Generation and dissipation of heat in vocal fold tissue

The power dissipated in the vocal folds during phonation results from viscous loss in the fold tissues and can be estimated on the basis of a simplified representation of the geometry and movement of the folds. Assuming this power is converted into heat, it combines with the effects of muscle contraction, blood perfusion, and thermal conduction to the surface of the folds to determine fold temperature. To isolate the thermomechanical source of heat, the vocal folds of excised larynges were vibrated vertically over a range of frequencies and amplitudes, while the temperature rise in them was measured by inserted fine-wire thermocouples. The temperature rise observed was somewhat smaller than that predicted. This may be partly accounted for by convective and evaporative cooling of the vocal fold as it moved relative to the ambient air. Future studies should consider the time course of heating and vocal fold geometry in more detail.