Talked about before on earlier posts and yes harmonic hum is there with my HJC 3/4 and my Shoei 3/4...Not as bad with the open face HJC but more noticeable with my Shoei...Cobra pipes tend to add to the noise, but it is not bothersome to me anymore...Foam earplugs help some, but I have issues wearing plugs for some reason, different size ear canals or something....Anyhow going into the 3rd riding season soon, I will just motor on!!!!....Ride safe