarization or pharyngealization in the alveolar lateral consonant does not proceed categorically but gradually across dialects. Indeed, F2 frequency data for [l] in the context of [i] reveal that darkness does not distinguish the two dialectal groups but varies gradually from dialects with a very dark realization of [l] (Mallorqui) to those with a very clear realization (Valencià) through dialects exhibiting intermediate degrees of darkness (Eastern Catalan, German). A similar scenario applies to the [a] context. This finding questions the complex, two-gestural status of dark [l] and the notion that dark [l] should always be more coarticulation resistant than clear [l].

Electrophysiology↗
PubMed2000

The rhyming skills of deaf children educated with phonetically augmented speechreading.

Two experiments investigated whether profoundly deaf children's rhyming ability was determined by the linguistic input that they were exposed to in their early childhood. Children educated with Cued Speech (CS) were compared to other deaf children, educated orally or with sign language. In CS, speechreading is combined with manual cues that disambiguate it. The central hypothesis is that CS allows deaf children to develop accurate phonological representations, which, in turn, assist in the emergence of accurate rhyming abilities. Experiment 1 showed that the deaf children educated early with CS performed better at rhyme judgement than did other deaf children. The performance of early CS-users was not influenced by word spelling. Experiment 2 confirmed this result in a rhyme generation task. Taken together, results support the hypothesis that rhyming ability depends on early exposure to a linguistic input specifying all phonological contrasts, independently of the modality (visual or auditory) in which this input is perceived.

Belgium↗
PubMed1994

A PET study of cognitive strategies in normal subjects during language tasks. Influence of phonetic ambiguity and sequence processing on phoneme monitoring.

We previously demonstrated using PET in normal subjects (Démonet et al., Brain 1992; 115: 1753-68) that, by comparison to a reference task of monitoring for pure tones, a phoneme monitoring task involving two factors of complexity (sequence processing and perceptual ambiguity) activated Wernicke's area and Broca's area. In the present experiment, we explored the respective influence of these factors on brain activation. In addition to the reference task, four phoneme monitoring tasks in non-words were used with stimuli presented binaurally. These included an easy, non-sequential, unambiguous task; a perceptually ambiguous, but non-sequential task; a sequential, but perceptually unambiguous task; a sequential and ambiguous task identical to the one we used in our previous study. Changes in regional cerebral blood flow were measured in nine right-handed volunteers using PET and infusion of H2(15)O. The sequential unambiguous task was associated with the same pattern of activation as that observed for the equivalent non-sequential task, i.e. activation of Wernicke's area. The two tasks with perceptual ambiguity gave rise to activations in the left fusiform gyrus and in Broca's area, respectively. Activation of the left fusiform gyrus in the perceptually ambiguous but non-sequential task suggests a prominent role for a strategy involving phoneme-to-grapheme transcoding in subjects, who thereby attempted to visualize non-words that they could not decipher auditorily. Activation of Broca's area in the sequential and ambiguous task reproduces our previous result and suggests that subjects resorted to a predominantly verbal rehearsal strategy when performing this task.

Adult↗
PubMed2004

Intracortical responses in human and monkey primary auditory cortex support a temporal processing mechanism for encoding of the voice onset time phonetic parameter.

This study tests the hypothesis that temporal response patterns in primary auditory cortex are potentially relevant for voice onset time (VOT) encoding in two related experiments. The first experiment investigates whether temporal responses reflecting VOT are modulated in a way that can account for boundary shifts that occur with changes in first formant (F1) frequency, and by extension, consonant place of articulation. Evoked potentials recorded from Heschl's gyrus in a patient undergoing epilepsy surgery evaluation are examined. Representation of VOT varies in a manner that reflects the spectral composition of the syllables and the underlying tonotopic organization. Activity patterns averaged across extended regions of Heschl's gyrus parallel changes in the subject's perceptual boundaries. The second experiment investigates whether the physiological boundary for detecting the sequence of two acoustic elements parallels the psychoacoustic result of approximately 20 ms. Population responses evoked by two-tone complexes with variable tone onset times (TOTs) in primary auditory cortex of the monkey are examined. Onset responses evoked by both the first and second tones are detected at a TOT separation as short as 20 ms. Overall, parallels between perceptual and physiological results support the relevance of a population-based temporal processing mechanism for VOT encoding.

Animals↗