Getting a deep, manly voice is just another one of the changes that boys go through as they grow into men.
Voice breaking is part of what happens to boys during puberty.
Everyone is different, but puberty usually begins between the ages of about 12 and 16.
A boy's voice will start to break after his testicles (balls) and penis have gone through a growth spurt.
The reason why male human voices should change at puberty isn't certain.
In other animals, deeper male voices appear to be more attractive to females and better at frightening off predators and other males.
Hormones affect the way the head and voice box grows.
The vocal cords that allow us to speak grow thicker. This means they can't vibrate as quickly to produce higher notes like they did before.
The head grows and changes shape too. The air spaces up inside the nose (sinuses) and inside the mouth and throat get more roomy.
These bigger spaces make deeper sounds coming from the voicebox sound louder.
Meanwhile, the whole voice box tilts to a different angle. This tilting makes the voicebox poke out through the skin of the neck more, giving men their 'adam's apple'.
While these changes are happening, some boys find their voice gets croaky.
Others can find their voice suddenly flipping between low and high.
It can be a bit embarrassing if it happens in public, but this stage usually passes quickly.