Voice acoustic analysis of normal Taiwanese adults.

BACKGROUND Because of advances in voice research, voice acoustic analysis including fundamental frequency (F0), sound pressure level (SPL), jitter, shimmer, harmonics-to-noise ratio (H/N ratio), and maximum phonation time (MPT) can now be easily recorded and analyzed with a computer. Because these systems are widely used in clinical practice, this study was designed to establish the normal acoustic analysis parameters in normal Taiwanese adults. METHODS From Mar. 2002 to Dec. 2002, 45 Taiwanese women and 45 Taiwanese men younger than 50 years old were recruited as subjects for this study. The commercially available Computer Speech Lab and Aerophone II system manufactured by Kay Elemetrics Corp. were used to record the aforementioned acoustic data under comfortable phonation. Each gender was separated equally into 3 age subgroups. Then differences between gender and age subgroups were investigated by statistics software SPSS 10.0. Our results were compared with data from previous reports. RESULTS The value of F0 (counting; vowel /a/) was greater for females (203.2 +/- 21.7; 213.4 +/- 25.4 Hz) than for males (118.3 +/- 17.3; 121.3 +/- 16.4 Hz). Conversely, the value of MPT was greater for males (28.0 +/- 9.4 sec) than for females (22.6 +/- 7.6 sec). There were no significant differences in average SPL and jitter between female (77.8 +/- 5.5 dB; 0.66 +/- 0.27%) and male (77.5 +/- 5.5 dB; 0.56 +/- 0.23%) subgroups. Except for shimmer and H/N ratio in the male subgroup, there were no differences in parameters within both gender subgroups with respect to age. CONCLUSIONS We have developed a body of normal data for various parameters of acoustic analysis in different age groups and genders. It seems that the majority of voice characteristics of adults were relatively stable and did not change with aging between 20 and 49. But the shimmer and H/N ratio were variable in different genders and age groups. However, the voice characteristics of adults older than 50 years old were not recorded in this study and therefore require further investigation.