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Old 14th October 2012, 02:18 PM   #41
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Were the tests double blind?
rcw
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Old 14th October 2012, 02:29 PM   #42
SY is offline SY  United States
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rcw: A few forum participants did a DBT on group delay using files created by Malcolm Hawksford. I wouldn't say it was easy and obvious, but at least two of us did sort them properly. For me, the interesting part wasn't that we could hear the differences (I expected that we could), but the heated reaction of the Golden Ear crew, who refused to even try.

With DBT function available in foobar and a few minutes with sound editing software, it's easy for anyone to determine their own sensitivity.
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Old 5th December 2013, 11:53 AM   #43
keyser is offline keyser  Netherlands
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Quote:
Originally Posted by SY View Post
rcw: A few forum participants did a DBT on group delay using files created by Malcolm Hawksford. I wouldn't say it was easy and obvious, but at least two of us did sort them properly. For me, the interesting part wasn't that we could hear the differences (I expected that we could), but the heated reaction of the Golden Ear crew, who refused to even try.

With DBT function available in foobar and a few minutes with sound editing software, it's easy for anyone to determine their own sensitivity.
SY, I'd like to try that test. Are the files available?
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Old 5th December 2013, 01:21 PM   #44
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In the latest issue of JAES is an article about the audibility of phase distortion, which is mathematically related to group delay distortion.

Talking about the latter: The name of the thread shouldn't be whether group delay is audible - it should actually be about audibility of group-delay DISTORTION.

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Old 5th December 2013, 03:55 PM   #45
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Originally Posted by phase_accurate View Post
In the latest issue of JAES is an article about the audibility of phase distortion, which is mathematically related to group delay distortion.

Talking about the latter: The name of the thread shouldn't be whether group delay is audible - it should actually be about audibility of group-delay DISTORTION.
Charles,

How are "phase distortion" and "group delay distortion" defined?
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Old 5th December 2013, 08:55 PM   #46
Pano is offline Pano  United States
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With the handy-dandy software "rePhase" (see this forum) I can correct the phase of my system bringing to essentially flat. I can hear it - but it's subtle. I guess that's group delay.
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Old 6th December 2013, 06:58 AM   #47
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How are "phase distortion" and "group delay distortion" defined?
The mathematical link between group-delay and phase is that group delay is proportional to the negative slope of the phase versus frequency .
Systems with constant group delay are per se linear phase. I.e. phase-shift is proportional to frequency.
If a system is not linear phase it will not have constant group-delay OTOH. Non - constant group delay means group-delay distortion.
If a system has frequency ranges with rapid phase-changes it even has humps in its group delay.
I made my statement in the former post to indicate that studies dealing with the audibility of phase-distortion can also be indicators for the audibility of groupe-delay distortions to some degree )while pointing to latest study that I know of).
But studies of these things are always difficult to perform and to interprete. Many times one sees citations of the study by Blauert and Laws. IMO credit goes to them for being the first ones dealing with this subject. OTOH it is often cited where it is not applicable IMHO. In their test setup they used a severily bandwith-limited signal (which is therefore having quite some group-delay distortion from the beginning) to which they added peaking group delay distortion with allpass filters. One cannot simply apply their findings to the audibility of group-delay distortion in wideband speakers with crossovers.
My opinion is that it is never bad to keep group-delay distortion as low as possible as long as other parameters are not sacrificed.
Keep in mind that according to information theory a channel with group delay distortion has a lower information capacity than one without group-delay distortion (everything else being equal). But als always in information theory an information channel has to be optimised for matching the source and the sink of the information. If there would exist a mathematical model for the audibility of group-delay distortion it would be easy to design speakers that are blameless* in this respect.

*copyright: D. Self

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Charles
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Old 6th December 2013, 11:28 AM   #48
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Group delay within pass band causes no loss of information, just changes to phase.
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Old 6th December 2013, 01:52 PM   #49
kessito is offline kessito  Netherlands
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Group delay within pass band causes no loss of information, just changes to phase.
I do not agree with this; if you listen to zero-phase loudspeakers, things like percussion have a different (more real) attack sound.

for instance, a snare drum sounds "tok" instead of "tak".
Therefore I think that information does get lost because of phase distortion.

The downside of multiway speakers which are corrected te be zero-phase, is that the of-axis response becomes worse in the transient response, because of the pre ringing that the correction filters cause.

just my 2 cents..

Kees

edit; of course this is a bit symatic, the information expressed as electrical energy doesn't gest lost. A sine sweep is in this way the same as a single impulse, though they sound rather different..

Last edited by kessito; 6th December 2013 at 01:54 PM.
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Old 6th December 2013, 04:44 PM   #50
gedlee is offline gedlee  United States
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Originally Posted by phase_accurate View Post
If there would exist a mathematical model for the audibility of group-delay distortion it would be easy to design speakers that are blameless in this respect.
There is lots of evidence that GD distortion can be audible, and a lot of this evidence says that its audibility increases with increased SPL level - although GD in itself is a linear effect (it's the ear that is not linear).

As to some mathematical model I would suggest reading Greisinger's discussion of this topic as I think that it is right on the money. Its not a proof mind you, but it is a very compelling argument that fits the known data.
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