Characterization of raised phonation in an evoked rabbit phonation model.
OBJECTIVE
Our laboratory has developed an in vivo rabbit model to investigate the effects of phonation on expression and turnover of the vocal fold extracellular matrix. As a logical outgrowth of this research to include phonotrauma in the present study, we investigated the hypothesis that an increase in airflow rate delivered to the glottis produces a change in glottal configuration and an increase in mean phonation intensity.


METHODS
Prospective animal study.


METHODS
Six New Zealand white breeder rabbits weighing 3 to 5 kg were used in this study. A rigid endoscope and camera were used to document glottal configuration. Acoustic signals of modal and raised phonation were recorded and digitized. Two separate one-way repeated measures analysis of variance (ANOVA) tests were used to investigate within subject differences in phonation intensity and fundamental frequency between modal and raised phonation.


RESULTS
Phonation intensity was 54.19 dB SPL (6.21 standard deviations [SD]) during modal phonation, and 60.31 dB SPL (5.68 SD) during raised phonation. Endoscopic images revealed a convergent glottis, with greater separation of the vocal folds during raised phonation. Results of ANOVA revealed a significant within subjects effect for phonation intensity (P = .011). Pairwise comparisons revealed that phonation intensity increased significantly during raised phonation, compared to modal phonation (P = .008). No differences in mean fundamental frequency were observed between phonation conditions.


CONCLUSIONS
Improved understanding of factors that control phonation output in the in vivo rabbit model will result in improved capabilities to match phonation dose across animals and provide immediate direction to future biochemical studies.
Department of Otolaryngology, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee 37232-4480, USA.
Erik R
ER
Swanson
Davood
D
Abdollahian
Tsunehisa
T
Ohno
Pingjiang
P
Ge
David L
DL
Zealear
Bernard
B
Rousseau
D000704:Analysis of Variance; D000818:Animals; D003413:Cricoid Cartilage; D004724:Endoscopy; D005109:Extracellular Matrix / Q000502:physiology*; D010699:Phonation / Q000502:physiology*; D011446:Prospective Studies; D011817:Rabbits; D013961:Thyroid Gland; D014827:Vocal Cords / Q000293:injuries / Q000502:physiology*