Different amplitude and time distribution of the sound of light and classical music

Several pieces of different musical kinds were studied measuring A(t), the output amplitude of a peak detector driven by the electric signal arriving to the loudspeaker, which was digitized by a PC with a frequency rate of 100 samples/s. Fixed a valuable threshold (Ā = 100mV), we considered N(A), the number of times that A(t) > Ā, each of them we named event and N(t), the number of events whose time interval from the successive, was t. In this paper some N(A) and N(t) distributions are displayed in the reported bilogarithmic plots, which allow us to draw these interesting conclusions: jazz, pop, rock and other popular rhythms, that is light music, show noise-distribution, while classical pieces of music are characterized by more complex statistics. In particular, we report the extraordinary case of the aria “La calunnia è un venticello”, from “Il Barbiere di Siviglia” by Gioacchino Rossini. The words of this aria describe an avalanche process, calumny, which increasing and increasing, becomes “an earthquake” and its music shows N(A) and N(t) distributions which are typical of avalanches process, that is the hall-mark of critical systems, just as real earthquakes.