Effect of nasal decongestion on voice spectrum of a nasal consonant-vowel.

The nasal cavity and its related structures make significant contributions to human phonation, especially the resonance of voice spectra. The voice spectra of the nasal consonant-vowel (CV), [md:], in the subjects with nasal obstruction were obtained and were compared with the spectra of the same CV vocalized by the same subjects after topical nasal decongestion treatment with 1:1000 epinephrine solution. Results revealed that the intensity damping was more marked in the high-frequency area (>1600 Hz) after the nasal decongestion. Moreover, the intensities of the spectral valleys damped more than the spectral peaks, especially the spectral valley of 1000-2700 Hz. Therefore, a more complex spectral pattern was formed by the resultant uneven damping effect after nasal decongestion. The nasal cavity plays an important role in the formation of spectral peaks and valleys, and such engraved voice spectra may also characterize nasal voices like the nasal CV [md:] demonstrated in our study.