Lower female voice is indeed extremely sexy. But it would not necessarily make you look older - after all, it is sound, not video .

Scarlett Johansson has the sexiest voice in Hollywood (not just per me but per the makers of the movie "HER") but it does not make her look old. It just helps her look even sexier - much, much sexier - than she would look if she had a shallow top notes voice with the same figure and face.

I guess what I am saying - if you have low notes in your voice, it is fantastic and do gradually build up towards revealing them, but do not expect to look older.