The effects of rehydration on phonation in excised canine larynges

Experiments using excised canine larynges were conducted to study the restoration of vocal efficiency in dehydrated larynges. Excised larynges were dehydrated with warm, dry air to the point that airflow through the approximated vocal folds would not entrain the folds to produce phonation. The dehydrated vocal folds were then bathed in a saline solution. The rehydrated larynges were then remounted on the bench apparatus that enabled phonation with a constant humidified airflow, and measurements were made of phonation threshold pressure, glottal airflow, and amplitude. Hydration resulted in significantly increased efficiency and decrease in phonation threshold pressure. The findings confirm clinical impressions that hydration is critical in the physiology of normal phonation.