Abstract
The subjects were eight bimaxillary complete denture wearers who noted neither subjective nor objective speech disorders. The mechanism of speech and changes with days were investigated and concurrently compared with that of normal subjects when pronouncing |s| and |∫| by analyzing tongue-palate contacts and speech waveforms.
The results were:
1. On pronouncing CV syllables the preceding consonant duration in denture wearers delayed greatly as compared with normal subjects, but decreased on pronouncing VCV syllables, showing nealy the same value of normal subjects.
2. The following vowel duration in denture wearers was little different from that in normal subjects when pronouncing CV syllables. Although the duration decreased greatly in both groups when pronouncing VCV syllables, the tendency to decrease was greater in denture wearers than in normal subjects.
3. As with normal subjects, the duration from the start of tongue-palate contact to the onset of preceding consonant in denture wearers was short when |a| and |o| were added as preceding vowels, whereas it was relatively long when |i|, |u|, and |e| were added, especially, the duration for |i| was the longest.
4. As is the cases for normal subjects, the duration from the onset of preceding consonant to the indication of so-called standard palatograms in denture wearers became relatively short in the group having the preceding vowel of |i|, whereas it became long in the groups having other preceding vowels.
5. There were no marked changes with days in pronunciation after setting denture at three points of time; namely, at the time of setting denture, after a few days, and after approximately 10 days.
