ファイバースコープによる音声器官の動的観測

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For viewing the articulatory movements of speech organs inside the body, we have developed a new technique by use the specially designed fiberscope. There are three types of fiberscopes, the standard model, the thinner model, and the wide-angle model. The former two models were designed for observing the larynx, and the third mainly for observing the pharynx and the velum. All of them are inserted through the nasal passage in order to secure free movements of the articulatory organs during observation. Fiberscopes are basically composed of the image guide, the light guide, the objective lens, and the eye piece(Fig. 1). The image guide is a bundle of aligned("coherent")glass fibers and it transmits the image from one end coupled to the objective lens, to the other end coupled to the eye piece, while the light guide conducts the light for illumination from a light source to the object. The two bundles form a flexible cable of the scope. The diameter of each glass fiber is 9 microns for the image guide and 22 microns for the light guide. In a control unit there is an angle lever to which thin wire is attached and runs to the tip of the flexible cable for the remote bending control of the tip portion. A cine-camera can be attached to the eye piece by means of an adapter. The standard mode, animproved version of the model we first reported in 1968, has an outside diameter of 5. 5 mm at the tip. The objective lens gives an image field angle of 44 degrees, and the object to lens distance ranges from 15 to 50 mm. A light source of 300 W xenon lamp gives sufficient illuminations for the glottis for motion pictures at a rate of, for example, 64 frames per sec. , giving an image size of 6×6 mm^2 on the film. Photographic emulsion of ASA 500 is used. The thinner model which was more recently designed has an outside diameter of 4. 4 mm at the tip. The image size on the film is approximately 4×4 mm^2 when the same adapter as in the standard model is used. In respect to the image resolution, it is somewhat inferior to the standard model. The wide-angle model has an outside diameter comparable with the standard one, the objective lens giving a field angle of 65 degrees and a lens to object distance range of 7 mm to infinity. The image size on the film is designed to be the same as the thinner model. Before the insertion of the scope, a surface anesthesia is applied to the nasal cavity and the epipharynx. Positioning of the scope(Fig. 2 and 8) is quite easy and does not cause any discomfort or disturbance to the subject in performing natural utterances. By visual inspection and some quantitative measurement of the photographic images of the larynx, frame by frame, we can analyze the opening and closing gestures of the glottis as well as the presence or absence of the vocal fold vibration during consonant articulations(Fig. 4). When the vocal pitch is controlled, an apparent change in the distance between the arytenoid and the epiglottis, and the up and down movements of the larynx are usually observable(Fig. 5). A combination of the transillumination technique(photoelectric glottography) with the fiberscopic observation(Fig. 6) provides useful data for detailed analysis of the rapid changes in the glottal conditions(Fig. 7). Some phonetic data of the laryngeal adjustments in speech have been reported elsewhere. Use of the wide-angle model for viewing the pharynx and the velum is now in the stage of preliminary experiment. Results are quite promising. A brief review is also presented on other techniques being employed for observing articulatory movements of the speech organs. The techniques mentioned are:ordinary cineradiography, the new technique of computer controlled tracking of moving objects with use of an x-ray microbeam, the photoelectric(transillumination) method, the ultrasonic measurement, the electrical glottography, and the dynamic palatography.
社団法人日本音響学会の論文
1971-09-10

ファイバースコープによる音声器官の動的観測

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