Review Question - QID 214383

An 11-year-old boy is brought in to his pediatrician by his mother for a sports physical. The boy has had no past medical history except for seasonal allergies. On exam, his height is 4’8” and weight is 75 pounds. His temperature is 98.2°F (36.8°C), blood pressure is 108/80 mmHg, pulse is 64/min, and respirations are 12/min. His mucous membranes are moist and cranial nerve exam is normal. His lungs are clear to auscultation bilaterally with no increased work of breathing. Heart sounds are normal. On genitourinary exam, he has sparse pubic hair starting to develop at the base of the penis. Extremities are warm and well-perfused, and there are no gross deformities. Which of the following changes can also be expected at this stage of development?