Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec

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From: <fons@...>
To: <linux-audio-user@...>
Date: Saturday, January 8, 2011 - 2:30 am

On Sat, Jan 08, 2011 at 01:39:17AM +0100, Jörn Nettingsmeier wrote:

> >Not exactly. For a well-designed decoder the pressure at LF will

That is very well possible. It means that you don't have the real
pressure, not even at the sweet spot. Which is to be expected if
your room isn't free of LF reflections, as most are.

> >What you get in that case is a velocity field that

It's just a property of the higher order components in the near
field. If you look at the amplitude and phase plots of the higher
order NF effects, it's very evident that there is quite a large
phase shift even before the amplitude starts to rise by any
significant amount. Even for first order the +3dB point has
45 degrees phase shift - like a first order filter.

Also if you look at Moreau's 'useful bandwidth' filters for
synthesising near sources, you'll see that none of them has
more than 3 or 4 dB gain before going down steeply for lower
frequencies. This means that it is not the very high LF gains
of the higher order components that create a near source, but
the phase shifts.

> i guess the myth is more correctly formulated as "you can't localize

With Bose you'd be lucky to localize anything at all :-)

Ciao,

--
FA

There are three of them, and Alleline.

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Messages in current thread:
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, Jörn Nettingsmeier, (Fri Jan 7, 9:56 am)
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, Jörn Nettingsmeier, (Fri Jan 7, 10:10 am)
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, Jörn Nettingsmeier, (Sat Jan 8, 12:39 am)
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, , (Sat Jan 8, 2:30 am)
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, Jörn Nettingsmeier, (Sun Jan 9, 9:14 pm)
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, Jörn Nettingsmeier, (Sat Jan 8, 12:24 am)
Re: [LAU] ambisonics: fons ambdec and muse.demon.co.uk ambidec, Jörn Nettingsmeier, (Thu Jan 6, 11:11 pm)