3.29 understand how an oscilloscope and microphone can be used to display a sound wave

A microphone can be used to detect soundwaves

An oscilloscope can be used to display these sound waves.

By plugging the mic into the oscilloscope it can display a sound wave as a trace on the screen.

This displays the wave on the screen and it can tell you how whether it's loud or quiet and high or low pitched. 

Detailed recordings can be made by adjusting the screen so that a square is a known distance. By counting up these squares you can find detailed measurements.