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Re: bat recording with AT4022 mic

Subject: Re: bat recording with AT4022 mic
From: "Avocet" madl74
Date: Wed Jun 1, 2011 7:16 am ((PDT))
> I have recorded a bat with a standard mic, so it's not as good as 
> you would get with a ultrasound mic or a bat detector of some kind.

Wanna bet? The mics in affordable bat detectors are no great shakes 
either. They are often Knowles capsules or similar which still have a 
response at bat frequencies but by the time they are HF boosted, they 
get quite hissy. Many electret mics have a useful extended HF 

> What is the best way to work with the file in post?
Any suggestions?

Fork out two zeroes for a specialist bat analysis program or use free 
Audacity which gives you all you want. Parameters are:

  Call start frequency
  Call end frequency
  Repetition rate and pattern - regular or irregular
  Shape of call - FM (sweep) or CF (constant frequency)
    or a combination - a "hockey stick" call

On Audacity you look at:

  Overall call pattern waveform with timing
  Normalise the call or part and display the sonogram <spectrum>
  Select a single call and display the power spectrum
    <Analyse - Plot Spectrum>

That's about all that a commercial bat package does. The rest is info 
and a library of bat species calls.

See Wiki "Bat detector" and Wiki "Bat species identification" I 
expanded the types of bat detector and put some sample displays on the 
second one.


David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce

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