The effects of five voice characteristics on LPC quality

Most published evaluations of LPC systems use only one or two speakers. Since LPC quality and intelligibility are known to depend on the speaker, this is an inadequate test of a synthesis system. We recorded eight men and nine women chosen from a speech data base of 81 speakers who were independently rated by two phoneticians for the presence or absence of the following voice characteristics: nasality, harshness, creak, whisper, and pitch extreme. The 17 talkers represented a balanced sample of strong positives or negatives of the five voice characteristics. Each speaker was recorded on one fifty word set from the Modified Rhyme Test. Monosyllabic word intelligibility tests were administered to 88 listeners (with four listeners per speaker set). Results from the intelligibility tests for different speakers show that vocal characteristics and resultant LPC quality are linked. Nasality and whisper are the most strongly correlated with a decreased LPC intelligibility.