The pharynx consists of three parts: the nasopharynx the region between the soft palate and the back of the nasal cavities; the oropharynx the region between the soft palate and the hyoid bone and the hypopharynx, the region between the hyoid bone and the vocal folds. In anatomical terms the throat usually refers to both the oropharynx and hypopharynx.
The throat performs three important functions 1) swallowing 2) forming an air passage between the nose, mouth and larynx and 3)shaping of the vocal tract for voice.
During swallowing it is of course important that food does not enter the windpipe. Once food has been chewed in the mouth the bolus is pushed backwards by the tongue into the back of the throat (oropharynx). To prevent the food bolus going into the nose the soft palate rises and the superior constrictor muscle contracts sealing off the nasopharynx. Together with the middle and inferior constrictor muscles it also helps propel the food bolus towards the oesophagus. The vocal folds and false cords close tightly together and the whole larynx rises upwards. The epiglottis tilts backwards forming a lid over the larynx preventing food going into the windpipe and helping direct it into the oesophagus. At the same time the upper oesophageal sphincter relaxes allowing the bolus to move from the pharynx into the oesophagus where a series of contractions propel it downwards into the stomach. Once the food has been swallowed the upper oesophageal sphincter closes off the top of the gullet so that food cannot be regurgitated back into the mouth. If you speak and eat at the same time food can easily go down the wrong way!
Air can be breathed in through the nose or mouth. When passing through the nose the air is filtered from particles such as dust and pollen and also humidified and warmed. It also allows breathing while chewing food. However when large amounts of air are required such as during exercise it is necessary to breath through the mouth. We change between nose and mouth breathing subconsciously at rest or when talking. Mouth breathing tends to dry out the vocal cords a little more but it is sometimes necessary to get enough air in rapidly before singing the next phrase.
Shaping the vocal tract
The voice is produced by the interaction of the sound produced by vibration of the vocal folds with the acoustic resonance of the vocal tract. Shaping the vocal tract by moving the lips, positioning the tonguein the mouth and oropharynx , moving the larynx up and down alters the vowel sounds and allows consonant sounds to be made for speech and singing. Lowering the larynx generally produces a darker sound colour while raising it causes a lighter sound colour. There are named constrictor muscles (superior, middle and inferior constrictor muscles) but there are many other ‘constrictor muscles’ in the neck such as the extrinsic laryngeal muscles which also help in the constriction and laryngeal positioning because of their attachment to the jawbone, base of the skull, sternum and collar bone. The intrinsic laryngeal muscles are the muscles within the larynx which open and close the vocal cords and alter the shape of the vocal folds so that the pitch, loudness and vocal mode can be changed.
The ‘constrictor muscles’ that shape the vocal tract are very useful and also protect the vocal folds if a singer is exposed to great strain. The throat constricts if, for example, we lift something heavy or become emotional or frightened. Constriction of the throat is quite practical when we lift something heavy, because it prevents a strain on the vocal folds, but it is very impractical to constrict uncontrolled around the voice when we sing as the vocal folds must have room to stretch. Thus, we talk about uncontrolled constriction of the throat being the singer’s main enemy, not constriction or the constrictor muscles themselves.
It is not difficult for the vocal folds to stretch or slacken, but it becomes difficult if the movement is obstructed. An obstruction is any uncontrolled constriction that prevents the vocal folds from stretching, thereby making it difficult to reach higher notes. A singer will try even harder to reach the note, often worsening the uncontrolled constriction. Eventually the vocal folds will not stretch at all. The singer may conclude, ‘I have a low voice, I am unable to reach the high notes’ but this is not the case! The reason why the high notes fail is not a lack of vocal ability to reach high notes but uncontrolled constriction around the vocal folds, robbing them of the space required for them to work, which is to stretch in order to reach the high notes. The ‘constrictor muscles’ of the throat contribute to this uncontrolled constriction.
Avoiding uncontrolled constriction
Singing requires physical strength but this can also cause uncontrolled constriction of the throat. We must therefore, by correct technique, trick the constrictor muscles in the throat into not constricting uncontrolledly even when we sing technically difficult and physically demanding material. This is often called keeping an ‘open throat’. To be precise, it is not possible to ‘open’ the throat, it is only possible to avoid constricting it. When the uncontrolled constriction is gone the stretching of the vocal folds is unhindered, the pitch is secure, and wear or fatigue of the vocal folds is avoided. Basically, singing techniques are about avoiding uncontrolled constriction, and this is obtained by using support, amongst other things. With efficient, solid support we can use lots of physical strength without uncontrolled constriction in the throat. A skilled singer knows the feeling of uncontrolled constriction and is able to avoid it in all situations.