This week in Lancaster, California, city officials decided to pave over a stretch of road after complaints from neighbors. The road was recently modified as part of a publicity stunt by Honda so it plays the Lone Ranger song (William Tell Overture) when driven over, leading to increased traffic on the road. I have a few questions risen from this:
-Looking at footage of the road on YouTube and some local TV station sites, the road certainly sounds like the William Tell Overture- however, it sounds like a horribly off-key version. Some news outlets are claiming it sounds “in perfect pitch” when driving a Honda Accord. Would the type of car being driven really affect the pitch?
-How is such a thing actually done- that is, how is the road paved so that it “sings?” Could any song theoretically be done, or would it just come out sounding off-key as this one does?
Exactly. Assuming a constant speed of travel, only the spacing of the ruts in the road could affect the pitch intervals between notes. You’d have to drive at a specific speed to get the tempo right, but even if you’re too slow/fast, the music should sound in tune with itself if it’s done right.
ETA: The kind of car, and especially the kind of tire, could affect how audible the road noise would be inside the vehicle, but I still don’t think it would make it sound in tune or off-key.
ETA x 2: What am I saying? The speed of travel will only affect the speed of events (rhythm), not the pitch. I’m assuming the size of the ruts in the road are responsible for pitch change.
I’m guessing it works by spacing ridges different distances apart, and when you ride over it, those that are closer together will give the impression of higher pitched sounds. Years ago, I found a little plastic strip about 3 feet long that had ridges placed and spaced at carefully designed places. When you ran your thumbnail from one end of the strip to the other, you heard, very distinctly, “Happy Birthday” in a sort of singsong voice. With one end tied in a knot and the rest hanging from a Kentucky Fried Chicken bucket, it was amplified and sounded very much like a person speaking. I used it in my classes for a long time before it finally degraded. Somewhat like the sound you get when you run your thumb along curling ribbon. Can’t figure out the connection to a specific type of car, off hand, however.
I saw this on the news and was more curious about the neighbors complaining about the noise. The clips I saw showed that there were no homes along that road, it seemed to be mostly empty fields, so how close are the nearest neighbors and can they really hear it?
Also, would the person in the car hear it the same as someone standing alongside the road?
It should be slightly different for people depending on their location because of the Doppler effect. Those in front of the car would probably hear it all slightly higher and possibly slightly distorted. Those in back would hear it all slightly lower, and also possibly slightly distorted. The distortion, I believe - without thinking it through sufficiently, I fear - would be due to the change in the intervals between tones; compressed in front and expanded in back. Much as the folks on a train hear the whistle differently from the way people OFF the train hear it. I gotta go check out this video. xo, C.
Here’s the other thing to consider (I don’t know anything about this particular stunt). The front tires and the rear tires are going over the same set of ruts, but of course the rear tires lag behind by a short time, maybe around 0.2 seconds at 45 MPH. But in music that’s enough to cause an echo effect. I don’t know but there could also be a phase effect if the front and the back are over the same patch at the same time. That is, if the front tire is in a trough when the rear tire is over a peak, then there will be some cancelling effect. This could be calculated to be complementary to the wheelbase of the car if they wanted it to sound best with an Accord (or a car with the same wheelbase).
Figaro, You were originally correct to think that the speed changes the pitch, not just the tempo. I need to look at the video but I assume this is like the rumble strips they use as you approach a toll booth. A musical pitch is just a series of “bumps” at a particularly frequency, and those “bumps” can be the air moving back and forth from a violin string, or a tire going over bumps in a road. The pitch is directly related to the frequency. So you go over the same bumps faster, it’s a higher pitch. If your speed is constant but the bumps get closer together, it’s also a higher pitch.
If you drive faster, then you are basically transposing the song. If you go about 26% faster, you are transposing up about a major third
I don’t think anyone standing along the road would hear it at all, they wouldn’t be able to anyway, it plays for like 30 seconds anyway, so you’re talking about a half mile distance from start to stop. I think the complaints were due to the increased traffic in the area caused by everyone wanting to try it.
But my question is, how the hell does Honda get the right to alter roads?