A STUDY OF THE INFLUENCE ON PHONATION WHEN MAXILLARY ANTERIOR TEETH ARE MISSING

상악 전치부 결손이 발음에 미치는 영향에 관한 연구

This study was performed to investigate the phonetic alterations with upper anterior teeth were missing. To compare the changes of the phonations, before and after insertion of the temporary prosthesis, six subjects who lost their upper anterior teeth were selected (2-male, 4-female). Tested sounds (/ga(가), na(나), da(다), ra(라), sa(사), ja(자), cha(차), ta(타), pa(파), ha(하), gi(기), ni(니), di(디), ri(리), si(시), jl(지), chi(치), ti(티), pi(피), hi(히), seu(스), se(세), so(소), su(수)/were programmed into an IBM AT with and without temporary prosthesis. These experiments were analyzed by formants, consonants durations, and energy level changes with an LSI speech work station program. During the pronunciation of the tested sounds (with and without temporary prosthesis), mandibular movements were recorded to a Mandibular Kinesiogram and analyzed . The findings led to the following conclusions: 1. Objective differences could not be found. However, in every informant, subjective improvement could be noticed. 2. There were no persistant correlations of the formant's changes. And in every informant, phonetic changes were variable. 3. There were various changes of the consonant durations in every informant. By and large, those of /si(시), jl(지), chi(치), Pi(피), hi(히)/ were longer than other tested sounds. After insertion of the prosthesis, durations were shorter. Consonants with /i(ㅣ)/ were longer than with /a(ㅏ)/, with or without prosthesis. 4. With and without temporary prosthesis, mandibular movements were various in the frontal view. Mandibular movements showed lateral deviations, and mandibular positions with /si(시), ji(지), ti(티), seu(스), hi(히)/ were nearer to the mandibular rest position. 5. The kinds of temporary prosthesis and conditions of the missing teeth influenced every informant variously, so there were no correlation between informants. 6. Energy levels increased in all tested sounds with a fixed temporary prosthesis. And, there were no differences between before and after insertion of a removable temporary prosthesis. However, sibilant sounds, and consonants with /i(ㅣ)/ showed a little increased energy level.