Voss and Clarke

On the left, Voss and Clarke plot Log(frequency) on the x-axis, vs Log(loudness fluctuation power spectrum). On the right is a similar plot for the pitch fluctuation power spectrum, a rough indicator of melody.
The graphs are The graphs are
(a) Scott Joplin piano rags, (a) classical,
(b) a classical radio station, (b) jazz and blues,
(c) a rock radio station, and (c) rock, and
(d) a news and talk radio station. (d) news and talk,
Below 1 Hz, the match to the reference 1/f graph is good. all averaged over about 12 hours.
For (a), the signal was averaged over an entire recording.
Joplin rags have a strong rhythm, so the power spectrum has a considerable amount of structure between 1 and 10 HZ.
Below 1 Hz, we are detecting long-range correlations in the music, and the spectrum agrees well with 1/f.
Again, the match with 1/f is good, though the talk station exhibits peaks at the time scale of a single sound, and at the time scale of the average time a person speaks.
The rock graph (c) begins to flatten out on time scales longer than a single composition.
Classical compositions tend to be longer; the data presented do not extend beyond the average length.

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