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Re: bird song

Subject: Re: bird song
From: Walter Knapp <>
Date: Thu, 28 Nov 2002 16:28:45 -0500
Dan Dugan wrote:
> Gerald, you wrote,
> 
> 
>>You mention that the old PA systems were more efficient at
>>projecting sound.  I remember being in the audience of those set ups
>>and would note that the sound had a different quality than today's
>>sound systems.  They would produce sound that was very load but it
>>was not pleasant to hear!
> 
> 
> Exactly. Simple horn speakers are very efficient (around 40%) at 
> certain frequencies, but not "flat" in frequency response; they 
> produce a narrow-band filtered output. Similarly, the voice mechanism 
> of birds is very efficient at certain frequencies and incapable of 
> doing anything else.
> 
> I'm sure it would be possible to use little horn-loaded "tweeters" 
> for reproducing high-frequency birdsong very efficiently--but they 
> would burn out if you played lower frequencies into them!

I don't have to go above 8kHz, in fact for my main target, Pine Barrens 
Treefrogs, 3kHz would be ok.

I've been looking at the small folded horn speakers one typically sees 
on the outside of utility trucks. I know that in that use they don't 
sound like much, but a lot of that is the original source. I've been 
thinking about driving those with a small battery operated amp. They 
should be optimized for voice frequencies, which is similar to what I need.

Walt




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