Effects of FE modelled consequences of tonsillectomy on perceptual evaluation of voice

This study aimed to investigate the effects of a tonsillectomy on the perceived overall voice quality and timbre. Computer simulations of five Czech vowels were made, including both the calculated resonance effects of large tonsils (size 1.6 cm) and the resonances without tonsils. The simulations were made using a finite element model of the vocal tract, based on magnetic resonance images. The size and shape of the tonsils were ascertained from clinical data. The generated pressure outputs were transformed into sound records presented to 10 trained listeners. Formant frequencies of the simulated samples were measured. The samples with and without tonsils did not differ significantly from each other in voice quality. F3 was significantly lower and the timbre was darker without tonsils. Thus, the effects of tonsillectomy on voice may be perceptible, at least in the case of large tonsils. The effect, however, may disappear in time due to changes in the tissue and due to compensatory changes in articulation.