In an edentulous patient after hemiglossectomy, acoustic characteristics of soundswere studied with and without complete dentures of different morphology. Forms of the denturepalatal plate were changed as follows: 1. normal palatal form 2. augmented form in the anteriorregion 3. augmented form as extensively as tongue, floor of the mouth and lower denture can bein contact with. Acoustic parameters characterised sounds were Formant, Voice onset time, Energy, Spike file and Spectral pattern. They were calculated with a minicomputer by usingliner prediction method and time domain method.
Result
1. Acoustic characteristics after the hemiglossectomy were as follows.
(1) Formants characterised five vowels were similer one another as compared with normalsubjects and five vowels had a tendency to be centralization.
(2) Lingua-alveolar plosive sound (/t/) was mistaken as bilabial sound (/p/).
(3) Lingua-velar plosive sound (/k/) was mistaken as fricative sound (/h/).
2. Improvement in sounds (especially, /i/ line and /∫/ sound) was observed with the augmentedcomplete denture as extensively as tongue, floor of the mouth and lower denture can bein contact with palate.