抄録
Coarticuration is important in speech recognition or synthesis of connected speech. Therefore, in the study of connected speech, speech unit should be considered from the viewpoint of the coarticuration. In this paper, combination of two phonemes are considered as the unit mentioned above and called a phoneme dyad. The reversibility of phoneme dyad is noticed in this paper to study its nature. Reversible dyad means that we can listen to /sa/ when /as/ is reproduced reversely. Identification experiments have been done for 120 subjects. In these experiments, we analyzed the nature of reversibility of phoneme dyad by taking the following points into consideration: (1) The question is whether the reversibility of phoneme composed of the same consonant can be influenced by the vowel. (2) In case of occurring a confusion, is there any rule? What is the cause for the rule? (3) How does the reversibility of consonant change as to words or meaningless spellings? As a result, the facts mentioned below were found out. Phoneme dyads composed of vowels or /s/ are reversible. Phoneme dyads composed of voiceless stops like /k/ are not reversible. Nevertheless, voiceless stops in a word sometimes can be heard when a word that has been recorded reversely is reproduced reversely. This shows that the information proper to human is important in case of understanding the word. There was a tendency that confusion happens among the phonemes which have the same place of articuration. This tendency is noticeable especially as to stops, and shows that an information at the place of articuration is reversible.
