The hands of a singer (hey, or a speaker) make an interesting study for me. Personally, if you were to make me freeze my hands in place, I don't think I could sing- or talk! Years ago, a studio engineer in Memphis told me to stand perfectly still at the mic. This guy was NOT a singer and therefore trying to explain how stiffness affects the voice was falling on deaf ears. I did as he asked, and sure enough my tone was dead, my performance numb, my vocal range limited. Thank goodness I knew to ignore that advice from that time on.
Consider the traditional hands-clasped-in front-position used by classical singers. Now visualize the "smooth-move" hands of a hip hop artists such as Usher. Next think about the expressive hands of a pop vocal diva such as Celine Dion. Now the subtle hand-speak of an R&B icon like Aretha Franklin or the sultry hand moving of jazz singer Jane Monheit. Read the message given by the hands of gospel singer Cece Wynin; remember Christina Agulera singing "This Is A Man's World" on the Grammys a few years ago. Think about the conversational hand-talk in performances by Garth Brooks and Faith Hill. Lastly, remember the incredible performances of Michael Jackson in the recent show they pieced together for "This Is It".
In different ways, they are all doing the same thing. All these vocalists are using their hands to help with their breath control and to keep their throats open... whether they know it or not!