Part 2 : DDiscussion after the lecture some basic problems in clinical research

Abstract

One-hour discussion after the lecture was focussed on rather basic voice problems, a little apart from the clinical problems the author emphasized. They include 3 main topics. 1. The function of the vocal muscle According to recent reports, replacement of the vocal muscle with fat tissue, which was performed for spasmodic dysphonia, demonstrated that a fairly good voice could be obtained. Taking into account the clinical facts together with numerous experimental findings, the discussion tended to be settled at "the vocal muscle may not be essential for phonation but it is probably so for the control of voicing". 2. Model for phonation Various models for phonation were discussed, including the Schoenhaerl, Hirano, Ishiza- ka, and Titze. The Hirano's "body and cover" model is essentially the same as the Schoenhaerl's concept emphasizing the mobility of the mucosa, the author thought. Since it is impossible to define the "body" discretely, whether it means the vocal muscle only or not, it may be misleading sometimes. In Titze's model, the figures for the body in terms of mass, location, and stiffness, is very difficult to assign on the anatomical basis. The only possible means to judge whether the model and hypothetical figures are correct or not would be to examine whether the model output curve matches well with the real vocal output under various physiological conditions. 3. Diplophonia This terminology is sometimes confusing. The voice of vocal fold paralysis is often referred to as diplophonia. But it should be realized that the two different musical tones are not being produced. It is a kind of irregular tone, or hoarseness. The two vocal folds with different tension do not produce two-pitched tone. One vibrating vocal fold per-se cannot be a source of sound in a practical sense. Possibility of producing a sound such as confusing with glottal sound in the articulatory organ was discussed.