口の構えと舌の形が日本語母音明瞭度に及ぼす影響について

Abstract

It has been conventionally believed that a "standard" shape of the resonance cavity exists corresponding to each cardinal vowel. The authors attempted to study the effect of the deviation of the shape of the mouth opening and the position of the tongue, which are the decisive and dynamic elements to form a resonance cavity, from the standard of each vowel, using the following method. Combining the nine shapes of the mouth opening with the five positions of the tongue, forty-five kinds of resonance cavity were set. The speech sounds which were pronounced through these cavities by one male speaker were recorded on tape. The vowel intelligibility of thus recorded speech sounds were investigated. The conclusions were as follows : 1. The position of the tongue, generally, is more significant as the element of vowel articulation than the shape of the mouth opening. 2. The significance of the position of the tongue and the shape of the mouth opening, however, is different among the vowels. For example, in case of vowel /i/ the position of the tongue is essential to produce the vowel. In the other cases, the vowel articulation is more or less influenced by the shape of the mouth opening. 3. All five Japanese cardinal vowels are satisfactorily generated through the reasonance cavity which has adjacent jaws and a mediate mouth opening. This fact indicates that the standard cavities which correspond to each vowel are unnecessory to produce the vowels. 4. Compensation between the position of the tongue and the shape of the mouth opening is observed to exist. 5. In conclusion, among the elements which form the standard resonance cavity of a certain vowel there exist both the essential and the non-essential elements. Hence, the change of the non-essential element within a considerable range does not influence the vowel articulation.