The Bird has become a rubber duck! quacking sound!!!!

[MWS]

Try and identify which wheel is the culprit, then start with the simplest things. Look for anything that might be contacting the tire (plastic flap, etc) and check your tires. I once had a tire that made a "flap-flap" noise...it turned out a plastic label. Also try to free spin the tire and pinpoint from there. I always start with the simplest/dumbest things and work upwards.