User blog comment:763492/Hatsune Miku on Hollywood's Walk of Fame/@comment-24.17.74.245-20141021021549/@comment-53539-20141022072739

I think its justified as once a singer leaves their teens, their "youthful" voice suddenly looses demand.

The high pitched vocals tend to be limited these days to only pop teen idols.

Most of the young singers are not actually that good at singing as well, as hard as it is to imagine, a lot of them get popular only because of the way their voices are either manipulated or because there is something in their vocal that they can use to prove a pont. So high pitched tones don't tend to be carried into adulthood. When your an adult things go from "pop idol" to "professional singer" and most young singers can't always maintain a professional singer status.

Imagine this... You've already lost your youthfulness that made you famous, and if they can't be a professional then the fiz out of existence. If they do go the professional route, then the music industry in the west tends to favor only a few limited vocal types. So your voice is then directed to be what producers can work with and deeper tones tend to last because they have the better ranges. Even if its not the producers, even a woman's voice will become more mature over time, so you have time against you. If a singer manages to last long enough to survive, they will eventually end up with the familair mature tone that westerners of all ages overall favour.

There ARE exceptions to the rule, but culturally the western music industry is set up so that you either have the youthful bounce that disappears within 5 years, or you hang in there for a few decades and become just like everyone else. I know people dig into Justin B and 1 Direction, but I wouldn't want their lives. Even 1 direction had it confirmed that if they ever stop too long, they will loose their place in the music industry so they have to keep doing what their doing now their famous or loose everything.

So yeah, there are high pitched vocals that make it, but the number of mature vocals people rely on tend to notice in comparison. :-/