I agree that it’s not Jewish. Granted.
You people have no idea what self-esteem is about. If someone has a better voice than you… that’s not an issue of self-esteem. Most people are better than you in some way or another. Self-esteem is when you don’t feel good about yourself for any reason. If a person has a bad voice (like me) but has other good qualities, there is no reason not to have a healthy self image. Good luck to all you people that think that your self image depends on other people liking your voice!