The term "belt" in music means the use of "chest" voice in the higher part of the voice, rather than using the "head voice," etc. However, the proper production of the "belt voice" involves minimizing tension in the throat and modulation of vowels and change of typical placement of the voice sound in the mouth. In a higher range all vowels are modulated to one of two vowels: "eh" as in "ape" or "ah" (bright vowel) as in "ChicAgo." Depending on the range of the singer, the vowels will be more or less modulated. Hence, in a male voice, a belted A-flat might not have the same amount of modulation as a belted B-flat. In males, belted voices often sound similar to classical, or "legit" singing techniques, such as Bel Canto or Speech Level Singing. In females, classical methods are not similar as the higher range of a singer in classical singing in females is done in head and falsetto voices.
In addition to the modulation of vowels, the belt voice sound is produced by properly placing the sound in the mouth. The soft palate is raised and the vowels brightened toward the front of the mouth. The jaw is open (but not fully open) so that a few teeth are typically showing on the top and bottom of the mouth. There are various techniques and vocalises to accomplish this sound. The result is a kind of "soft yell."
It is possible to learn classical vocal methods like Bel Canto and to also be able to belt, in fact many musical roles now require it. The belt sound is easier for some than others, but the sound is possible for classical singers, too. It requires muscle coordinations not readily used in a classically trained singer or female student of Speech Level Singing, however, as these muscles are generally used only during high chest voice production or when making straining noises which singers trained in these styles are told not to do.
Is it safe?
Some singing methods and teachers of them and related methods regard belting as damaging to long term vocal health, they may teach an alternative using the Head register which may or may not be as strong sounding depending on how much practice is done. The subject is a matter of heated controversy among singers, singing teachers and methodologies.
Despite the sound being somewhat of a "soft yell," if produced properly it can be healthy. It does not require straining and it is not damaging to the voice. Though the larynx is slightly higher than in classical technique, the vocal cords are not harmed.
However, it is thought by some that "belting" will produce vocal nodes. Nodes can show up when the vocal cords are unhealthily slapped together in a "glottal attack." Belt pulls the vocal cords very close together, but air can still pass through safely without causing a "glottal attack."
Others believe that a healthy belt technique can be practiced, and in fact belt technique can be used as therapy for vocal cords.
Physiology of belting
There are many explanations as to how the belting voice quality is produced. When approaching the matter from the Bel Canto point of view, one might say that the "chest voice" is applied to the higher registers. The chest voice is merely a description of a sound quality though and does not describe a physical activity. For many years, voice practitioners were limited to judging a voice based on what they heard. Now, thanks to many years of research, more is known about the anatomy and the physical process of singing than ever before. One of the great vocal researchers of these times is Jo Estill. She has conducted extensive research on the belting quality. Jo describes the belt as an extremely muscular and physical way of singing. When observing the vocal tract and torso of singers, while belting, the following is observed:
- Minimal airflow (70% closure)
- Maximum torso anchoring (activating the large muscles in the back to control airflow)
- Head anchoring (activating the neck and head muscles for stabelizing the larynx)
- Tilting of the cricoid (We know that the space between the thyroid and the crycoid widens. It seems that the cricoid is tilting downwards, although there might be thyroid activity as well).
- Highest position of the larynx
- Maximum muscular effort of the external muscles. When produced healthily, there is no tension in the vocal folds themselves.
- Constriction of the aryepiglottic sphincter (the "twanger")