THE CLASSIC myeloelastic-aerodynamic theory of phonation is based on the belief that the vocal folds, positioned and tensed by the laryngeal muscles, are separated momentarily by air pressure and moved back together by steady muscle pressure plus suction from the moving air (the latter is the Bernoulli or aerodynamic effect1). These forces cause an upward and transverse vibratory cycle of the vocal cords with a frequency identical to that of the sound waves produced. The intensity of the sound is controlled by air pressure, quality by the shape and size of the laryngeal and pharyngeal structures, and pitch within a given larynx by the shape and tension of the vocal folds, all coordinated neurologically.
In 1950, the phoniatrist, Raoul Husson, published the neurochronaxic or neuromuscular hypothesis of vocal-cord vibration that opposed this classic theory.2 Based on studies with laryngeal stroboscopy, Husson stated that the vocal folds are separated
Dedo HH, Dunker E. Husson's TheoryAn Experimental Analysis of His Research Data and Conclusions. Arch Otolaryngol. 1967;85(3):303–313. doi:10.1001/archotol.1967.00760040305013