Determine the pattern of vibrating waves that can be produced when common items such as fabric and other various textured surfaces (such as non-polished table top, concrete), are gently scratched with a solid object such as a nail or pen cap.
Carefully place a sample of each material on a smooth surface. While holding one edge of the material securely against the surface, drag the nail or pen cap slowly but firmly across the material. Listen to the sound produced as the nail crosses each thread. Repeat using different types of material and other surfaces. Can you identify which material will produce patterns and which would produce non-patterned noise?
One safety feature that many interstate highways now have is the textured strips on lines and edges of the road. These features produce a specific sound when tires pass over them. These are carefully designed to alert drivers to where they are out of the lane or off the road. To produce these warning sounds there are distinctive patterns “recorded” in the surfaces when it is rubbed (or strummed) by a passing tire.
Next time you’re in a car, listen closely to the sounds the traffic makes as it travels along different streets and road surfaces? Different tires and tread patterns will also create different sounds. Some noises are higher pitched and create a high whine while others seem to produce a low moaning sound. Taking into consideration all the different variables of surface type, tread pattern, speed of the vehicle and even the temperature, you really can have a symphony of the highway. (Don’t forget about the percussion section as you encounter bridges, stoplights and lane changes.)