Whistling as wheels rotate

[shotta287]

Past week or so there's this annoying whistling from my car (2009 Audi A3) in tandem with wheel rotation as I drive. Can't pinpont which wheel and I'll take it to a garage on the weekend get it on ramps and spin each wheel but what could it be? Rear pads replaced in January and front discs and pads replaced last month. I'm hoping its not a wheel bearing or sticking caliper.