So far on our journey we have grasped the importance of the support structure for the voice, and looked at breathing. This next step of the journey initiates "sound" for the voice. The breath stream rises up the trachea from the lungs and runs into a constriction. This is the "voice box" where the vocal chords - now called folds - are set in motion by the breath stream and they create a buzz. If the vocal folds could operate without any of the resonating areas above it (i.e. without your head!), the sound made by the vibrating folds would be similar to a "raspberry" made with the lips, or perhaps a duck call.
Remember that Vibration = Sound. The vocal folds "chop" the air stream up into a series of rapid "puffs". How rapid? If you were to sing an A above middle C (A440) -- not very high for a woman, your vocal folds would vibrate at 440 cycles per second (also called Hertz, or Hz). It is important to realize that it is the puffs of air that create the sound, not the impact of the folds coming together. It is more similar to waving your hand in front of your ear, which creates waves of air pressure or turbulence, than clapping your hands together.
It is important to remember that speech is not only made of phonated sound. In fact there are many sound sources in speech.
- the vibrating vocal folds, (a pure, spoken "ah", for instance)
- turbulence caused by constriction, ("shush"ing someone)
- blocked air flow (glottal stops & unreleased plosive consonants [ k, p, t ]).
In this latter case, our minds interpret the silence, or absence of sound, as a sound unit.
Phonation occurs in the larynx ( pronounced La - rinks, not Lar - nicks). Understanding its complex anatomy and physiology is quite an undertaking. Part of the problem is that the information you glean may be hard to use as a voice user. The muscles of the larynx work "involuntarily", meaning that we have little control over them directly. Control of the laryngeal muscles is done through a biofeed back process involving sensing and monitoring the vibration of the vocal folds through the sound and feeling it creates. Learning to make adjustments to those actions is a complex and slow process, one that takes a lifetime to master. Any knowledge about the structures that create those sounds and feelings can only help you to appreciate and analyse what is being felt and heard.
Phonation - Laryngeal features:
- Anatomy part one - overview and the cartilages
- Anatomy part two - mucosa and muscles
- Physiology - how it works
More on Phonation
Video and audio media of the voice box
Voicedoctor.net presents a wide array of imagery, audio and video of the larynx and of normal and pathological voices. Highly recommended. posted April 15, 2004.
of Laryngeal Pathology
The Centre for Voice Disorders at Wake Forest University presents a (very slow to download) site with many pictures of diseased vocal folds - including adhesions, removal of a cyst, granulomas... Some pretty gruesome sites.