Phonation*

• Flow of air • Adduction of vocal folds sufficient to build up required subglottal pressure • Tension to produce stiffness The vocal folds will then vibration (according to the Aerodynamic-Myoelastic theory.

• At the onset of phonation VF’s are adducted. • As they close the flow of air produced by expiration is interrupted as it can longer escape through the glottis. • Caused and increased in pressure, beneath the closed glottis. • As expiration continues against a closed glottis, subglottal pressure continues to rise, until the VF’s are forced open a little bit. • This causes a small amount of air to be released through the narrow slit. Meaning subglottal pressure falls. • Muscular forces adducting the VF’s now exceed the force produced by the subglottal pressure, and the VF’s begin to close. Aided by Bernoulli Effect.

• Frequency = determines pitch, • Intensity = determine loudness, • Quality = determines individual characteristics of the voice.

Perceived pitch is the perceptual correlate of frequency (number of vibrations/second). The pitch raises as the frequency of vibrations increases. Longer length of vocal folds = lower pitch. Pitch is lower in males < females < children.

• Length = INCREASE = PITCH DECREASE Decrease = pitch increase • Thickness = INCREASE = PITCH INCREASE Decrease = pitch decrease • Tension = INCREASE = PITCH DECREASE Decrease = pitch increase

They are muscle-producing changes in length and thickness. Acts to shorten the VF’s. Involved in fine-tuning.

Vocalis is another muscle involved in changing the length and thickness. Acts to shorten and thicken the VF’s.

• Raising voice if working in a loud environment. This causes a strong adduction causing trauma to vocal folds.

Fluid retention and oedema in whole body. Fluid build up in vocal folds meaning pitch lowers.