Essay on phonation

Phonation is defined as a laryngeal motor behavior used for speech production, which involves a specialized coordination of laryngeal and respiratory neuromuscular control. To analyze the process of phonation, the anatomic structures and physiology must be considered. (Loucks et al, 2007).

Voice Sounds. Normal phonation is audible during auscultation, with the intensity and clarity of speech also dissipating from proximal to distal airways. Voice sounds that are more or less pronounced in distal lung regions, where vesicular breath sounds should occur, may indicate areas of consolidation or hyperinflation, respectively.

The larynx is the principal structure for producing vibrations of the air stream, while the oscillating vocal folds are responsible for activating vibrations of the air. The rapid closing and opening of the vibrating vocal folds periodically interrupts the air stream and produces a glottal tone later modified in the cavities of the vocal tract.

The intermediate and deep layers together are about 1 to 2 mm thick (Titze, 1994:15-17; Hirano et al., 1981). Those layers lie on top of the thyroarytenoid muscle (and muscle vocalis3), which is a major part of the vocal folds, being approximately 7 to 8 mm thick.