[Prosthetic application of digital processing of speech signals]

The purpose of this study was to investigate the acoustic characteristics of the nine sounds, /sa/, /si/, /ka/, /ki/, /ci/, /hi/ and /ri/, which were reported affected by wearing complete denture, through the acoustic analysis of speech samples uttered by nine male subjects. Spectrum analysis was done within the frequency range of 0 to 10 KHz according to the auto-correlation method of liner predictive coding (LPC) analysis. Results 1. The consonant parts of /sa/, /si/, /ci/ and /hi/ wee characterized by the spectrum envelopes and their peak frequencies derived from the LPC analysis of order 5. 2. The consonant parts of /ka/ and /ki/ were characterized by their first spectrum peak frequencies derived from the LPC analysis of order 10. 3. The consonant part of /ri/ was characterized by the spectrum envelope derived from the LPC analysis of order 24, and the sound waveform. 4. The frequencies of the formants (F 1, F 2, F 3) of the following vowels /i/ were derived from the LPC analysis of order 24. They were influenced by individual variations and preceding consonants. 5. Each sound had its own characteristics in the duration of the consonant and of the closure interval and the time from the end of preceding vowel to the beginning of the following vowel.