Hello Michal!
A starter gun is/was used often, but isn't the best of ideas, if you can
help it. The energie in all the different frequency bands of the reverb is too
low. If your friend is willing to use Aliki, then she'll have a frequency
sweep done with a sine wave. Of course for that, she'd also need a speaker or
two to let that blare through the space. Nice thing about it: The speaker
doesn't have to be top quality, it can distort a little without damaging the
resulting IR.
As to microphones: Not aexactly sure, but there are mics preferred for
ambient recordings. Otherwise I'd say every mic, that can pick a good deal of
frequencies with a relatively flat response. Not sure about the
characteristic. I suppose something not to narrow angled.
I hope, that at least has helped a bit.
Kindly yours
Julien
--------
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