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

fons at kokkinizita.net fons at kokkinizita.net
Fri Jan 7 11:58:18 UTC 2011

On Fri, Jan 07, 2011 at 11:10:41AM +0100, Jörn Nettingsmeier wrote:

> for those non-ambiheads wishing to follow this discussion:
> the near-field effect in ambisonics results in a bass boost. it's
> caused by the speakers. ambisonic theory (without NFC) assumes plane
> waves, i.e. speakers that are very far away, so that the wave fronts
> are not curved. since they are curved in practice, you get the bass
> boost. the same thing is responsible for the well-known proximity
> effect on directional microphones.

Not exactly. For a well-designed decoder the pressure at LF will
be proportional to W, even without NFC, and should not have any
bass boost. What you get in that case is a velocity field that
does not match the pressure in level, and more important - in
phase, and this sounds very unnatural. 
I'm pretty sure that uncompensated NF effects in reproduction
systems are partly to blame for the 'you can't hear the direction
of LF sources' myth. 



There are three of them, and Alleline.

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