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How does the voice work?...
Voice and speech are the consequence of a complex interplay between physical structure, conditioning
and emotional stimuli. We can simplify these into five subsystems.
- The Brain - which provides Motivation, Language and Regulation,
- The Sensory Nervous System - which distributes the Brain's control instructions and collects feedback for the Brain,
- The Respiratory System - which provides Activation,
- The Larynx or voice box - which provides the Vibration and
- The Upper Vocal Tract - which provides Resonance and Articulation.
In speech, the brain uses the vocal mechanism in a series of conditioned responses to
create communication. When the need for a particular response (the motivation) is
established the brain then sends controlled signals to the muscles throughout the
body to coordinate the behaviour of all its parts and create the desired sounds.
To create vibrations, the larynx needs air to flow upwards through the vocal folds
(or vocal cords - situated behind the "Adam's Apple".) The folds open wide to allow
the breath to be drawn down the trachea (windpipe) by an expansion of the lungs - which
elastically expand to fill the space created when the ribcage expands and the diaphragm
pushes down. To create the reverse flow of air, the ribcage releases and the diaphragm
is pushed back up by the abdominal muscles and the pressure in the trachea (sub-glottal
pressure) increases. The folds, at the top of the trachea, are drawn close to each
other by what physicist call the Bernoulli Effect. As air flows past the constriction
caused by the folds it has to speed up. As it speeds up, its pressure drops, drawing
the folds in. The folds close, causing the sub-glottal pressure to rise, and they are
pushed apart again. Nature has designed the folds to enter freely into a series of
rapid vibrations which appear as a wave motion along their length. In a male voice they typically
come together one hundred times every second, in a female voice about two hundred.
In this way a rapid change of pressure is created just above the larynx. This is the
source of sound (a pressure wave) which travels through the Upper Vocal Tract. Here
it can resonate (loosely "echo"). Most musical instruments are designed to resonate
and create a desirable timbre (tone). By the action of resonance, in the vocal tract,
certain frequencies of the sound are enhanced and others suppressed. The vocal tract
is remarkable in that it can modify its shape and create a range of timbres - the
different vowel sounds. The lower jaw, tongue, lips and palate can all move,
controlling the shape of the resonators, and also closing them off creating
articulation in the form of consonants.
The brain provides the control. It sends continually changing impulses to the muscles operating the vocal folds to adjust their tension and alter the frequency at which they vibrate. In this way the pitch is controlled.
The brain also responds to feedback collected by many means. Sensory nerves collect information from sensors throughout the body. The ears report what the sound is like. Stretch detectors in the muscles report on how the breathing muscles are behaving and sensory detectors in the head give a response to the physical feeling of the vibrations within the vocal tract.
One does not need to think about these actions for them to happen. Breathing is an automatic behaviour, which happens from birth. Others are conditioned behaviours, learned during childhood. However, all these can be consciously controlled, and conditioned reflexes can be modified. How they are controlled and allowed to respond is the skill of the owner of the voice - and of course the techniques that can be acquired through voice and speech training.
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The voice
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Want to know more?
There is an excellent article on the science of the voice written by Ingo Titze. Read on the Scientific American website.
Here is a very thorough article explaining all the most important types of vocal problems. Read on the NYEE website.
"A little knowledge goes a long way..."
You do not need to know how the voice works to use it; but knowledge helps if you need to know how to change the way you use your voice.
You can trust in professionals to help you use your voice, but by developing a knowledge of its behaviour you create a structure in which to learn to use it more effectively!
Ask Talking Voice to help you use your voice to its full potential!
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