naturerecordists
[Top] [All Lists]

Re: sound wavelengh and parabola size

Subject: Re: sound wavelengh and parabola size
From: Walter Knapp <>
Date: Mon, 17 Feb 2003 21:00:47 -0500
Jim Morgan wrote:
> I ran a quick test on my dual science Telinga and found that at 50 and 60=
 Hz
> the gain was the same, however at 80 Hz there was a very noticeable incre=
ase
> in gain and at 200 Hz even more gain. All four frequencies were originall=
y
> the same power level.
>
>
>
> So what I seem to be getting is a gain that increases exponentially with
> frequency but with the lower frequency gain flat from 50 to 70 Hz. Didn't
> test below 50 or over 200 Hz.

I would expect a gain falloff like this. Probably all the way up to the
650 hz or so there will be some increase.

You do have to account for the mic frequency response in figuring out
how much is parabola. And I assume you were using it without bass rolloff.

Then, for picking up from distance we have to account for the
attenuation of sound at different frequencies with distance. Since lower
frequencies carry better it may all be a wash. Which is pretty much what
I've found out in the field recording. The higher frequency stuff cannot
be picked up from near as far as the low stuff with the dish.

Walt




________________________________________________________________________
________________________________________________________________________

<Prev in Thread] Current Thread [Next in Thread>
Admin

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU