ACOUSTICAL COUPLING BETWEEN LIP VALVES AND VOCAL FOLDS

In normal speech and singing, the standing waves produced in the upper vocal tract are thought to have relatively little effect on vocal fold vibration. We demonstrate the effect of acoustic waves on vocal fold motion. The waves, whose magnitudes are comparable with those produced by vocalisation, are produced by playing a pipe in the manner of a didjeridu. We monitor vocal fold and lip motion by measuring their electrical admittance through the skin, and compare them with the radiated Sound. In the presence of deliberate vocalisation, interesting heterodyne effects are produced, which are visible in all three signals. When the folds are relaxed, or in the configuration used for whispering, standing waves produced by playing the pipe produce vibrations in the vocal folds whose magnitudes are comparable with those associated with active vocalisation.