[Comparison between children with missing anterior deciduous teeth and posterior deciduous teeth by analysis of speech sounds].

Growing human offsprings are creatures that communicate by language. If rapidly growing children lose their deciduous teeth very early in life, their language and pronunciation functions may be seriously affected. The authors conducted a series of tests to find how the voice changes when deciduous teeth are extracted. The results may be summarized as follows. 1. There was no significant difference in the formants of vowels on "a-gyo", the first line of the Japanese syllabary, but an appreciable difference was recognized between children (four to six years old) with missing anterior teeth and posterior teeth when there were consonants before and after these vowels. 2. In the formants of the vowels, there was a marked difference in the vowel "i" when children were fitted with no appliance. 3. The strength of voice components in each frequency range was compared between children with missing anterior teeth and posterior teeth. It differed widely in "o ka a sa n" (which means "Mother") and "a-gyo", when children were fitted with no appliance. These findings indicate that the pronunciation of "o ka a sa n" and "a-gyo" can be recovered to some extent if the children are provided with an appliance. However, a sound analysis indicates that their pronunciation ability of sounds on "ka-gyo", "sa-gyo" and "ta-gyo" (the second, third and fourth lines of the Japanese syllabary) can hardly be fully recovered.