[linux-audio-user] Audio 3-D Demo --- Any Interest in Software?

R Parker rtp405 at yahoo.com
Mon Jan 5 21:33:23 EST 2004

--- Steve Harris <S.W.Harris at ecs.soton.ac.uk> wrote:
> On Mon, Jan 05, 2004 at 01:49:41 -0800,
> davidrclark at earthlink.net wrote:
> > To summarize a little bit: I can do a lot of
> different things here, 
> > depending upon what people are interested in.  I
> can try to write a 
> > plugin that applies impulse response functions
> that I have generated; 
> > I could perhaps make available the programs for
> producing them; I 
> Making available software that generates the
> impulses seems like a good
> start - that way they can be used with brutefir or
> similar, and the
> roughtness of your software is not an issue for the
> time being.

I don't understand how impulse response (IR) works. I
know you fire off a sound/impulse and then the
response is used to tell calculate the properties of
your room. Will IR tell me that the average/desirable
Sabin value from 20Hz to 4KHz for a .3 reverberation
time in a 17X14X7 room is 148.6?

A fundamental problem I see with IR is that the
accoustical values of good rooms are being applied to
signals that are created in very poor accoustical
environments where frequency responses in the audible
range are not flat. In this scenario, only half the
problem is being addressed. This might not be a
problem with IR as much as it is a mis-use or
underutilization issue.

Almost everyone on this list has a recording studio in
an untuned room. When you record a signal in a room,
using close mic techniques or not, you're recording
the sound of the room and the source. The chances are
very good that the untuned room sounds like crap and
you probably don't know it. You are recording those
bad frequency responses. So, what good does it do to
put that poorly recorded source into a great room?

My point is that great room modeling, reverberation
and echo tools are "the cart before the horse."

I'd suggest that the first thing to deal with is
correcting these bad rooms with Virtual Rooms. You
know, crap in equals crap out.

It doesn't matter whether we use IR or a $9.00 tape
ruler and the known Sabin values and surface area for
the materials of each users untuned recording studio
to determine what needs to be corrected before the
signal is recorded.

I don't have a clue what Audio 3-D is. It sounds like
part of its usefulness could be room modeling. If
that's true then create a LADSPA plugin that can sit
in every input channel of every bedroom studio in the
world and adjust the frequency and reverberation
responses to KNOWN and useful values. If you do this,
many many people can forget about learning to cut
400Hz and 1 and 2kHz because those problems won't be

I know Virtual Rooms aren't particularly sexy and
don't expect them to win a race against the natural
impulse to examine the bra section of the Sears
catalog but what the heck. The question I can't answer
is, can Virtual Rooms sounds as good as physical rooms
that are tuned?

Ron "section undergarments, page 42" Parker

> - Steve

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