[mus422] HW3: Hint on SPL computation

[François Germain]

Hello class,

It seems that some of you are confused by the SPL formulas so here are 
some elements to help you do it right:
*The SPL curve we are asking you corresponds to _a vector with one value 
for every frequency line_ of the transforms.
*The summation $$\sum_{peak}$$ present in the formula corresponds to a 
summation that would include, in addition to a given line where a 
sinusoid is present, neighboring lines where the energy of the sinusoid 
would have "leaked". In the general case, when you want to calculate the 
SPL value of any given line $$k$$ of an FFT/MDCT without discriminating 
peaks and non-peaks, _the summation reduces to a single value_ $$|X(k)|^2$$.

Best,

-- 
François Germain

Teaching Assistant / PhD Candidate
Center for Computer Research in Music and Acoustics (CCRMA)
Stanford University

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