Effects of spectral content on Horii Oral-Nasal Coupling scores in children.
Two groups of subjects, one with normal speech and one with hypernasal speech, spoke while hearing their voices unfiltered, low-pass filtered with cut-off frequencies of 1000, 500, and 300 Hz and high-pass filtered with cut-off frequencies of 500, 1000, and 2000 Hz. Measurements of nasalization were made with a miniature accelerometer attached to the side of the subject's nose. Both groups of subjects decreased nasalization when hearing their voices low-pass filtered with a cut-off frequency of 300 Hz. This decrease was statistically significant. The results were interpreted as supporting the hypothesis that nasalization is under feedback control.