Speech/voices of mandibular prognathism was analyzed by means of Visi-Pitch, Spectrograph and Nasometer. Separately from these acoustic analyses, cephalograms of articulation gesture during phonation were measured for vocal tract deformatio by
pre
and
postorthognathic surgery.
50 controls with normal stomatognathic function (25 males and 25 females) and 8 patients with mandibular prognathism (4 males and 4 females) were used for these studies.
The speech materials composed to disdochokinetic labial, dental, palatal and velar sounds, Korean vowels /i.e.a.u.o/ and nasal sound preceding and following high vowels /i/.
@ES The results are as follows:
@EN 1. The acoustic intensity of postoperation increased all the speech events in comparison with pre-operation.
2. The pitch in post-operation is higher than in pre-operation. The increment of pitch after operation is related to the laryngeal hight.
3. The total means of frequencies for first formants /i.e.a.u.o/ were lower in post-operation than pre-operation, that for second formants were higher in post-operation than in pre-operation.
4. On cephalogram, the tongue position after post-operation draw back. as a results the aperture and the distance of pharyngeal width were narrower.
5. The Voice Onset Time (VOT) in post-operation decreased after the operation, the incidence of VOT in bilabial consonants showed the glottalization in many cases.
6. The frequency of glottalized fricative sound decreased and that of lateral sounds increased after operation.
7. The nasalance of post-operation is higher than that of pre-operation, and the rate of velopharyngeal closure for post-operation showed the activity in comparison with pre-operation.
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