1957 年 13 巻 4 号 p. 299-306
In 1951, the late professor Katsumi Imahori has designed a new speech frequency analyzer and named "Phonoscope. " Successive improvements have been made on this instrument with the aim of applying it to the speech correction method for the deaf children, and the investigation on representation of speech sounds for the normal and deaf people has been carried on with this "Phonoscope. " Phonoscope is a kind of direct speech translator, making spoken speech sounds visible by means of position and trace of light-spot on the phosphorescent screen of a cathode ray oscilloscope. The horizontal axis on the screen corresponds to the zero crossing (positive-going) frequency of the partial speech sound passed through a low pass filter with the cut-off frequency of 800 c. p. s. , while the vertical axis corresponds to the zero crossing (positive-going) frequency of the partial speech sound passed through a high pass filter with the same cut-off frequency as the above. The results of the vowel representation by Phonoscope are as follows: (1) The difference of the vowel distribution between adults (20-30 in age) and children (11-13 inage) was partly seen, and the authors were able to set the characteristic region of each vowel on the screen. (2) For the deaf children, the trend was shown that the light-spots representing vowels spoken by the deaf children were located outside the characteristic region for the vowel of normal people, on account of the lack of clearness in their pronunciation. And this trend was shown more strongly with increasing loss of hearing. This result agrees with that of our preliminary test on their aural articulation. (3) So it may be hoped that the Phonoscope will be usable as a means for speech correction in the deaf children.