Just because you can't hear them doesn't mean they don't work, I was cruising up towards Lake Tahoe at dusk and on a long sweeper when one started to come out of the treeline along the road, he stopped dead still and then turned and darted back into the trees. No other cars or traffic except me, so I am sold on them, I have ordered 2 red ones to match the bike and they will go on the front forks somewhere. I would resort to Voodoo if I thought it would help, the darn Deer out here are HUGE.