How Does the Singing Voice Function?

​How Does the Singing Voice Function?
Written for Walton Voices by Zoran Milosevic
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01932 246 635

In my previous article (here) I discussed the options for improving an amateur singer’s voice. In the few next articles, I will propose a series of exercises that will help in achieving this, but before we go deeper into the singing technique, I would first like to discuss how the vocal mechanism actually works.

All sounds that we hear are produced by oscillating pressure waves of the surrounding air. Therefore, to make a sound, we need (1) a vibrator - something that oscillates (the “source”), (2) a motor – the energy input that moves the source and causes it to vibrate, and (3) a resonator - something that converts those oscillations into an audible air wave. Examples of motors are the drummer’s hand, the breath energy in singing or blowing a woodwind instrument, the guitarist’s finger action, etc. Musial instruments’ oscillators are usually either the strings (violin, guitar, harp) or reeds/mouthpieces (clarinet, trumpet). For human voice it is the vocal folds inside the larynx that oscillate, and it is the vocal tract (the throat, the mouth) that acts as the resonator. Without the resonator the raw source sound would be little more than a quack. It is the resonator upon which depends the beauty of the musical sound, and so is true for the singing voice. The vocal tract is a Stradivarius hidden inside an elite singer’s body.

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​A music line consists of series of notes of varied pitches. There are two ways of producing a specific pitch in music:

• The string instruments (guitar, violin, piano) produce sound and pitch by vibrating strings of different or changeable lengths and therefore different speeds (frequencies), and then using a solid, UNCHANGING acoustic chamber, to amplify those vibrations.
• Woodwinds, on the other hand, produce sound and pitch differently: they have a constant vibration speed (frequency) of the read, and this vibration resonates in the instrument’s chamber. As a larger chamber vibrates more slowly than a smaller chamber, so by unplugging the holes the player reduces the size of the chamber, which makes the notes sound higher.

The voice should work as the string instruments work, but not entirely: because in addition to changing the length/thickness of the vocal fold, singers can also change the shape of the resonator (i.e. the vocal tract).

In order to produce a higher pitch, singers have three basic mechanisms at their disposal, all producing slightly different voice qualities. The mechanisms are:

1. Tightening the vocal fold muscle – most men apply this technique when trying to raise the pitch of their speaking voices. This is the basic mechanism of a singer’s chest voice.
2. Stretching the vocal folds by tilting the thyroid cartilage (the Adam’s apple) forward – this is how most women raise the pitch of their speaking voices. Most men need to learn the technique. It is the basic mechanism of the tilted, or head voice.
3. Raising the larynx to shorten the resonator – untrained singers do this instinctively, and certainly upon reaching the upper limit of heir speaking voices. This technique is not part of classical singing but with proper crafting it is extensively used in musical theatre and popular music (“belting”).

Raising the larynx is easy for us. We use the muscles that move the larynx up and down very often: when we swallow, they pull the larynx up, then down. When we yawn, they pull it down. On the other hand, the muscles that control the vocal folds are harder to consciously manipulate. Therefor many untrained singers will attempt to produce higher pitched notes in a way that feels more familiar to them, i.e. by raising the larynx. You can do a lot of beautiful singing with a conscious and controlled raising of the larynx, but not with the emergency and panicky tightening of the throat as you approach the upper limit of your range. Trained singers however do not allow the larynx to raise, unless for stylistic purpose (for example in the so called voce finta).
In order to prevent the larynx from raising when singing, singers need to re-train the brain so that it allows the larynx to remain stable at the tone onset. Namely, the main purpose of the vocal folds is to close when swallowing, thus preventing accidental choking by inhaling food or liquid. There are two additional mechanisms for more anti-choke safety (the larynx goes up to close the trachea, and the epiglottis flap closes for the same purpose). After repeating the swallowing routine millions of times “close the folds, raise the larynx”, this becomes automatic. Hence, as soon as the vocal folds are adducted for singing (as opposed to breathing when they are abducted), the brain automatically raises the larynx, in its reflex action, thinking that you may be about to swallow something. Appropriate training is needed to prevent this action and stabilise the larynx at the tone onset.
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All three pitch-changing mechanisms mentioned above are used in classical singing – there is a place and the appropriate use for each of them, as I will cover in subsequent articles.

Types of Singing Voices 
In singing we can produce three distinct voice types (voice qualities). They all sound slightly different, and which one will the singer will use depends on the pitch range, the character of the song and the artist’s esthetical intention. In vocal teaching literature they are given various names, but I will use the denominations proposed by Prof. Ross Campbell of RAM in his excellent book “Singing, an Extensive Handbook for All Singers and Their Teachers”; they are:

• Speaking voice – vocal apparatus positioned as if speaking, with no thyroid tilt (also known in pedagogy as the chest voice, modal voice, open voice, TA dominant voice etc.)
• Tilted voices (a.k.a. head voice, CT dominant voice), of which there are two:
  1. Cry-tilt voice – tilted thyroid cartilage, larynx in neutral position or slightly elevated
  2. Sob-tilt voice – tilted thyroid cartilage, larynx lower than neutral position

When singing in the lower registers, most men use their speaking voices (the chest voice), in which increasing the pitch is simple – by tightening the vocal fold muscle, as men usually do. However, on reaching the upper pitch limit of the chest voice (at the “lower passaggio”, see Table) untrained singers instinctively raise the larynx (shortening he resonator) in order to sing higher, and attempt to further tighten the vocal fold in an unhealthy (yelling) manner. That is the only mechanism known to an untrained singer, as discussed above. This “technique” will not take you far in extending the vocal range, it will produce an unpleasant sound, it is unhealthy, and it makes intonation and pitch accuracy difficult (because you use simultaneously two mechanisms for pitch control).

​As mentioned above, trained singers do not move the larynx as they ascend in pitch, unless they deliberately chose to do so for stylistic purposes. On crossing the first passaggio, trained singers start to tilt the larynx, and gradually introduce the head voice. Above the first passaggio they sing in the so called “mixed voice” (a mix of the speaking and the tilted voices, the contribution of the tilted increasing as the pitch increases). The elite singers almost exclusively stay with a low larynx (sob-tilt) and raise larynx only for effect, while average and amateur singers may find it easier not to the use the sob-tilt voice at all.
In subsequent articles, I will describe the techniques that produce various voice qualities in more detail.