Typical Age Range
This stage begins when the adolescent growth spurt slows to childhood rates or below and ends when growth in height ceases. On average, it typically begins around age 15, but can start as early as 9 or as late as 19. It typically lasts about two years.
By ethnicity:
- Non-Hispanic White: Earliest – 11.5, Average – 15, Latest – 19
- Hispanic: Earliest – 11, Average – 15, Latest – 19
- Non-Hispanic Black: Earliest – 9.5, Average – 15, Latest – 18.5
Characteristics and Changes During Stage 4:
Growth
Growth begins to slow, though an additional inch to three inches will be gained. The slowing of the growth rate is the primary marker for the start of stage 4.
Genitals
The scrotum distinctly hangs and takes on a darker color. The testes are between 1 1/2 to 1 3/4 inches (4.1 to 4.5 cm) long, measured along the long axis, or measured in volume, they are 12 to 20 ml.
The penis continues to grow, but mostly in width. The glans at the end of the penis widens and develops a distinct corona. If ejaculation of semen hasn’t happened earlier, it will begin in this stage.
Hair
Pubic hair is pigmented and curly, spreading across the groin. A strip of hair forms from the groin up to the navel. Hair under the arms becomes denser.
Facial hair develops on the upper lip, chin, and near the ears. Continues to spread across the face as this stage continues.
Voice
The voice continues to crack at times and deepen.
Body
Acne breaks out on the face and body.
If breasts stand out, they begin to disappear. Nipples stick out and become both harder and more sensitive to touch.
Muscles begin to develop.
Shoulders begin to widen, giving a typical male physique. The trunk region grows, but at a slower rate than the legs in stage 3.
Attitude
Still tends toward extremes in mood, although this tendency has somewhat settled down.