Want to listen to a poor quality, out-of-tune rendition of a famous melody when driving your car? No need for an expensive car stereo, a singing road can do this using wheel vibrations!
If you drift off the side of a road and hit a rumble strip, you’ll get a distinctive sound intended to alert you and prevent an accident. The pitch of the sound you get depends on the spacing between the bumps or ridges. So if you make lots of ridges like a rumble strip and vary the spacing between the ridges correctly, then different musical notes can be made. Close together ridges (say 6mm apart) give high notes, and far apart ridges (say 12mm apart) give low notes. Make the right pattern of ridges then as a car drives over them, a tune is played. Mind you, in most cases the sound quality is pretty poor, and if the car is at the wrong speed it sounds even worse. Rather amusingly, when Honda tried to create such a road for an advert, they got the spacing wrong and so their version of the William Tell Overture was very out of tune(read this great account).
Videos of musical roads in USA, South Korea, Japan and Denmark
The Japanese have the most melody roads: twelve listed here. Suggested optimum driving speed is 28mph (45km/h). Those shown on the map are:
- Hokkaido: drive west
- Route 370, Wakayama prefecture, plays Miagetegoran Yorunohoshiwo
- Numata-shi, Gunma prefecture, plays “Natsuno Omoide (Summer Memories)”
In City of Lancaster, USA, the road is found along the westbound stretch of Avenue G between 30th and 40th Streets West (it was moved from its original site following concerns about noise disturbing nearby houses). Unfortunately, it’s rather out of tune!
The road in Anyang, Gyeonggi, South Korea is meant to play Mary Had a Little Lamb when driving at 100 Km/h and was designed to help motorists stay alert. However, the videos I have heard all sound pretty terrible and the tune is unrecognizable.
An early singing road was the Asphaltophone in Gylling, Denmark. I’m still trying to find out if it still exists. It used raised pavement markers and was constructed in 1995 by artists Steen Krarup Jensen and Jakob Freud-Magnus. It has been suggested that both Dunlop and Disney played around with the idea of wheel vibration making sounds in the 1950s (more info).