Question

Typically, when a three-year old child produces phonation, the relative pitch will be higher than that of a child who is 8-years old or an adult. Why is this most likely true?

Vocal folds get longer as children grow and therefore the relative pitch will increase with age.  

Vocal folds get longer as children grow and therefore the relative pitch will decrease with age.

Vocal fold tissue hardens with age and vibration slowly becomes more restricted, therefore relative pitch will increase with age.

Older children and adults have longer vocal tracts and this alone can account for relative changes in pitch that occur with age.

Answer 1

B) Vocal fold get longer as children grow and therefore the relative pitch will decrease with age.

When vocal cords vibrate sound is produced. The pitch of the sound produced is controlled by how tightly the vocal cord muscles contract as the air from the lungs pushes the vocal cord. When the child is three years old  his larynx is small and his vocal cords are small and thin, that's why his voice or pitch is higher than an 8-year old boy. But as he goes older, the larynx gets bigger and the vocal cords lengthen and thicken, so his voice gets deeper and pitch decrease.