The vocal tract from the glottis to the lips is considered to he a resonator and 
the voice is changeable depending upon the shape of the vocal tract. In this 
report, we examined the change in pharyngeal size and acoustic feature of voice 
after tonsillectomy.
METHODS: Subjects were 20 patients. The distance between both anterior pillars 
(glossopalatine arches), and between both posterior pillars (pharyngopalatine 
arches) was measured weekly. For acoustic measurements, the five Japanese vowels 
and Japanese conversational sentences were recorded and analyzed.
RESULTS: The distance between both anterior pillars became wider 2 weeks 
postoperatively, and tended to become narrower thereafter. The distance between 
both posterior pillars became wider even after 4 weeks postoperatively. No 
consistent changes in F0, F1 and F2 were found after surgery. Although there was 
a tendency for a decrease in F3, tonsillectomy did not appear to change the 
acoustical features of the Japanese vowels remarkably. It was assumed that the 
subject may adjust the shape of the vocal tract to produce consistent speech 
sounds after the surgery using auditory feedback.