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Re: Normalizing calls in AviSoft

Subject: Re: Normalizing calls in AviSoft
From: "Raimund" animalsounds
Date: Mon Jan 11, 2010 7:10 am ((PST))
alizaleroux wrote:

> What I'm trying to do is extract individual calls that occur in a train o=
f 3-6 calls. I need to put these calls into separate wav files yet measure =
their original intercall intervals accurately in the original file. I don't=
 want my interval measures to be affected by the differences in overall cal=
l volumes. If I have to do it all individually some calls might appear shor=
ter/ longer simply due to overall amplitude. Due to background noise I inte=
nd labeling each call by hand so as to not confuse Avisoft's automatic meas=

Hi Aliza,

I think that you probably don't need to put the individual calls into separ=
ate wav files. The Automatic Parameter Measurements tool in Avisoft-SASLab =
Pro can already handle varying call amplitudes. You just had to use the "El=
ement separation" option "automatic (two thresholds)" that employs an addit=
ional threshold (relative to the peak amplitude of each call) for locating =
the start end end of each call. However, if the amplitude differences were =
too high, it might indeed be required to treat the individual calls separat=
ely. If you are unsure, you could send me (to support <at> one=
 of your recordings as an email attachment. I would then try to figure out =
the best settings for your specific application.

> About CORRELATOR -- are the comparisons not affected somewhat by amplitud=
e? I realize that the program examines the spectogram as a whole, but it fe=
els like calls should be at least within a small amplitude range instead of=
 all over the place... Is this true, or can I compare soft and loud spectro=
grams (of the same call type) without fear? I want to look at certain indiv=
idual call parameters but running the correlator in addition to this certai=
nly can't hurt.

The CORRELATOR does not care much about different spectrogram amplitudes be=
cause there is already an inbuilt normalization procedure that takes care o=
f that issue.


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