Engineers in Japan have altered sections of more than 10 roads in order to create musical road surfaces. By cutting grooves in the road at various intervals, these so-called "melody roads" combine high and low notes to simulate a tune for motorists driving over them. When cut close together, these ridges produce high notes. Ridges encountered farther apart produce lower notes, almost like driving over the rumble strips that warn that you're headed off the road.
Reviews of the melody roads have been mixed. You can apparently hear best with the windows rolled up, but even then the quality of the "song" can be poor. It also depends on how fast you're driving -- Japan's road songs sound best at 28 mph (45 km/h) and last half a minute.
More about melody roads:
Not sure I'd like a road melody competing with my car's sound system when the radio or tape/CD is playing. Seems novel but driver has no say in the program.