From early childhood up to puberty the pitch range of children increases. There is very little difference in size of the vocal folds between boys and girls. During puberty, boys lose the ability to control the pitch of sounds. The size of the male vocal folds increases considerably with a resultant reduction in the pitch of the speaking or singing voice of about an octave. The increase in the female vocal folds is about 30 percent.
Boys then have to relearn how to control their vocal folds.
This often takes as long as a year. As both men and women become older, their pitch range begins to decrease, mainly due to loss of elasticity of the muscles of the cartilage in the larynx. In addition the voice often ac quires pronounced tremolo. Figure 7.19 Sectional view of the human head show ing the vocal folds and resonant cavities. They each function to both increase the overall loudness of the voice and affect the quality of the tones produced by selectively intensifying certain frequencies.