supplemental if you care about details<p><a href="https://en.wikipedia.org/wiki/Joseph_Fourier" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Joseph_Fourier</a><p><a href="https://betterexplained.com/articles/an-interactive-guide-to-the-fourier-transform/" rel="nofollow noreferrer">https://betterexplained.com/articles/an-interactive-guide-to...</a><p><a href="http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/fourier.html" rel="nofollow noreferrer">http://hyperphysics.phy-astr.gsu.edu/hbase/Audio/fourier.htm...</a>