Nasal sounds are normally produced with an opened velopharyngeal part during pronouncing nasal consonants. Various disorders in nasal cavity and paranasal sinus can affect the resonance of nasal sounds, and result in change of nasality
perceptually.
Many instruments including rhinomanometry and acostic rhinometry can assess the nasal passage dynamically and statically, but cannot assess the extent of nasality objectively. Recently, analytic methods with computerized equipments such as
Nasometer and
sound spectrogram are gaining wide attention to evaluate the nasality objectively.
In this study, we assessed nasality using Nasometer and sound spectrogram in patients with multiple nasal polyposis before and after endoscopic sinus surgery. With Nasometer, we measured nasalance which reflect the ratio of acoustic energy output
from
the nasal and oral cavities of the speaker. Nasogram slope scores were also measured for bilabial, alveolar, and velar nasal consonants. In the patients with multiple nasal polyposis, nasalance for mamma passage and nasogram slope scores for all
nasal
consonants were significantly lower than normal persons before surgery. After operation, nasalance and nasogram slope scores were significantly increased more than preoperative value. It seems to reflect the widened nasal passway after operation.
On the
sound spectrographic analysis, slight decrement of fundamental frequency of first nasal formant with increased amplitude was noted in all nasal consonants after operation. However, no significant change was noticed in fundamental frequency of
second
nasal formant.
In conclusion, Nasometric and sound spectrographic analysis are considered to be useful tools for objectively assessing the extent of nasality (rhinophonia) before and after operation in the patients with nasal airway obstruction. (Korean J
Otolaryngol
38:7, 1995)
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