ECOTEC06SS

Okay so im driving and when i hit about 35-40 mph i hear some weird ass noise start and it continues as i accelerate but does not get louder, i cant tell if its coming from me cat converter or more from my tires, idk its hard to tell, but the noise kind of sounds like i have off road tires, iv been wondering if it was a exhuast leak but if it was it would be alot louder, its a sort of light noise but its noticable, does anyone have any idea on what it could be? ill try and get a video up in a bit.......