I’ve been doing a lot of signal processing lately (Python tutorial on analyzing .wav files to come) and came upon this nice metaphor for Fourier Transforms, which can help extract information from sound.

**Random dude**: I need to know how many 7’s there are in 49.

**High school algebra student**: Duh, just divide 49 by 7. There are seven 7’s in 49.

**Random dude**: I need to know how many x’s there are in y.

**High school algebra student**: Duh, just divide y by x. There are y/x x’s in y.

**Random dude**: I need to know how much of the frequency 23Hz there is in my signal x(t).

**High school algebra student**: Duh, just divide x(t) by 23Hz. There is x(t)/23Hz amount of 23Hz in your signal.