Digtizing sound

Sound waves create pressure variations in the medium through which it travel. The microphone generates a voltage proportional to the pressure change. You can consider the microphone as a pressure sensor, but working only for time varying pressures.

Objective

Digitize sound signals from a microphone, and measure its frequency. Use the Piezo buzzer or any other source of sound like a tuning fork.

Procedure

Enable CheckButton MIC and it's amplitude and frequency display.
Position the buzzer facing the microphone
Set WG to 1000Hz, change it and watch the MIC output
Use a whistle instead of the buzzer
Press 'Fourier Transform' while signal is steady to analyze it.

The microphone output is shown in figure.

Discussion

The ability to capture sound and measure it's frequency leads to several experiments. Making sound by blowing air in to one end closed tubes can be used for measuring the velocity of sound in air.