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,
|(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.
Return to Voss and Clarke.