Regulatory mechanism of register, pitch and intensity of voice in singing was studied in professional singers. The present investigation employed electromyographic recordings of laryngeal muscles' activity and ultra-high speed cinematography of vibrating vocal cords.
The register of voice is regulated chiefly by the vocalis muscle. The heavier the register is, the stronger the contraction of the vocalis muscle is. The lateral cricoarytenoid and interarytenoid muscles assist the vocalis muscle in regulating the register. Thus, the heavy register is associated with thicker vocal cords, more marked mucosal waves, a longer closed phase and a greater speed quotient than the light one. The cricothyroid, as an antagonist of the vocalis muscle, has influences upon the register, but it is not a primary register agent.
In general, activity of the tensors and acductors of the vocal cords increases with increasing pitch. At high pitches in the light register, however, the contribution of these muscles in pitch regulation is less.
At low pitches in the heavy register the intensity of voice is controlled mainly by adductors, whereas the intensity is regulated chiefly by respiratory muscles at high pitches in the light register.
Register, pitch and intensity of voice are not independent parameters in the living humans.
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