Failure to change from the higher pitched voice of preadolescence of the lower pitched voice of adolescence and adulthood is called "mutational dysphonia". The voice is weak, thin, breathy, hoarse, and mono-pitched. If the voice theraphy was
failed,
surgery to lower vocal pitch which is refered to thyroplasty type III, is indicated. We compared the post-op acoustic parameters with pre-op data in unilateral antero-posterior shortening of the thyroid cartilage method and bilateral
antero-posterior
shortening of the thyroid cartilage method cach other. Bilateral antero-posterior shortening of the thyroid cartilage method shows significant drop of fundamental frequency and speaking fundamental frequency statistically than unilateral
shortening
method. There was no significant differences in Jitter, Shimmer, SNR, MFR, and other psychoacoustic analysis parameters between two group. These data shows that unequal tension of the vocal cord in uilateral antero-posterior shortening of the
thyroid
cartilage method does not control the pitch effectively so bilatreal shortening method in Type III chyroplasty is recommandable procedure in surgery of the mutational dysphonia.
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