Spectral characteristics of hypernasality in maxillectomy patients

To reveal the acoustic characteristics associated with hypernasality and to ascertain their correlation to the severity of hypernasality, 30 speech sa mples produced by 15 maxillectomy patients were acoustically analysed with and without an obturator prosthesis in place. The isolated, sustained Japan ese vowel /i/ was used as the stimulus for acoustic measurement and percept ual judgment to evaluate the severity of hypernasality. Normalized 1/3-octa ve spectral analysis demonstrated the spectral characteristics of hypernasa lity, as a rise in amplitude between the first and second formants around t he 1 kHz region, and a reduction in amplitude of the frequencies higher tha n the second formant. High correlation was shown between the perceptual rat ings and the predicted values derived from stepwise regression analysis.