The purpose of this study was to obtain normative data for acoustic analysis of voice. Four acoustic parameters, pitch perturbation quotient (PPQ), amplitude perturbation quotient (APQ), normalized noise energy for 0 to 4 kHz (NNEa) and normalized noise energy for 1 to 4 kHz (NNEb) were measured in sixty normal subjects (thirty males and thirty females). The subjects uttered /e/ vowel three times at the comfortable pitch and loudness level. Each sample was acoustically analyzed with the use of Rion SH-10. Intra-subject variation was small in the majority of the subjects but a few subjects presented large variations. The distribution of the measured values of NNEb differed significantly between the males and females whereas that of the other three parameters did not differ significantly between the two sexes. The normal limit (p < 0.05) was 0.43% for PPQ, 1.71% for APQ and20.4 dB for NNEa in both sexes. The normal limit for NNEb differed between men and women ;-9.8 dB for men and-4.4 dB for women. Values greater than these limits should be regarded to be abnormal.
