A Singer’s Guide to
Vocal disorders
An Outline of the Vocal Mechanism
The human voice is not the result of just the vocal cords that reside in the human throat. Instead, there are three components that make up the vocal mechanism: respiratory, phonatory, and articulatory. Each component of the vocal mechanism is interconnected and vital in any type of voice production. When investigating a vocal disorder, for example, it would be remiss to treat the larynx without considering the respiratory and articulatory constituents.
Respiration:
While quiet breathing is an involuntary action, the process of vocal production requires the controlled act of respiration. Inspiration in mammals is a negative pressure system in which the diaphragm and intercostal muscles of the ribs contract and increase the thoracic volume which pulls air in. Expiration involves the relaxation of diaphragm and the intercostal muscles which pushes air out. During singing, a prolonged, extremely controlled form of this action is undertaken. A singer contracts their diaphragm in such a way that a large volume of air is taken in. This air is then released in an exceptionally controlled fashion tailored to the amplitude and pitch of the note being sung. The abdominal muscles of a trained singer allow for the disciplined support and co-ordination of the diaphragm, abdominal wall, and muscles in the chest in such a way that breathing is controlled.
Figure 1: Inspiration and expiration with a
side view of the respiratory system.
Phonation:
The vocal component responsible for phonation is the larynx. The larynx is an intricate organ made up of a cartilaginous enclosure containing a network of joints and muscles. Its main function is actually not for vocal production, but to prevent of foreign bodies from entering the lungs.
The vocal cords are the most important vibratile component of the larynx. They are located at the top of the trachea and extend like ledges from the side of the larynx.
Figure 2: The top view of vocal cords during
inspiration.
The space between the vocal folds through which air passes is referred to as the glottis. During inspiration, the glottis is wide, as seen in Figure 2., and becomes narrower during expiration without phonation. When expiration is accompanied by speech or singing, the glottis is extremely small and sometimes nonexistent as the vocal folds are brought very close together. This occurs with rapid vertical and horizontal vibration of the vocal folds. It is the rate of these vibrations that establishes the pitch of the notes in singing.
Vocal techniques, such as falsetto and vibrato, are created when trained singers use their vocal folds in special ways. When employing falsetto, the only parts of the vocal folds that vibrate are the ligamentous edges located at the tip of the vocal fold, while the rest of the vocal fold essentially relaxes. This differs from modal, or full, voice, during which the entire vocal fold vibrates. The vocal folds also behave in a unique way when vibrato is produced. The sound heard when a singer uses vibrato is a slight variation in pitch due to free oscillation of the vocal folds. To produce proper vibrato, a singer must open their pharynx while simultaneously closing and relaxing their vocal folds to produce the desired oscillation. Both of these techniques involve complex coordination of the laryngeal muscles.
Talented singers are skilled and experienced at using their larynx to the point where creating a correct pitch or producing vibrato is essentially an unconscious action.
Resonator:
The three resonators of the vocal mechanism are the mouth, the pharynx, and the nasal cavities. When air passes through the larynx during vocal production, a simple buzzing sound is produced. It is the resonators that change that sound into the recognizable voice of a human being. Some experts agree that the resonators are largely responsible for why each human voice is distinct and why some singers are more enjoyable to listen to than others.
Figure 3: An outline from the side of the
resonating cavities of the mouth and
pharynx.
After air passes through the vocal folds it moves through the pharynx, an irregularly shaped tube which connects the larynx to the mouth and nasal cavities. The pharynx and mouth contain cavities that, when adjusted, shape the sounds heard when a person is speaking or singing. It is the work of the muscles of the pharynx and mouth that is essentially responsible for forming all of the words in the human vernacular.
The most important of these muscles include the ones controlling: the upper and lower lips, the tongue, the jaw, the soft palate, and the muscular folds in from the soft palate to the side of the tongue and pharynx. All phonation from the vocal folds is modified and amplified by these muscle-controlled cavities and give us all our own unique vocal sound.
Singing is one of the most common forms of artistic expression among human beings. Singing is a way of life for some and therefore, proper vocal health can be of the upmost importance. From hoarseness to chronic laryngitis, singers are in constant fear for their vocal mechanism. This site outlines various vocal disorders common in singers, how to prevent them, and guidelines to their treatment. This site is strictly informative; do not implement any treatment before consulting either an ENT or otolaryngologist.
