> On both plots, the horizontal axis represents time. In the bottom image, the vertical axis represents frequency and pixel color represents intensity. The aut

> On both plots, the horizontal axis represents time. In the bottom image, the vertical axis represents frequency and pixel color represents intensity. The author criticizes the Wikipedia article on the subject being too complex, and yet dives straight into the spectrogram of the audio signal as the first picture on the page! And the first equation is the complex exponential representation of the Fourier sum... The Digital Signal Processing book of Proakis and Manolakis does a perfectly good job of explaining what DFT (and everything else around this matter) is. But there are no shortcuts around it; you still have to understand the Sampling Theorem (aliasing), Fourier series of continuous periodic signals, frequency-domain sampling of Fourier transforms, etc. It took me a while to (somewhat) understand all the nuances of Fourier series and transforms of continuous and discrete signals. And the DFT is a whole layer of theory on top of that. I don't imagine a simple explanation of that begin feasible. However, a more readable or coherent explanation is, of course, always possible.