# Meaning of phase in Fourier Transform of audio signal

I'm looking at the Fourier Transform (really, at a sliding DFT) to analyze (visually and intuitively) the frequency components of a sound over time. But the DFT produces complex numbers, and I'm not sure how or whether to visualize them.

Should I just graph the magnitude of the result?

I've tried letting the argument/phase of the resulting number affect the hue of the graph, but it just looks more or less like a rainbow oil spill. It doesn't seem to help me understand anything about the sound.

Or would just dropping the imaginary part convey just as much?

• For future reference note that dsp.stackexchange.com is now out of beta and is probably a better fit for this type of question. – Paul R Sep 22 '11 at 8:09

Yes, just use the magnitude of the FFT output ($\sqrt{re^2 + im^2}$) - this gives you an estimate of the power spectrum. Phase information is generally of little interest in this context.