That's good advice about the choir, Fred.

Despite how pop stars and opera stars do it (the same way all the time), people can sing differently at different times. A woman can produce an angry, bluesy bellow or a delicate lullaby. She can sound young, clear and sweet, or she can sound husky and weak.

'Cause a voice isn't something you HAVE. Singing is something you DO.

A competent teacher will know this. The point of voice lessons is to learn how to do these things and to do them without harming your voice.