Transform: Visualizing the Audio Spectrum

An application of Fourier transforms is an audio spectrum analyzer. A spectrum analyzer is used to view the frequencies which make up a signal, like audio sampled from a microphone. Let’s make the hardware visualize audio frequencies by changing the intensity of LEDs based on the intensity of audio at certain frequencies.

The video below shows the spectrum display listening to powerful orchestral music with a sample rate of 4000 hz, 40 minimum decibels and 60 maximum decibels. You can see the effects of instruments playing at different frequencies and how the LEDs representing those frequencies respond.