Some sound making devices have been implemented into the construction of roads. These give of a rumbling noise warning drivers that they are headed off the roadway or towards oncomming traffic.

One such device is the rumble strip.  Rumble strips are small indentations or narrow raised strips on the highway or shoulder. They vibrate the steering wheel and make a noise inside the vehicle to get the attention of the driver. They alert the driver to a sudden change ahead, such as an intersection after a long stretch of road.  Or wake the driver who may have dozed off and run onto the shoulder of the road. When you hear the rattle sound made by a rumble strip, don't mistake this for a mechanical problem with your car.  Look for warning signs or hazards ahead.

Keep your ear to the road!