Hajime Hirose

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 Gestures in Speech Production

This chapter describes the physiological mechanisms of laryngeal gestures for various phonetic distinctions in speech production. An orientation toward the basic laryngeal gestures is presented in Section II, and detailed experimental data are discussed in Section III.

High-speed Digital Imaging of Vocal Fold Vibration

A new method of digitally imaging vocal fold vibration using a solid-state image sensor attached to a conventional camera system is reported. The obtained image signals are stored in an image memory in combination with a personal computer through a high-speed A/D converter. The maximum frame rate for analysis is 4000 fps. After storage of data, images can be reproduced and displayed on a monitor screen as a form of slow-motion display. The system has proved useful for clinical examination of pathological vocal fold vibration.

High-speed digital image analysis of vocal cord vibration in diplophonia

Abstract Simultaneous recording of vocal fold vibrations and speech signals were performed with three patients having diplophonia using a high-speed digital image recording system developed by the present authors. All three cases studied (1 case of unilateral paralysis of the recurrent nerve; 2 cases of unilateral paralysis of external branch of the superior laryngeal nerve) showed a difference in the vibratory frequency between the left and right vocal folds. The phase difference between the vocal cords varies with time. When it reaches a certain threshold, the phase difference is reset and the vocal cord movements resumes synchrony. When the movements of the vocal cords are in phase, glottal closure is complete and the excitation pattern in the speech waveform is strong, whereas when the movements are out of phase, glottal closure is incomplete and the excitation pattern is weak, resulting in a quasi-periodic vibration in speech waveform.

Clinical observations on 600 cases of recurrent laryngeal nerve paralysis.

A statistical review was made on 600 cases of recurrent laryngeal nerve paralysis who visited the authors clinic during the last 16 years. The yearly incidence, the age and sex distributions and the classifications of the causes of paralysis were presented and discussed. A special attention was given to the topics of associated laryngeal paralysis, bilateral recurrent laryngeal nerve paralysis and the so-called epidemic paralysis. A brief comment was also made on diagnosis and treatment of recurrent laryngeal nerve paralysis in general.

Laryngeal control for voicing distinction in Japanese consonant production.

The aim of the present study was to investigate the laryngeal adjustments for voiced versus voiceless distinction in Japanese consonant production by means of laryngeal electromyography (EMG) and fiberoptic observation. Multichannel EMG recordings were taken of a Japanese subject and the data were computer-processed to obtain the averaged activity patterns of the five intrinsic laryngeal muscles with special reference to the voicing distinction in consonant production in various phonetic environments. It was found that there were apparent reciprocal patterns in the posterior cricoarytenoid (PCA) and the interarytenoid (INT) in terms of significant negative correlation, and active control of PCA for voicelessness was demonstrated. The patterns of the thyroarytenoid and the lateral cricoarytenoid were different from that of INT even though these two muscles are usually classified as the members of the adductor group, and their activity levels were apparently influenced by the phonetic environment. A possible contribution of the cricothyroid (CT) to the voicing distinction was also pointed out but further investigations on acoustic parameters seem to be mandatory in more critical interpretation of CT activity in speech.

Vocal-auditory functions of the chimpanzee: consonant perception

The perception of consonants which were followed by the vowel [a] was studied in chimpanzees and humans, using a reaction time task in which reaction times for discrimination of syllables were taken as an index of similarity between consonants. Consonants used were 20 natural French consonants and six natural and synthetic Japanese stop consonants. Cluster and MDSCAL analyses of reaction times for discrimination of the French consonants suggested that the manner of articulation is the major determinant of the structure of the perception of consonants by the chimpanzees. Discrimination of stop consonants suggested that the major grouping in the chimpanzees was by voicing. The place of articulation from the lips to the velum was reproduced only in the perception of the synthetic unvoiced stop consonants in the two dimensional MDSCAL space. The phoneme-boundary effect (categorical perception) for the voicing and place-of-articulation features was also examined by a chimpanzee using synthetic [ga]-[ka] and [ba]-[da] continua, respectively. The chimpanzee showed enhanced discriminability at or near the phonetic boundaries between the velar voiced and unvoiced and also between the voiced bilabial and alveolar stops. These results suggest that the basic mechanism for the identification of consonants in chimpanzees is similar to that in humans, although chimpanzees are less accurate than humans in discrimination of consonants.

The Roles of the Posterior Cricoarytenoid and Thyropharyngeus Muscles in Whispered Speech

In order to clarify the nature of the physiological adjustment for the production of whispering, physiological studies were conducted on the glottal and supralaryngeal adjustments during whispering. The results indicate that for the production of whispering there is a necessary relationship between glottal adjustment and supralaryngeal adjustment in terms of the coordination between posterior cricoarytenoid muscle (PCA) and thyropharyngeus muscle (TP). Also, there might be a function switch in our brain which enables the speaking mode to change from ordinary to whispering, using the activation of PCA and TP, as a result of human evolution.

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.

Simultaneous high-speed digital recording of vocal fold vibration and speech signal

A new method for the high-speed digital recording of the vocal fold vibration is presented. The method employs a solid endoscope, a solid-state image sensor and a digital image memory. About 100 frames of continuous image data with 50 × 50 picture elements can be stored in the image memory at one time. Image recording at a rate of 2000 frames per second was achieved using a small light source of a 250 W halogen lamp. The method enables to record the speech signal without special consideration on the camera noises, and also to observe the recorded image on the spot through CRT display. An example of the image data with simultaneously recorded speech and EEG signals are presented comparing the male and female voices, and the chest voice, falsetto and breathy voice.