Using Fourier Transform to Find the Frequencies in a Sound Wave

by Sage Keesler

Submitted : Spring 2019

In this project, we wanted to find all the frequencies present in a sound wave. The sound wave was a combination of random keys played on a keyboard and recorded. This was done using Fourier transform. Because of how complicated it would be to describe this sound wave using a mathematical expression, MatLab was used to graph the wave on an Amplitude vs. Time graph, then that graph of the sound wave was used to make the Fourier transform of the sound wave which is graphed on an Intensity vs. Frequency graph. This allows us to find every frequency that was present in the original sound wave, as they appear as spikes at their respective frequency on the Fourier transform. The results were determined to be practical by comparing their frequencies to the frequencies of musical notes since the source of the wave was from a keyboard. This concept and method has many practical uses, such as signal processing, sound editing, and Doppler radar. It also is the main component to proving Heisenberg’s uncertainty principle.

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