1. Fundamental Frequency Change
VF length
At modal frequencies, as VF length increases, frequency increases.
Seems to go against what happens with stringed instruments
Reason for difference: the vibrating portion of the VFs decreases as frequency increases.
Modal freq = one of the vocal registers. Used most frequently and has maximum vibration of VFs.
Falsetto = highest register; only vocal ligament vibrating; vocalis muscle is relaxed allowing max. stretch of vocal folds.
VF mass
As mass increases, frequency decreases
What muscle’s contraction would result in increase VF mass (i.e., the cover relaxes and increases in thickness as this muscle contracts)?
VF tension
As tension increases, so does frequency
What muscle contracts to thin and stiffen the medial edges of the VFs, resulting in higher FO?

2. Loudness Change Degree and timing of VF closure
If VF closed time is increased, then there is more time to build up pressure beneath the folds.
Louder sound occurs when subglottic air pressue is adequate enough to blow the tensed VFs apart (overcome the resistance).
Resistance is the important factor for intensity.
The more resistance there is, the more pressure is needed to overcome the resistance. Thus, when the resistance is overcome, the pressure disturbance is greater = louder.
With loud speech, the pressure beneath the vocal folds _______________ (increases/decreases) and airflow across the glottis (VFs) _________________
(increases/decreases)