Why does my 2006 Jeep make a noise while stepping on the gas pedal?

Everytime you step on the gas pedal on my Jeep it makes a buzzing sound, as you go faster it gets louder it gets pretty annoying. Its been a year since i've had my jeep and i finally got tired of the noise and wanna know what it might be? Does anyone know? Has this happened to you? As soon as you stop accelerating it stops though. HELP!