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Old 28th January 2010, 03:49 PM   #181
gedlee is offline gedlee  United States
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Originally Posted by markus76 View Post
We're talking about how polar maps correlate to perception. It is out of question that the indirect sound field does affect perception. But then, distortion affects our perception too

Best, Markus
"How" is not know and not of that much interest. The important thing is that it does correlate, the better the directivity control the better the subjective preference. The connection has not been made one-to-one, but all data suggests that it is there. There is no data (that I know of) that refutes this.

Distortion, on the other hand, is quite the contrary. All studies have concluded that it is a minimal thing in loudspeakers and even Floyd and Sean state this. Only agregious amounts of distortion in a loudspeaker are an issue. Once these are brought down to reasonable levels then its other things, like polar response, diffraction and dynamics that are the significant issues.
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Old 28th January 2010, 03:55 PM   #182
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In the "Predicting Listener Preference from Measurements," section of Toole's book and in many other places looking at pro speakers there is a "Directivity Index" given in decibels usually scaled from 0-10 dB or something like that. Is that scaling how far down the response would be at 45 degrees? I don't actually see anything else about polar response in the data. There are indication of the polar response, but nothing direct. There is measurements at the "Listening Window", "Early Reflections", "Directivity Index" and "Sound Power" given, but no polar response graphs.

Thanks again,

Dan
These are all things that depend on the polar response. Floyd and crew believe that the entire polar response can be reduced to the three or four curves that they show. I do not discount this, it might be true, but I do have some concerns. At any rate since what they do show is contained within a polar map, but on the other hand their data presentation does not show all the issues that one can see in the polar map, I do not see why one would not want to see the greater detail as opposed to the lessor. In Harmons case there was a strong incentive to "simplify" the data presentation so that marketing could understand and utilize it. There was a serious attempt to make the presentation as simple to follow as possible. I am not attempting to do that. I have run a Toole-like graph on my speakers and it doesn't show anything new. But I would dearly love to see some of the data that he has in a polar map. That would be most interesting.
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Old 28th January 2010, 04:03 PM   #183
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"How" is the only thing of interest if we want to assess data qualitatifely.

As to distortion I agree but this shouldn't lead to the conclusion that loudspeaker maker don't need to show any distortion data at all. I'd like to see a complete dataset. How can a customer be sure that a device works as expected without knowing all the facts? My 2 cents.
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Old 28th January 2010, 04:44 PM   #184
gedlee is offline gedlee  United States
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Originally Posted by markus76 View Post
"How" is the only thing of interest if we want to assess data qualitatifely.

As to distortion I agree but this shouldn't lead to the conclusion that loudspeaker maker don't need to show any distortion data at all. I'd like to see a complete dataset. How can a customer be sure that a device works as expected without knowing all the facts? My 2 cents.
If you can show me some measure of distortion that correlates with subjective - otherwise its just lines - then I'll measure it. I know - the GedLee Metric - maybe someday I will, but that measurement takes capabilities that aren't generally available. Thats why I liked HolmImpulse because it does make the necessary data available, but it takes a lot of further processing. What I have done is to find the Gedlee Metric for some loudspeakers and according to our data, the nonlinearity would not be audible. If you are interested in "facts", then the fact is that nonlinearity in a loudspeaker is irrelavent. Accept that fact first and your other comments go away.

"How" might be different to the two of us. "How" to me means: "How does our brain use the sound signals to perceive different sound in different ways." Thats "how" and, to me, its too deep. What I want to know is: "What measureable aspects of a loudspeaker correlate with subjective impression, what is the correlation, and what do I need to do in my loudspeaker designs create the best subjective impression?." Not one of these is not a "how" question at all, but it may be semantic.
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Old 28th January 2010, 04:50 PM   #185
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it may be semantic.
It is
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Old 28th January 2010, 04:52 PM   #186
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These are all things that depend on the polar response. Floyd and crew believe that the entire polar response can be reduced to the three or four curves that they show. I do not discount this, it might be true, but I do have some concerns. At any rate since what they do show is contained within a polar map, but on the other hand their data presentation does not show all the issues that one can see in the polar map, I do not see why one would not want to see the greater detail as opposed to the lessor. In Harmons case there was a strong incentive to "simplify" the data presentation so that marketing could understand and utilize it. There was a serious attempt to make the presentation as simple to follow as possible. I am not attempting to do that. I have run a Toole-like graph on my speakers and it doesn't show anything new. But I would dearly love to see some of the data that he has in a polar map. That would be most interesting.
I actually think a polar map would be simpler for the end user--it leaves less to guess about.

Can anyone briefly explain the directivity index graph? I've looked on line, but all I find is equations. yuk. Maybe it's how much less total output is occurring at those? or how many dBs the speaker is down at 45 degrees? or something else? Those things would be more useful if I knew what they were telling me. Sorry of this is getting too far from the White Paper. It keeps giving me more questions.

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Old 28th January 2010, 04:59 PM   #187
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The directivity index shows the averaged level of sound radiated in all directions normalized to the level on the 0 axis.

Best, Markus
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Old 28th January 2010, 05:43 PM   #188
Key is offline Key  United States
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There is no data (that I know of) that refutes this
I think it might be because no one is looking very hard. I think Linkwitz assertion that his omnis are almost perceptually identical to his dipoles at least points in this direction. Or points to an alternative causation - most likely involving the brain reconstructing the sound field or simply ignoring measurable differences in room modes and reflections in certain situations.

Are there any free links to studies on distortions? And when you say distortions are we including or excluding inter-modulation?

It seems clear to me that people more than not actually like distortions. A lot of experienced sound engineers I have met prefer gear with copious amounts of euphonics compared to the analytical counterparts. I have gotten around to benchmarking various mastering and mixing chains and from everything I have seen and tested I tend to think that recordings with very little HD are very rare.
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Old 28th January 2010, 05:54 PM   #189
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an alternative causation - most likely involving the brain reconstructing the sound field or simply ignoring measurable differences in room modes and reflections in certain situations.
Exactly. "Binaural decoloration" could be one of the reasons why polar maps won't be that meaningful at all.
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Old 28th January 2010, 05:57 PM   #190
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Could be. I think it's more about coverage if you are talking about projecting back an image. I have no problem as I sort of hinted about with localization in my setup vs binaural. The only difference seems to be a lack of artifacts. But I am going to give the binaural thing another try correcting the transfer function. I just don't think in-head-localization for me anyway will go away until I use a headtracker.
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