As the acoustical standard microphone, the condenser microphone MR-103 had been developed, and the system of acoustical standards in Japan has been established for audible range in air. But there has been no suitable microphone, to be used as the atandard microphone, in the range of higher frequencies, especially in water. The microphone discussed in this paper has crystal plates of the ammonium dihydrogen phosphate as the active elememt, and is prove most suitable fot thestandard microphone considering from its characteristics discussed in detail.
Description of articulation tests on speech transmission systems utilizing two or three bandpass filters which have pass bands approximately corresponding to the bands of formants in Japanese vowels, and articulation scores obtained from the above mentioned tests are shown in this paper. Articulation scores of (1) total sounds, (2) each vowel, (3) each consonant and (4) each syllable, and confusions between vowels and between consonants are shown in the text. The articulation scores of each sound or syllable show different features corresponding to each system, even in the systems of which articulations of total sounds are nealy equal in mean value. Some examples of reelations between the scores of each sound or syllables and the pass bands of systems were obtained. As the scores of each syllable are especially important, thefrequency bands contributing to the articulation of each syllable are discussed here. It provides fundamental data for study on the information bearing elements of speech to establish relation with sound spectrograms of syllable from these results.