Evaluation of fatigability of the levator veli palatini muscle during continuous blowing using power spectra analysis.

Abstract

The purpose of this study was to compare the fatigability of the levator veli palatini (LVP) muscle during blowing in speakers who exhibit velopharyngeal incompetence with that from normal speakers by means of power spectra analysis. All subjects were instructed to blow into a tube for more than 10 seconds at maximum possible effort. The LVP muscle activity (electromyography) was sampled at 2 kHz for 10 seconds from the time when the oral air pressure during blowing was stabilized. These samples were subjected to Fast Fourier Transfer analysis with analytic windows of 0.5-second width. The electromyography mean power frequency slope with respect to time for each subject was estimated. Three speakers with repaired cleft palate and three normal speakers were selected as subjects. The slopes of the regression lines for all three subjects with repaired cleft palate were negatively signed with statistical significance (t test, p <.01). The slopes for all of the normal speakers were negatively signed, but these were not statistically significant. These results suggest that the LVP muscle of speakers with repaired cleft palate who exhibit varying degrees of velopharyngeal dysfunction may deteriorate more easily in comparison with the LVP muscle of normal speakers.