Characteristics of the mouth shape in the production of Japanese

Stroboscopic observation

Abstract

The mouth of a speaker was illuminated by a stroboscopic light source every 10ms, and pictures of both frontal and lateral views of the mouth were taken utilizing a special camera in which a long film was driven continuously. Changes in the dimensions of various parts of the mouth were measured in these pictures. The up-and-down movements of the centers of the upper and lower lips, and the lateral movements of the corners of the lips, were also recorded by attaching small metal pellets to the lips at these points and by illuminating them with the stroboscopic light source every 5ms. The frontal projections of the traces of these points were displayed three-dimensionally by adding the time axis.(This graph is called a “labiogram.”) The material used here comprised the 100 Japanese monosyllables and some words consisted of two, three or four moras. They were spoken by a female adult. On the basis of the stroboscopic observations, characteristics of the mouth shape for each kind of the speech sound and coarticulation effects were analyzed. The use of the visual information of the mouth shape to improve lipreading ability of Japanese was also discussed.