Having been nearly deafened by the high pitched whine produced by driving down the grooved interstate in Iowa, I’m wondering if anyone has ever intentionally cut road ridges in such a way as to produce musical sounds or speech when a car is driven over them ?
Damn. That’s a cool question.
I’d figure, though, that while it would work, speed, road wear, tire wear, and tread pattern, as well as suspension calibration, would all alter the sound or voice.
But hell, I’d like to see it. Lines that say “Slower vehicles please keep right” every mile. Music might be too soothing, though. Could put people to sleep. I could seriously go for a subliminable “Give Tim road head” but with my luck, I’d drive over it with a guy in the passenger’s seat. :eek:
Neat idea. However it’ll be difficult to produce a very high frequency - the tyre’s contact patch is about two inches long, so any bump or groove smaller than that will have little effect. At 60 mph the sampling frequency would be about 500Hz, which means it can only reproduce 250Hz sound. Enough to reproduce a simple tune, but probably too low to reproduce voice. In addition, the suspension introduces a frequency-depenent attenuation of the sound, so the sound quality will be low.
While driving to work years ago, on a road that was grooved to be resurfaced, I wondered the same thing. There’d have to be a set speed limit and the driver must go at that constant speed. I wonder if there is a tire size/wheel base effect?
I say we put in for a grant and see what we can do!!
Road hum sounds closer to 600 Hz at 60 mph than it does to 250, so something is wrong with the 1056"/sec X 2" contact calculation. Perhaps a tires tread decreases the effective size of the contact ? I suspect it is the “edges” of the tire grooves and not the entire contact zone that produces the sound.
I tried sampling speech at 500 Hz and it’s unintelligible, but somewhere between there and 1000 Hz it becomes perfectly understandable. It may be that only speeders could hear the messages, but it seems that the only way to find out is to try it.