Impact of topical anesthesia on acoustic characteristics of voice during laryngeal telescopic examination.

Objective: The purposes of this study are to investigate the impact of topical anesthetic alone and with concurrent laryngeal telescopic examination on acoustic characteristics of vocal fold function. Comparison with phonation in controlled conditions may imply diagnostic information from the examination.

Methods: Thirty males evaluated as having a normal voice were included in the study. The subjects were asked to phonate sustained /i/ with a naturally comfortable pitch and loudness in three consecutive experimental sequences as "control condition," "anesthetic condition," and "telescopic condition." Acoustic analysis of fundamental frequency, jitter, shimmer, and harmonic to noise ratio in the three different conditions were executed.

Results: The mean and standard deviation of Fo in control condition, anesthetic condition, and telescopic condition were 130.1 +/- 18.5 Hz, 125.7 +/- 19.7 Hz, and 173.2 +/- 35.1 Hz, respectively. The telescopic condition showed more negative change than that in control condition and anesthetic condition in other parameters. There was a significant difference (P < 0.001) between control condition and telescopic condition in all four parameters.

Conclusions: This study showed that anesthesia has little effect on voice performance for subjects with a normal voice. On the other hand, the acoustic characteristics changed significantly during telescopic performance. When doing interpretation of acoustic data, the abnormality of the acoustic characteristics might be the result of the procedures and not reflect vocal pathology. Laryngeal variations due to manipulation of telescope should be ruled out.