Re: [Audacity-nyquist] More acoustic analysis, time weighting FAST and equivalent level

[George J. <geo...@gm...>]

Wow this is great.  I haven't had time to deconstruct it all - I think I get
somewhere with these things then all of a sudden there is a line with an
orgy of parentheses.  I understand better getting information back out to be
visible.

Anyway let me ask a few things to see if this is a way forward.
>
>
> (setq saf2
> (mult 0.000001
> (snd-avg (snd-biquad (mult sa sa ) 1 0 0 (exp (/ 1 (mult (snd-srate sa) -
> 0.125))) 0 0 0) 441 441 OP-AVERAGE)
> )


I think after this line we have a new "sound" called saf2 that consists of 8
samples per second.


> ; Length of the downsampled pressure squared signal
> (setq mlength
> (snd-length saf2 99999999999)
> )


By running snd-length it forces all samples into memory - the manual says
"about 4 bytes per sample".

Why about?   Anyway can I then do

     (setq array_of_samples (snd-sample(saf2 7200)))
to get the samples into an array.  (7200 samples in 15 minutes)

Then define a function that sorts the array (will "sort" work on an array or
just a list? - or can we convert it to a list and use "sort") then read out
the 720th element of the array to get the L10?

Thanks again.  I'll try some of these ideas in the next few days.

George