Generally the voice of women is sweeter than men. Even boys have feminine voice till the age of eleven or twelve years. But later it starts becoming deeper. Voice of girls, however, does not change much with age.
Normally the age of eleven to thirteen years is known as the period of puberty. During this period some of our glands produce sex hormones. These hormones bring many changes in the bodies of boys and girls. In boys they are responsible for the growth and appearance of the hair under arms, auxiliary hair, pubic hair and facial hair. The voice of boys starts becoming deeper. Their bodies produce a hormone called ‘testosterone’ which is mainly responsible for changing the length and thickness of the vocal cords. This also affects the larynx. As a result a man’s larynx becomes larger than that of a woman. Man’s vocal cords are also longer than those of woman. Due to this the frequency or pitch of a man becomes lower than a woman’s and hence the male voice becomes deeper than that of a female.
Though this hormone is not produced in the girls, yet a slight change takes place in their voice also. This change occurs mainly due to the further growth of their throat, mouth, nose and upper jaw.