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Re: artifact in spectrogram created using Raven

Subject: Re: artifact in spectrogram created using Raven
From: "vickipowys" vpowys
Date: Sun Jul 15, 2012 5:32 pm ((PDT))
Hi Laura,

Welcome to the group!

I think you had the Automatic Gain Control turned ON, for your
recorder.  For nature recording you should always use Manual Gain,
set it at a fixed level so that the wanted sounds do not clip.  Auto
gain gives a noise pumping effect, every time a bird calls the gain
quickly goes down, then gradually up again.  This is how the Raven
jpg looks to me.

However there was no sound sample in the Nelson's Sparrow folder, to
test my theory.

Assuming you are studying different dialects rather than relative
loudness, your sound files should be useable although there may be
some clipping at the start of a birdcall, before the auto gain kicks in.

What recorder were you using, and what microphone/s?



Vicki Powys
Australia



On 16/07/2012, at 10:11 AM, laura.hilberg wrote:

> Hi everyone,
>
> I haven't posted here before, but I've been following this forum
> for a few months now. I am finishing up my Master's degree in
> conservation biology, and my thesis is a dialect study of the
> Nelson's Sparrow (found on the coast of New England and inland from
> North Dakota up through interior Canada).
>
> I just returned from my field season, recording sparrows in
> multiple locations in Maine. I'll be analyzing my recordings using
> Raven, and one of the first things I noticed when I opened it up
> was a strange white space underneath the song, which roughly
> correlates with amplitude and pitch. It looks like a white echo - a
> silent space in a background otherwise full of traffic and wind
> noise. Since I know that the traffic and wind noise didn't
> disappear, I'm assuming that it is not really there? "I uploaded a
> picture and sound clip in the "File" section of the Yahoo Group in
> a folder called "Nelson's Sparrow").
>
> The white space is always there to some degree, but it is much more
> extreme in the loud songs, in which I can also hear a little bit of
> a bubbling sound (hard to describe). My only idea is that my gain
> was turned up too high and that distorted the sound at times?
>
> I realize that I don't have all the right vocabulary or a deep
> understanding so this might be hard to follow - does anyone have
> any thoughts or ideas?
>
> Thanks,
> Laura H.
>







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