Popsicle Harmonica -The Science of Sound (Vibrations)

Scientific Concepts :-

What is Sound?

A popsicle (craft stick) harmonica is a groovy way to demonstrate the science of sound because all sounds are produced by a certain kind of motion. As you stretch a rubber band and then pluck it, the rubber band moves back and forth so rapidly that its motion appears blurred. The sound you hear comes from its motion. This very fast, back-and-forth motion is called a vibration. Vibrations are the source of all sounds.

Picture a stone thrown into a still body of water. The rings of waves expand indefinitely. The same is true with sound and what happens with a popsicle harmonica. Irregular repeating sound waves create noise, while regular repeating waves produce musical notes.

The human ear detects a sound wave. Also, sound waves have special characteristics that make them unique.

Not all vibrations create sounds that humans can hear. Human ears sense vibrations within speeds between 20 – 20,000 vibrations per second. If a vibration is too fast or too slow, it will not be heard as “sound” by humans. One vibration too fast for human hearing is the ultrasonic signal emitted by bats for echo-locating. Vibrations that are too slow for human hearing include ocean waves and earthquakes. We detect these vibrations by seeing and feeling them, but we do not hear them.