The human voice consists of sound made by a human being using the vocal folds for talking, singing, laughing, crying, screaming, etc. Human voice is specifically that part of human sound production in which the vocal folds (vocal cords) are the primary noise source. Generally speaking, the voice can be subdivided into three parts; the lungs, the vocal folds, and the articulators. The lung (the pump) must produce adequate airflow to vibrate vocal folds (air is the fuel of the voice). The vocal folds (vocal cords) are the vibrators, neuromuscular units that ‘fine tune’ pitch and tone. The articulators (vocal tract consisting of tongue, palate, cheek, lips, etc.) articulate and filter the sound.
The vocal folds, in combination with the articulators, are capable of producing highly intricate arrays of sound. The tone of voice may be modulated to suggest emotions such as anger, surprise, or happiness. Singers use the human voice as an instrument for creating music.
Men and women have different vocal folds sizes; adult male voices are usually lower-pitched and have larger folds. The male vocal folds (which would be measured vertically in the opposite diagram), are between 17 mm and 25 mm in length. The female vocal folds are between 12.5 mm and 17.5 mm in length.
As seen in the illustration, the folds are located just above the trachea (the windpipe which travels from the lungs). Food and drink do not pass through the cords but instead pass through the esophagus, an unlinked tube. Both tubes are separated by the epiglottis, a "flap" that covers the opening of the trachea while swallowing.
The folds in both sexes are within the larynx. They are attached at the back (side nearest the spinal cord) to the arytenoid cartilages, and at the front (side under the chin) to the thyroid cartilage. They have no outer edge as they blend into the side of the breathing tube (the illustration is out of date and does not show this well) while their inner edges or "margins" are free to vibrate (the hole). They have a three layer construction of an epithelium, vocal ligament, then muscle (vocalis muscle), which can shorten and bulge the folds. They are flat triangular bands and are pearly white in color. Above both sides of the vocal cord is the vestibular fold or false vocal cord, which has a small sac between its two folds (not illustrated).
The difference in vocal folds size between men and women means that they have differently pitched voices. Additionally, genetics also causes variances amongst the same sex, with men and women's singing voices being categorized into types. For example, among men, there are basses, baritones and tenors, and contraltos, mezzo-sopranos and sopranos among women. There are additional categories for operatic voices, see voice type. This is not the only source of difference between male and female voice. Men, generally speaking, have a larger vocal tract, which essentially gives the resultant voice a lower tonal quality. This is mostly independent of the vocal folds themselves.
Singers can also learn to project sound in certain ways so that it resonates better within their vocal tract. This is known as vocal resonation. Another major influence on vocal sound and production is the function of the larynx which people can manipulate in different ways to produce different sounds. These different kinds of laryngeal function are described as different kinds of vocal registers. The primary method for singers to accomplish this is through the use of the Singer's Formant, which has been shown to match particularly well to the most sensitive part of the ear's frequency range.
Vocal registration refers to the system of vocal registers within the human voice. A register in the human voice is a particular series of tones, produced in the same vibratory pattern of the vocal folds, and possessing the same quality. Registers originate in laryngeal function. They occur because the vocal folds are capable of producing several different vibratory patterns. Each of these vibratory patterns appears within a particular range of pitches and produces certain characteristic sounds. The term register can be somewhat confusing at it encompasses several aspects of the human voice. The term register can be used to refer to any of the following:
Within speech pathology the term vocal register has three constituent elements: a certain vibratory pattern of the vocal folds, a certain series of pitches, and a certain type of sound. Speech pathologists identify four vocal registers based on the physiology of laryngeal function: the vocal fry register, the modal register, the falsetto register, and the whistle register. This view is also adopted by many vocal pedagogists.
There are many disorders which affect the human voice; these include speech impediments, and growths and lesions on the vocal folds. Talking improperly for long periods of time causes vocal loading, which is stress inflicted on the speech organs. When vocal injury is done, often a ENT specialist may be able to help, but the best treatment is the prevention of injuries through good vocal production. Voice therapy is generally delivered by a Speech-language pathologist.
Hoarseness or breathiness that lasts for more than two weeks is a common symptom of an underlying voice disorder and should be investigated medically.