I read the explanation several times, but I don't know how to interpret what I'm looking at. It's the third graph on this page, under the heading Spectrum (the paragraph above the graph explains it). Did they take a section of the recording and average the frequencies and amplitudes? Could someone please walk me through how they constructed the graph and maybe tell me what one point says? BTW, I'm studying this for phonetics. At the moment, I know very little about acoustics or physics, so any extra explanation about sound waves and their properties that are being measured here would help. For instance, I only have a fuzzy idea of what frequency, amplitude, and phase are.