linuxaudio.org

On 01/07/2011 12:58 PM, fons@kokkinizita.net wrote:

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> 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.

need to double check, but iirc i did hear a very pronounced (read:

unbearable) boominess on my organ recordings when listening to them on

my <4m array in second order without NFC...
> What you get in that case is a velocity field that

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> does not match the pressure in level,

this i understand.
> and more important - in

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> phase, and this sounds very unnatural.

this is news to me. where does this phase delay come from?
> I'm pretty sure that uncompensated NF effects in reproduction

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> systems are partly to blame for the 'you can't hear the direction

> of LF sources' myth.

interesting hypothesis.
i guess the myth is more correctly formulated as "you can't localize

anything except some select and very obvious mid-frequency cues in AB

stereo". of course, bose and friends would jump on this to sell

ridiculously small satellites with woofers going up to 300 hz :)
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