Hirohide Yoshioka

Abnormal articulatory dynamics in a patient with apraxia of speech: X-ray microbeam observation☆

Abstract The temporal organization of articulatory movements in a patient diagnosed as having apraxia of speech was explored by means of pellet tracking techniques using an X-ray microbeam system. The results indicated that the temporal organization among different articulators of the patient was sometimes disturbed in his production of a meaningful Japanese word /deenee/. It was also observed that the pattern and velocity of the articulatory movements of the patient in repetitions of monosyllables were different from those of typical dysarthric patients.

Laryngeal adjustments in the production of consonant clusters and geminates in American English

The glottal opening gesture and its timing control in various sequences of voiceless obstruents were investigated by the combined techniques of electromyography, photo‐electric glottography, and fiberoptic endoscopy. The results obtained at both electromyographic and movement levels revealed that the glottal opening gesture is characterized by a one‐, two‐, or more‐than‐two‐peaked pattern in a regular fashion according to the phonetic nature of the voiceless segments: each voiceless obstruent or geminate accompanied by aspiration or frication noise tends to require a single separate peak of the opening gesture, while an unaspirated stop embedded in a voiceless environment can be produced within the opening gesture attributed to an adjacent aspirated stop or fricative. Such an independent opening gesture of the glottis for the production of voiceless aspirated stops or voiceless fricatives even in sequentially unvoiced contexts can be interpreted as assuring the aerodynamic requirements for turbulent noise production during the aspirated stop or fricative segment.

Interarticulator Programming in Obstruent Production

Most work on speech motor control has been devoted to the spatial and temporal coordination of articulatory movements for successive units, segments or syllables, in the speech chain. An intrasegmental temporal domain has generally been lacking in speech production models, but such a domain is necessary at least for certain classes of speech sounds, e.g., voiceless obstruents, clicks, ejectives. The present paper examines the nature of laryngeal-oral coordination in voiceless obstruent production in different languages using the combined techniques of electromyography, transillumination and fiberoptic filming of the larynx together with aerodynamic and palatographic records for information on supralaryngeal articulations. The results suggest that laryngeal articulatory movements are organized in one or more continuous opening and closing gestures that are precisely coordinated with supralaryngeal events according to the aerodynamic requirements of speech production.

Laryngeal activity in Swedish obstruent clusters

Laryngeal articulatory movements and their coordination with supralaryngeal events have proved to be important for control of voicing and pre- and post-aspiration in obstruents. A reciprocal pattern of activity generally has been observed among laryngeal adductor and adductor muscles in the control of glottal opening in voiceless obstruent production. Current notions about laryngeal articulatory control rest, however, mainly on studies using simple linguistic materials, where voiced and unvoiced segments alternate in a regular manner. The present study examines laryngeal activity in voiceless obstruent clusters using the combined techniques of electromyography, fiberoptic filming, and transillumination of the larynx. The results indicate that laryngeal articulatory movements are precisely coordinated with the oral articulations of clusters to meet the aerodynamic requirements of speech production. Several laryngeal movements may occur in a cluster. Comparison of temporal patterns of glottal area variations obtained by fiberoptic filming and by transillumination of the larynx, showed them to be practically identical.

Intrasegmental timing: laryngeal-oral coordination in voiceless consonant production

Abstract Recent studies of articulatory timing in speech indicate that the relative timing of articulatory gestures may remain constant across changes in stress and speaking rate. Evidence for this kind of temporal invariance has been shown in studies of oral articulators, mostly for gestures associated with adjacent segments in the speech chain. The present study deals with the same problem at the intrasegmental level, i.e., temporal relations between articulatory events within one segment. Temporal coordination of laryngeal and oral articulations in voiceless consonant production was investigated using transillumination and palatography. Voiceless dental stops and fricatives under different stress conditions spoken at two different rates served as the linguistic material. Two speakers of American English participated. Results suggest that temporal ratios between oral and laryngeal gestures tend to remain constant across changes in stress and speaking rate. These findings are consistent with those obtained for other aspects of speech motor control as well as for other types of human motor behavior, suggesting common modes of control.

Laryngeal Activity in Icelandic Obstruent Production

Laryngeal activity in the production of voiceless obstruents and obstruent clusters in Icelandicwas investigated by the combined techniques of transillumination and fiberoptic filming of the larynx. Contrasts of preaspirated, unaspirated, and postaspirated voiceless stops were found to be produced basically by differences in laryngeal-oral timing. In clusters of voiceless obstruents, one or more continuous laryngeal opening and closing gestures occurred depending on the segments in the cluster.Peak velocity of glottal abduction was higher for fricatives than for stops. This, and other differences in laryngeal adjustments and interarticulator timing between stops and fricatives, are most likely due to different aerodynamic requirements for stop and fricative production. The present results further question the usefulness of timeless feature descriptions for modeling speech production.

Laryngeal Adjustments in the Production of the Fricative Consonants and Devoiced Vowels in Japanese

The role of laryngeal adjustments for phonetic variations of voicing in Japanese--vowel devoicing and intervocalic /h/ voicing--was investigated using laryngeal electromyography (EMG) and fiberoptic endoscopy. The results indicated that the vowel devoicing was accompanied by EMG activity patterns of the posterior cricoarytenoid and interarytenoid different from those for fully voiced vowels, causing the glottis to be wide open. In this respect, it may be concluded that vowel devoicing mainly reflects a kind of free variation at a higher level than the EMG signals. In contrast, the voicing of /h/ occurred while the glottis remained as wide as it did for voiceless /h/ or /s/ with comparable EMG patterns of those muscles, despite the presence of vocal fold vibrations. Therefore, it may be that this latter phenomenon is chiefly dependent on some other condition at the level of the glottis.

Scaling of glottal opening.

Laryngeal control occurs mainly along two dimensions. One involves the longitudinal tension of the vocal folds and is used for control of fundamental frequency. The other involves abduction/adduction of the folds. This dimension is used in the vegetative functions of the larynx and in its phonetic function to control voicing and aspiration as well as voice quality. Although fine adjustments in timing of abduction/adduction gestures relative to supralaryngeal events produce contrasts of aspiration in obstruents, variations in the size of these gestures appear to be less significant and less finely controlled. The present experiment explores the control of laryngeal abduction/adduction by examining to what extent speakers can control size of glottal aperture under different conditions, with and without suitable feedback. The results suggest that voluntary control of the size of glottal opening is rather poor, and that subjects are unable to make very fine-graded adjustments along this dimension. Voluntary control of glottal opening in isolation is limited, perhaps because normal activities seldom require separate control of this variable. Instead, control of glottal opening is tightly couples to such other activities as respiration, swallowing and speech articulation. Even in the context of sound production, glottal aperture is poorly controlled, perhaps because the precise degree of opening (as opposed to precise timing of opening and closing) has comparatively little practical significance over a wide range of openings.

Velar movements during speech in two Wernicke aphasic patients

The articulatory gestures of the velum in two Wernicke aphasic patients were examined to compare their performances with those of an apraxic patient by means of the fiberoptic technique. In contrast to the marked variability in the apraxic performance in terms of velum height and segmental duration, the two fluent aphasic subjects showed a relatively high degree of consistency in velar movements throughout several repetitions of nonsense syllables and meaningful words. In addition, both patients exhibited a normal pattern of anticipatory coarticulation. Analyses of the velar movement patterns during the speech-sound error processes of both patients suggested that these errors were not due to an impairment at the level of articulatory programming but to an error in the selection of a target phoneme.

Interaction between Articulatory Movements and Vocal Pitch Control in Japanese Word Accent

In order to investigate the interaction between articulatory and vocal pitch controls, EMGs of the cricothyroid (CT) and sternohyoid (SH) muscles were recorded during utterances of two-mora Japanese words with rising and falling accent types in the Tokyo dialects. The test words consisted of combinations of open and closed vowels. It was revealed that the changes in CT activity were consistently observed in correspondence with the F0 shift according to the accent types, while the SH muscle was observed to be active both for jaw opening and F0 lowering, with some subject-to-subject difference. It was also observed that the time lag between the decrease in CT activity and the F0 fall varied with a shift in the relative timing of SH activity in one subject, but not in the other. Articulatory jaw opening with SH activation was considered to positively contribute to F0 lowering, but the use of this mechanism appeared to be optional at least in the Tokyo accent.