Re: [LAU] placement.

Fons, you've described my crude experiment with this. Left, Centre, Right,
and a complete IR for 'global' as the tail. I'll have to experiment some
more, and possibly truncate the 3 short irs further, but i'm getting the
idea in relation to a more realistic representation, however crude it may
be.

A question here gentlemen.

With an WXYZ setup, what do those represent? Left/Right/Front/Rear?
So any signal in would be a composite of position based on the strength of
gain between 2 or more points?

Is it a 'box' in effect, so any point represented would be a positional
calculation based on all 4?

Or do i have this wrong?

I'm off to try out the YorkMinster conf file, and see if that gives me any
listening clues.

Alex.

On Tue, Jan 20, 2009 at 9:03 PM, Fons Adriaensen <fons@email-addr-hiddenwrote:

> On Tue, Jan 20, 2009 at 06:34:27PM +0100, Jörn Nettingsmeier wrote:
>
> > to clarify things, there are no "short" or "long" IRs. what fons means
> > is: the early reflections are the most characteristic aspect of a room,
> > and they affect localisation the most.
>
> I don't think I can really agree with the first part of this
> statement, but the second part is certainly true.
>
> > therefore, if you want to have
> > ultra-realistic reverb, use an IR that was measured with the speaker
> > where your intended instrument is and a soundfield microphone where the
> > listening spot is. of course, in practice this is not done.
> >
> > so instead you use one reverb IR instead. it can be short (tail
> > truncated) to save CPU, because the tail is decorrelated (blurred) and
> > does not provide localisation cues, hence it would be wasteful to render
> > it in b-format.
>
> What I suggested is:
>
> * use a short IR, containing the early reflections, for each
> source position, or a at least a small set of them for
> different areas (e.g. left, center, right),
>
> * manipulate the delay of this in function of source distance
>
> * use the same long IR, containing the reverb tail, for all
> sources.
>
> Of course, the real reverb tail is different for each source,
> but you can't hear the difference. Only its statistical
> properties (such as the reverb time, etc) matter.
>
> But I wouldn't say it is wasteful to render the reverb tail
> in B-format, on the contrary, doing that makes it very realistic.
>
> > if you can make it to lac2009, let's talk this through over pizza
> > (that's how i learned my first steps in ambisonics from fons, and it
> > works suprisingly well).
>
> And pizza is easy to get here.
>
> > as i said, i would recommend against attempting such a split reverb
> > method, because very likely things will go haywire at some point.
> > better bribe fons :)
>
> I have some jconv configs containing separate short IRs for
> different source positions, and a single reverb tail. They
> need some reworking (*), but when you are in Parma we can
> play with them.
>
> (*) For example, removing the direct sound can be a bit
> more complicated than just cutting it off. In most cases
> the LF response of the direct sound continues during the
> early reflection period (at very low level, you don't see
> it in the IR). Just cutting away e.g. the first few ms can
> leave enough LF energy from the direct sound to result in
> a bass-heavy IR.
>
> Ciao,
>
> --
> FA
>
> Laboratorio di Acustica ed Elettroacustica
> Parma, Italia
>
> O tu, che porte, correndo si ?
> E guerra e morte !
>

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Received on Wed Jan 21 00:15:01 2009