21 Sep
2022
21 Sep
'22
5:35 p.m.
On Wed, Sep 21, 2022 at 02:02:58AM +0200, Michael Jarosch wrote:
After that I took a
paper bag to create an impulse, about 50cm away from the NT-SF1.
If the room is big enough, you could use a larger distance.
This will reduce the amplitude of the the impulse but not
the room response, so you could have a better S/N ratio.
A paper bag (or balloon) is not ideal, there are alternatives,
see below.
The only tool in my procedure that wasn't free and
open was Rødes Soundfield
PlugIn, so I had to use some tricks to get manufacturer proven A-to-B
conversion of my recordings.
There is NT1 preset available for tetraproc (real-time A/B processor, Jack)
and tetrafile (file processor doing the same). I can send it if you want.
The method of choice today is not to use balloons or pistols, but
a logarithmic sweep signal and deconvolution with the inverse sweep.
This will give you
1. A more correct result, since the spectrum of the test signal is
exactly known (apart from the speaker used to play it),
2. A much better S/N ratio since the test signal can be several
seconds long so it has much more energy at the same amplitude as a
popping balloon.
Ciao,
--
FA