Analysis Of Disordered Speech of Children with Cleft Palate

Abstract

Speakers with velopharyngeal incompetence,produce hypernasal speech across voiced elements.During the production of vowels,due to the defective velopharyngeal mechanism,oral cavity gets coupled with the nasal cavity.This coupling may introduce resonances of nasal cavity in the resulting vowel sound.Speech signal of eight cleft palate children with various VP opening have been studied. By considering normal and nasal vowel formants of normal speakers as reference, we have observed that variation in the spectrum of their speech occurs due to various types of VP opening due to abnormal coupling of oral and nasal cavity. In case of large VP opening an extra peak or nasal resonance is seen to appear around 600Hz and for small VP opening around 950 Hz. As the VP opening or cut of the cleft palate increases, the first formant reduces and lowers the extra formant.