Question:
Do you know when my voice will stabilize and always sound deep, rather than sounding like a kid sometimes? This has been happening since I was 14 and a half, or maybe less, and now I’m 15 and a half.
I still seem youthful to me, but just with a mustache.
Answer:
It takes approximately 2 to 3 years for your voice to transition from your childhood pitch to an adult pitch. Then, it takes several more years for it to stabilize at the new pitch and a few more years to develop the richness of tone associated with an adult voice. You’ll have to be patient.

People gauge another person’s age by many factors. There are the obvious factors of size, proportions, voice pitch, and body hair. However, there are also subtle clues that people notice without even realizing it. For example, the texture of a person’s skin changes as they age, including the appearance of wrinkles near the corners of the eyes, the squareness of the chin, and the way a person moves and sits. Children are much more flexible than adults, and this difference shows up in the way they move and rest.