The voice change during, puberty is more dramatic than any other period of human development. At the end of this period, voice change has completed and the qulaity of voice is fixed in both sex. To evaluate these change during puberty, author tried to examine the local findings of the larynx and acoustic analysis of voices of 265 normal males, 175 normal females. Age ranged from 9 to 15 years. And following results were obtained. 1) Fundamental frequency decreased with aging in both sex, and the greatest changes were noted between 13 and 14 years old groups in male and 11 to 12 years old group in female. After age of 14 years, the difference between both sexes was prominent significantly(p<0.05). 2) Sound intensity increased with aging in both sexes. And after age of 13 tears, the difference of both sex was prominent. 3) Maximum phonation time(hereafter, refered to MPT) increased with aging in both sexes, and the greatest change was noted between 14 and 15 years old group in male and between 10 and 11 years old group in female. 4) Vital capacity increased with aging in both sex, and greatest change was noted in between 14 and 15 years old group in male and between 11 and 12 years old group in female. 5) Mutation triangle were found most commonly in male 13 years old group, and the overall incidence was 4.3%. It was characteristic finding in male and resulted in increse in fundamantal frequency and decrease in maximum phonation time due to incomplete closure of vocal cord. 6) Phonation quotient was found high(175ml/sec) in age of 13 years in male, and 191ml/sex in age of 15 years in female. 7) Pubertal voice change started in age of 12 years and completed in age of 15 years in male. In female it started in age of 11 years and completed in age of 13 to 14 years.