Fundamental frequency and amplitude perturbation in reconstructed canine vocal folds

A submucosal fat autograft was implanted within the cover of injured vocal folds of 5 dogs. The implant occurred 6 weeks after unilateral mucosal excision had been performed. Three months postoperatively the larynges of these animals were excised and their phonation was compared to that of normal dog larynges and to other larynges with mucosal excision (but without fat grafting). Radiated acoustic pressure from the artificially driven larynges was recorded and digitized at 20 kHz with 16-bit resolution. Amplitude and fundamental frequency perturbations were extracted from a segment of phonation to assess the stability of the acoustic signals from the 3 groups. It was found that fat augmentation after mucosal excision reduced amplitude and frequency perturbation measures. There was no significant difference between fat-augmented and normal vocal folds. The acoustic measures were also positively correlated with phonation threshold and phonation efficiency measures reported earlier. The results suggest that submucosal fat autograft implantation within an injured vocal fold cover can restore not only the "ease" of phonation, but also the stability of phonation, which is a component of vocal quality.