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Re: Introduction...

Subject: Re: Introduction...
From: "Avocet" madl74
Date: Sat Jun 11, 2011 7:05 am ((PDT))

Welcome to the list. It's full of ideas and the odd controversy. :-)

It sounds like a good kit and the only comment I would make is that
the ORTF array is related to the "dummy head" types of array and gives
its best effect on headphones. If you are analysing the recordings, a
mono front signal mix of the two tracks will give a comb filter effect
at some angles due to the time shift which may or may not show up. The
first extinction frequency will be about 1.5KHx at 45deg. Your ears
will not hear this on headphones. You can test this with compresssed
air hiss - which gives "blue noise" - and a power spectrum analysis.

For a directional recording for measurment rather than for listening I
would compare the ORTF with a coincident cardioid capsule array with
one mic over the other with horizontal directional angles from 90deg
to 120deg. The time differences that the ear responds to is in
fractions of a millisecond, not easy to measure.

If you want to go to town on direction recording consider four
coincident or near coincident cardioids or two double cardioids like
two AT 8022's. I've just been recording a jackdaw nest in a chimney
using two stereo recorderas for inside and outside and synchronising
them easily using Audacity so you can try out the idea without a

I'm using gun mics for a lot of my recordings and I would not advise
taking off-axis measurements from these as their frequency rsdponse
off axis is very wonky.


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

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