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Re: ITU worst case for 5.1

The sweet spot for a 5.1 or 7.1 system is entirely dependent on the production method used to make the actual material to be played back.

We did some very primitive work on this back before the AT&T Labs diaspora in 2002, unfortunately we did not compare coincident 5.0 to nearly coincident 5.0, rather we compared nearly coincident 5.0 to nearly coincident 2.0.  In that we found that for inexperienced listeners, the area for 5.0 was about 3x the size of the listening space for 2.0, and for experienced listeners, it was more like 6 times larger, in fact corresponding to any reasonable seat in the room that was more than about 1 meter from a loudspeaker.

Given the current propensity for intensity-only panpots justified by some 20 year old work on 2-channel panpots that can be refuted by a single female vocalist at the 1/4 or 3/4 position (the high frequency and low frequency locations conflict nastily), it is possible that many 5.0 or 5.1 mixes one gets require exact center seating :(  which is even more constraining than a 2-channel panpotted system.

I don't have the citation offhand but it's on my web site (home.comcast.net/~retired_old_jj, I think it's Johnston and Lam as authors. Sorry, it's been a while.


James D. Johnston  (jj@xxxxxxx)

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-----Original Message-----
From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Kevin Austin
Sent: Monday, March 29, 2010 5:07 PM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: [AUDITORY] ITU worst case for 5.1

Most of the home theater 5.1 systems I have seen in friends' houses have had the speakers placed wherever there happens to be a space for them. By the definition I would take it that there is one "best" position, and several hundred bad and worst case positions. In many situations I've seen, a 1.4 meter sweet spot is unusually large.


> Date:    Sun, 28 Mar 2010 17:24:31 -0400
> From:    Nils Peters <nils.peters@xxxxxxxxx>
> Subject: ITU worst case listening position - how?
> Hi,
> I hope someone from this list can help out, the ITU people could not sufficiently answer my question.
> The ITU-R BS.1116-1 recommendation "METHODS FOR THE SUBJECTIVE ASSESSMENT OF SMALL IMPAIRMENTS IN AUDIO SYSTEMS INCLUDING MULTICHANNEL SOUND SYSTEMS" (p.18, Figure 7) defines the typical 5 channel surround loudspeaker setup including the best (central) and worst case listening positions.
> Here my question:
> What are the underlying assumptions/calculations that make these specific listening positions to the "worst case listening positions" ?
> The text on the same pages also defines the recommended listening area which has a radius of 0.7 m around the central position. I am also wondering where this number comes from.
> thanks for any comment.
> Nils

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