© Dreamstime Agency | Dreamstime Stock Photos A Duke University study has found that men with deeper voices not only are more successful, but also make significantly more money. How much more money? $187,000 per year more than men with higher-pitched voices. How much deeper does the voice need to be to make a difference? Apparently 22.1 hertz which is approximately 1/6 the difference between the pitch of James Earl Jones (low-pitch) and Mike Tyson (high-pitch). Other research (see b…