Belting is a specific technique of singing by which a singer carries their chest voice above their break or passaggio. Belting is sometimes described as "high chest voice", although if this is done incorrectly can potentially be damaging for the voice. It is often described as a vocal register, although this is also technically incorrect; it is rather a descriptive term for the use of a register. Singers can use belting to convey heightened existential states. Twentieth-century culture has been distinctly affected by the exponent of belting. The Broadway theatre musical radically changed its course and style with this vocalization introduced by Ethel Merman's singing of "I Got Rhythm" in the Gershwins' Girl Crazy in 1930. In 1964, the James Bond filmGoldfinger had an opening credit sequence oversung with the belting of Shirley Bassey, a signature quality of singing to the James Bond films that continued through to the following century.
Mixing vs. Belting
Belting is sometimes confused with mixing. Belting means to carry your chest voice above your break, while mixing means to mix your chest voice with your head voice. They are two different concepts but their subjects overlap. A belt voice can be mixed or not and a mix voice can be belted or not. One is able to belt purely and is able to belt with a head voice, which is also called mixing while one is able to mix their voices below their break and is able to mix above their break, which is also called belting.
Technique
"Chest register" is the lowest register of the singing voice, produced by dominant use of the thyroarytenoid muscle. The term "belt" is the use of a chest voice in the higher part of the voice. The chest voice is a general term for the sound and muscular functions of the speaking voice, singing in the lower range, and the voice used to shout. Each of those functions requires a thicker closure of the vocal folds and the support of the muscles surrounding them. The term "chest voice" is, therefore, a misunderstanding when it describes muscular work in the chest area of the body or a resonance therein. Proper production of the belt voice, according to some vocal methods, involves minimizing tension in the throat and a change of typical placement of the voice sound in the mouth, bringing it forward into the hard palate, although techniques vary by pedagogical style. It is possible to learn classical vocal methods like bel canto and also to be able to belt; in fact, many roles now require it. Vocalists trained in a wide berth of styles describe vastly varying experiences in the learning belt technique. Some claim that it comes naturally, while others struggle to access chest register other than while speaking. The style of music does not seem to be a related factor, other than in a singer's exposure to the material. Belt technique requires muscle coordination not readily used in classically trained singers as the thyroarytenoid muscle is dominant, which may be why some opera singers find learning to belt challenging.
Physiology
There are many explanations as to how the belting voice quality is produced. Under a scope, the vocal folds visibly shorten and thicken, and they undulate along with more of their vertical surface area than in head register when a smaller segment of their edge must undulate to produce sound. One researcher, Jo Estill, has conducted research on the belting voice, and describes the belting voice as an extremely muscular and physical way of singing. When observing the vocal tract and torso of singers, while belting, Estill observed:
Minimal airflow
Maximum muscular engagement of the torso
Engagement of muscles in the head and neck in order to stabilize the larynx)
Belting without proper coordination can lead to constriction of the muscles surrounding the vocal mechanism. Constriction can consequently lead to vocal deterioration. Correct use of the technique and, most importantly, retraction of the ventricular folds while singing is vital to safe belting, as it is, in essence a form of "yell" and thus involves a tremendous increase in the force exerted on the soft structures of the pharynx vs. more common modes of singing. Attempting to belt too loudly, in too high a register and without properly supporting the ventricular folds are the "Three Devils" of the belter; an untrained belter may well consider the short term irritations caused by bad form to be just a "part of the job", when in reality it indicates a flaw in their belting skill that will cause long term serious damage if not changed. While acknowledging the extra risks inherent to belting, many proponents take pains to point out that it is an advanced skill which is no more damaging to the voice than any other type of singing. Indeed, some genres of singing rely on belting to allow the vocalist to "cut through" the electric guitar while playing live. Many in the musical theater industry like to quip, "belting is not bad; bad belting is bad.", As for the physiological and acoustical features of the metallic voice, a master's thesis has drawn the following conclusions:
No significant changes in frequency and amplitude of F1 were observed
Significant increases in amplitudes of F2, F3 and F4 were found
In frequencies for F2, metallic voice perceived as louder was correlated to increase in amplitude of F3 and F4
Vocal tract adjustments like velar lowering, pharyngeal wall narrowing, laryngeal raising, aryepiglottic and lateral laryngeal constriction were frequently found.
