An Internet article by Jenevora Williams states that boys' voices begin to change at around age 12-13, finally settling about 15-18 years old. Ms. Williams urges that boys should be encouraged to keep singing throughout the voice change years. I agree. I believe that singing and wise vocal training can help boys develop steadier, co-ordinated voices, as well as better senses of rhythm and pitch. This gives them a head start with their vocal abilities as adults.
In another Internet article, Christina Clark notes: "There is no vocal exercise that will help to extend or lower a range that isn’t there. However, training an unchanged voice is definitely not a waste of time. By getting the student comfortable with singing in his upper register, this can help to keep a nice, clear head voice when his body does begin to change".
The biggest issue I find with young boys is vocal strain! They try to "MAKE" their voices work, screaming through the hard places. I teach boys with unchanged voices to sing as high as they can without strain, and I take them as low as they can go without sounding "hooty" or dropping the larynx. My awesome little student Ike Hawkersmith landed a professional role as "Amahl" in "Amahl and the Night Visitors" this way. I coached him to sing with a confident, talking style, which helped him even out his tone and intensity. Not only could he sing clear, floating high notes, he could also get the lower notes of his part without loosing volume and tone. Like all my students of all ages, he learned to "Pull" instead of "Push" his words in all parts of his range. This way he kept consistent, lively tone production throughout this range - and he experienced no strain in practice, performance, or recording.
The boys and young men I've worked with after their voices have changed have different issues. They are sometimes afraid of their upper register. I teach them not only to sing in the new-found lower register, but also to vocalize in head voice, Pulling their words in all registers instead of Pushing any note. Though I am careful not to fatigue this young male voice in the passagio, or "land between the voices" range, I DO have them sing comfortable exercises crossing voices. This helps them develop the all important "mixed" voice. Grown men I've taught sometimes didn't even know they HAD head voices! They learn that singing in head voice and falsetto (a lighter head resonance vibrating less of the vocal cords) adds richer resonance to their lower register and lifts the ceiling off their ranges. After they get over the shock, they like it, and some use a bit of new found "falsetto" in their professional careers!
Adolescent girls have their own issues. We'll talk about them next time :)