The microphone turns the sound waves into an analog electric current which varies in voltage the same way the sound wave does in pressure. However, if the variations are periodic (repeat over time) th...The microphone turns the sound waves into an analog electric current which varies in voltage the same way the sound wave does in pressure. However, if the variations are periodic (repeat over time) the oscilloscope can make these variations visible by repeatedly plotting the same variation over and over on the screen. Note that oscilloscope pictures are time graphs of the sound wave; the oscilloscope does not show the space picture of the wave.
