[Quietcars] What should Ford's new Focus EV sound like?, Autoblog Green, June 23, 2011

[Ken Stewart]

Mike, it has been many many years since I was under a car or even changed a tire, but I'll try to describe my notion in rough terms;
A small flexible piece of metal would be mounted under the vehicle just in from each wheel positioned so that four small extensions from the wheel rim will strike it with each wheel rotation.  So as the wheels roll faster, the clacking sound becomes more frequent and less noticeable.  A more artistic approach would be to hang down a wind chime to be struck with each rotation!  With a vehicle with those old fashioned hub caps, all that is needed is a loose ball bearing in each hub cap that will behave like it is bouncing around on a roulette wheel.  Admittedly this approach is flawed but it avoids any dependence on high-tech electronics.  With your automotive knowledge, you are invited to improve on my notion.