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Old 17th March 2010, 10:49 PM   #741
graaf is offline graaf  Poland
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interesting thread on gearslutz: Early reflections or not - Gearslutz.com

Quote:
D'Antonio's summary of the history of the evolution of acoustic room models:

Evolutionary Summary

Early Reflections:

· We have oscillated from being unaware of the importance of early reflections
· to emphasizing them in Hidley’s compression ceilings
· to learning of their importance in providing envelopment from Schroeder’s concert hall research
· to removing frontal reflections completely due to comb filtering and image shift in Davis’ LEDE, D’Antonio’s RFZ, Hidley and Newell’s non-environment approaches
· to utilizing rear diffuse reflections for enveloping passive surround sound in D’Antonio’s RPG rear wall
· to re-evaluating the perceptual importance of specular and diffuse reflections in the work of Massenburg, Angus, D’Antonio, Toole, Martens and Moulton

Mid and Late Reflections:

· There has been general agreement in all designs over time that the decay time should be small
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Old 17th March 2010, 11:26 PM   #742
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A "ceiling flodder" would be equivalent to Hidley's compression ceilings from the 70s. Most studios have them ripped out. See Newell "Recording Studio Design"
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Old 18th March 2010, 01:18 AM   #743
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Hmm, let's see, Loudspeakers and room as a system.

Nope, none of the last ten posts had anything to do with the title. Sure was fun weeding through all that useless banter though. I know, why don't you two take a break from this thread. Might do you some good.
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Old 18th March 2010, 01:29 AM   #744
Key is offline Key  United States
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Oh if only.. Actually I think it's pub time.

Anyway back to speaker stuff. On directivity of a loudspeaker and what will work best in a room, give the best illusion etc... I used to think that theoretically the ideal loudspeaker would be omni directional approximately 20-20kHz. I'm not so sure that is exactly true. Not saying it wont work well - it certainly would but that isn't the point.

If you were to take a competent musician and a speaker which replicates the directivity of that musicians instrument in the same room and have them play next to each other the physical replication of the musician would be so similar it would be very hard to tell the difference with a blind comparison. Part of this is that the speaker and player are in the same room but a larger part of this is that it is just analytically very close to the soundfield that you are trying to replicate.

Stereo of course is different and is in part illusion bases (in terms of a phantom image). So I guess to me the ideal loudspeaker would be one that could alter it's directivity in a polyphonic and extremely controlled fashion. It should also be able to control resonance in terms of turning them on and off on a dime in a polyphonic fashion. In other words it's not gonna happen anytime soon.

So all theory aside what should we do now? I think it's subjective but there are certain patterns under the surface of directivity in loudspeakers that we just haven't identified. And if we did have the theoretical speaker which could change directivity we would be able to dial in these differences and hear exactly what is going on. But we have not managed to achieve anything close to this imo. The closest thing I have heard of is Linkwitz with his omni and dipole. Maybe speaker manufacturers have done similar things but I just haven't seen the useful data that helps me as someone who wants to control and make music.

What do mastering engineers do when they can't control all the instruments and are basically unable to make all of them optimized due to the limitations of 2 tracks? I read Steve Hoffman talking about how he goes about mastering and it's basically an acceptance of this problem. I can't remember exactly what he said but basically he concentrates on the stand out instrument. He zones in on that one instrument and tries to make it sound as real as he can make it sound. Maybe some other instruments suffer but that is the compromise that has to be made possibly.

So I guess it's my thinking that the speaker which gives the best illusion of the human voice and it's directivity will be the speaker which performs the most consistently. If you can get rid of that weak link then the rest will fall into place. Of course there is more to it, I could be wrong, and YMMV.
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Old 18th March 2010, 09:32 AM   #745
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Quote:
Originally Posted by Key View Post
...
So I guess it's my thinking that the speaker which gives the best illusion of the human voice and it's directivity will be the speaker which performs the most consistently.
...
Interesting thought ...

Measurement of 3D Phoneme-Specific Radiation Patterns in Speech and Singing - 2007 Scientific Report

Examination of human voice properties is most interesting, since
there are often analogies between those properties and
our hearing since speech perception is one of the major tasks
of our hearing.

As an example i am convinced that is is advantageous, to keep
XO frequencies out of the "directional bands" found by BLAUERT.
Especially if the directivity has discontinuities around the crossover
frequency of a speaker.

The above exercise shows, that directivity of vowel frequencies
is speaker dependent to some degree - which may lead to
speculation whether those directivity patterns belong to
what we call "speaker identifying features"...

Although i was confronted with speaker specific features during
development of speech recognition systems, i had never
examined those directivity patterns systematically.

But there are patterns to be found even when averaged over many
speakers. Those may truly be worth to take into consideration, when
judging directivity patterns of loudspeakers.

Another circumstance is that spoken and sung vowels e.g. may differ
considerably in spectral distribution and differences in spectral directivity
are to be expected also ...
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Last edited by LineArray; 18th March 2010 at 09:53 AM.
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Old 18th March 2010, 10:00 AM   #746
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As a first common statement we can imagine the human voice to
be a directional sound source, having a mainly kardioid pattern
thereby getting more directional with frequency.

That "human voice sound source" is in a common communicative
situation pointing at the listener with its main direction of radiation.

Trivial, but interesting to keep in mind.
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Last edited by LineArray; 18th March 2010 at 10:08 AM.
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Old 18th March 2010, 10:21 AM   #747
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@graaf:

To give support to your ceiling flooder:

Is it true that an actor on the stage may use the ceiling -
to adress the audience dependent from the acoustical
situation - by directing his voice upwards, at least as an
artistic element ?
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Old 18th March 2010, 10:31 AM   #748
el`Ol is offline el`Ol  Germany
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Quote:
Originally Posted by Cal Weldon View Post


Hmm, let's see, Loudspeakers and room as a system.

Nope, none of the last ten posts had anything to do with the title. Sure was fun weeding through all that useless banter though. I know, why don't you two take a break from this thread. Might do you some good.
To say something about DMLs that belongs to the topic:
According to this paper they have sharper wavefronts than conventional speakers and are more sensitive to room modes.
http://www.essex.ac.uk/csee/research...tion%20DML.pdf
For more about these speakers see this thread:
PIEZO NXT type panel
From post 422 on you find theoretical discussions.
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Old 18th March 2010, 10:56 AM   #749
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Default Speaker-Room Interaction and DML

This paper is unfortunately in german language

http://www.wvier.de/texte/NXT_Tonmeistertagung.pdf

but from pictures 11 ... 12, which show interference effects between
DML and neighboured walls, i would interpret the result in
exactly the opposite direction.

I could not find these exercise in english language, but the
picture from the experimental setting and the resulting plots
should be self explaining to some degree.
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Old 18th March 2010, 11:22 AM   #750
el`Ol is offline el`Ol  Germany
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Sounds much more reasonable, and of course measurements can be trusted more than simulations. Some people who want to have best of both worlds combine directive speakers with DMLs. This can be done without interferences.
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