Wednesday, July 23, 2014

A Simple Oscilloscope

By humming, singing, or talking one can create a variety of cool laser light patterns. This device will allow one to see sound as vibrations or pressure waves. It is called ‘’Vocal Visualizer or Simple Sound Oscilloscope’’ and is one of my first projects at the Exploratorium Summer Institute Teacher Training Program.
I will share how to make this simple device and what is the science behind the working of the device.
We have to cut the pipes into different sizes and arrange it as shown in the picture. Arrange the elbow and “T’’ joints and insert according to the image. Attach the vibration chamber which is made out of drain pipe, balloon and small mirror. Insert the laser into the central single pipe as shown.  Carefully point the laser at the mirror attached to the membrane.
Aim the device on the wall, screen, floor or other reflective surface. Hold the device close to the mouth and hum, sing or just make some weird noises.   
As we make noise, changing the pitch (frequency) and volume (amplitude) we will see a different kind of patterns created on the wall.
What is going on?
When we make sounds, we cause air molecules to vibrate. These vibrating molecules strike one another and hit the rubber membrane. The membrane vibrates, which causes the mirror to wiggle. The laser light bounces off this wiggling mirror, tracing out various shapes and patterns that we can see.
Different amplitude and frequency of sounds coming from your mouth in turn causes different shapes and patterns.
Some shapes look chaotic, others more regular and repeating. Various frequencies will cause the rubber membrane to dance around in resonant vibration modes, in effect creating fluctuating waves. This will be fun for students to learn and play.

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