There are obviously a nuumber of issues that can result in a very similar symptom of this "cow bell" type noise. My e-brake caused it, and I've had pebbles caught in the dust shield, in several cars, that resulted in a very similar noise. If you have an object caught between the shield and brake rotor, you can easily determine that by inspection. Pressing the shield away from the rotor will dislodge the object and you are fixed. If it is the same e-brake issue I had, you will find no foreign object lodged there, and the problem will not go away, but will get worse until it is almost a constant issue.
2011 Space Gray Coupe, DCT, ZCP, StopTech ST-60/ST-40 BBK.