
A command available in the Query menu if you select a Sound object. The Info window will show the standard deviation (in Pascal) of the sound pressure within a specified window. If the sound contains less than 2 samples, the value is undefined.
The standard deviation is defined as
1/(t_{2}t_{1}) ∫_{t1}^{t2} (x(t)  μ)^{2} dt 
where x(t) is the amplitude of the sound, and μ is its mean. For our discrete Sound object, the standard deviation is approximated by
1/(n1) ∑_{i=m..m+n1} (x_{i}  μ)^{2} 
where n is the number of sample centres between t_{1} and t_{2}. Note the "minus 1".
© ppgb, November 23, 2004