Meaning, that Pluto's are only fit for nearfield listening? They strike me as an excellent way of getting the job done, at any distance ...
Overall, I see audiophiles listening to systems in 2 ways: they are either hunched over in the sweet spot, shoulders almost on top of the system; or sitting way, way, way back in an enormous room, the speakers are lost in the mists at the other end,
...
I reckon there are other ways of doing it as well ...
Frank
Overall, I see audiophiles listening to systems in 2 ways: they are either hunched over in the sweet spot, shoulders almost on top of the system; or sitting way, way, way back in an enormous room, the speakers are lost in the mists at the other end,
...I reckon there are other ways of doing it as well ...
Frank
I think you can get far enough there.. try measuring it.
Huh? You're the guy making the dubious claim....
I think you need to go back and read my post again:
http://www.diyaudio.com/forums/mult...ns-beaten-behringer-what-233.html#post3428971
Under the conditions mentioned, you can have a lower range than 700 Hz. You don't have to use sounds that have harmonics that "trail-up" higher than 700 Hz with any significant intensity. Humming doesn't have the same character as speech (or specialized singing) as mentioned in the formant web page you linked to. No does it have an onset quality (if sustained).
You can always use an rta (there are freeware versions), to get the right humming "note" that meets the general "less than 700 Hz" condition if you feel the test isn't rigorous enough. If the humming sound results in a sound above 700 Hz with any significant intensity - have the person hum lower.
It really isn't that difficult a concept.
I did read them and I'm very curious what his reply to your email will be
Interesting quote for Barleywater:
"Toole and Olive [5] studied the audibility of individual re-flections in rooms, and in [6] Toole implies that if individual reflections are below the level of audibility with respect to the direct sound they can be ignored. This is clearly not the case. In small rooms individual reflections are almost always inaudible individually, but there are a great many of them, and their sum is highly audible."
http://www.davidgriesinger.com/ica2010/paper2.doc
I did read them and I'm very curious what his reply to your email will be
Interesting quote for Barleywater:
"Toole and Olive [5] studied the audibility of individual re-flections in rooms, and in [6] Toole implies that if individual reflections are below the level of audibility with respect to the direct sound they can be ignored. This is clearly not the case. In small rooms individual reflections are almost always inaudible individually, but there are a great many of them, and their sum is highly audible."
http://www.davidgriesinger.com/ica2010/paper2.doc
Continuing that quote:
"The energy in the reflections in halls is greater than the energy in the direct sound for an obvious reason: the strength of the direct sound decreases 6dB with every doubling of distance from the source. In a typical concert hall half the seats have a D/R less than -10dB. In almost all seats the D/R is less than -3dB. A major purpose of a hall – besides keeping out the rain – is to capture sound that does not travel directly to a listener, and re-direct it to the listeners. In the best halls the re-directed sound increases loudness without compromising engagement."
Yes, if listening to stereo in conditions Griesinger describes, localizing direct sound becomes difficult.
If speakers and room are set up to get D/R this poor, then room is being listened to and not speakers. This situation is exacerbated with high directivity speakers that fall off less than -6dB per doubling in distance.
Couple this with tendency to set speakers in plane of short walls in shoebox shaped rooms, and listening as far back as possible. This insures back wall reflection has greatest impact possible on direct sound.
This is broken listening room for stereo (or any listening IMHO), and is easily fixed.
Griesinger is highly satisfied with binaural recordings he makes as most consistent tool for A/B differences in listening locations.
He also states: "They also play back reasonably well through loudspeakers in a non-reverberant room." I take this to mean that differences in seats at listening halls provide binaural cues that translate well enough to loudspeakers for Griesinger to make judgments of "engagement" and "muddiness". These cues appear most effective >700Hz, and less than 5kHz for otherwise broadband signals. Ear canal is transmission line with single mode of vibration for signals in these ranges.
It is very easy to synthesize and demonstrate binaural recordings that show dominance of timing over amplitude for localization of 700Hz-5kHz based broadband signals. This requires hearing mechanism that effectively determines absolute phase between otherwise identical impulse responses.
Polar response of a speaker that change timing cues reaching each ear result in spatial distortion. This is most apparent when two such speakers are used for phantom image generation.
This is incorrect - they fall at the same rate as any other speaker, the sound field is are just more directed, which makes their D/R higher just as Griesinger is looking for - fewer very early reflections above 700 Hz.
Now you are getting into the grey area! We know that the first few ms of hearing create the perception of image and reflections and/or diffractions in this time period can only degrade this image. A few ms of clean response is not impossible, but many people ignore the diffraction problem. Objects near the speakers and the speakers themselves can create sound impulse in these first few ms. I have found that extreme attention to this pays big dividends in terms of image.
Then comes the first early reflections. In a small room these are impossible to remove completely, but here is what I use as a guide: 1) the later they arrive the better - this is where directivity comes into play because only directivity can enhance the gap between the direct and the first few reflections. This is most important above 700 Hz, just as Griesinger says. 2) first reflections from a right signal to the opposite ear are less of a problem that a first reflection to the same ear. If the left and right signal are uncorrelated then the opposite ear situation adds two uncorrelated signals and the ear can partially sort this out, but if the direct and first reflection are correlated then the sum is complex (a kind of comb filter) and the ear has no means to sort out the uncontaminated signal from the sum. In all cases, lower levels of reflections are better in the first 10 ms. After about 10 ms I would claim that all lateral reflections are good, although Griesinger would like to see 100 ms. But 100 ms is impossible in a small room and this is where I would love to discuss with him how one would modify what he has done to a small room situation.
Also of particular note in the Greisinger papers is his claim that reflections in the vertical plane as simply ignored by our hearing. This position seems extreme, but I have always believed that vertical reflections as less of an issue that horizontal ones.
So, in a nutshell, that is how I see the situation.
Then comes the first early reflections. In a small room these are impossible to remove completely, but here is what I use as a guide: 1) the later they arrive the better - this is where directivity comes into play because only directivity can enhance the gap between the direct and the first few reflections. This is most important above 700 Hz, just as Griesinger says. 2) first reflections from a right signal to the opposite ear are less of a problem that a first reflection to the same ear. If the left and right signal are uncorrelated then the opposite ear situation adds two uncorrelated signals and the ear can partially sort this out, but if the direct and first reflection are correlated then the sum is complex (a kind of comb filter) and the ear has no means to sort out the uncontaminated signal from the sum. In all cases, lower levels of reflections are better in the first 10 ms. After about 10 ms I would claim that all lateral reflections are good, although Griesinger would like to see 100 ms. But 100 ms is impossible in a small room and this is where I would love to discuss with him how one would modify what he has done to a small room situation.
Also of particular note in the Greisinger papers is his claim that reflections in the vertical plane as simply ignored by our hearing. This position seems extreme, but I have always believed that vertical reflections as less of an issue that horizontal ones.
So, in a nutshell, that is how I see the situation.
He probably says something like this, "Hall shape does not scale. Our ability to perceive the direct sound – and thus localization, engagement, and envelopment - depends on the direct to reverberant ratio (D/R), and on the rate that reverberation builds up with time. Both D/R and the rate of build-up change as the hall size scales – but human hearing (and the properties of music) do not change. Reduc-ing the scale of a hall by a factor of two will only be success-ful if the pitch and tempo of the music increases a factor of two, and the speed of our neurology also increases a factor of two. This does not happen!"
It would seem that we could use multiple approaches to this problem. Attenuation of the first direct reflections may be part of the answer but will be limited to what bandwidth we can attenuate. Then there is also dispersion of the reflection with diffraction panels to break up reflection into lessor coherent bands.
Yes, I read that, but it is not much help. What I would be most interested in is how he would modify, if at all, his LOC calculations for a small room. There are assumptions in those calculations about the arrival times of the direct wave and the early reflections that I don't believe would hold up for a small room.
What I found so interesting in the Greisinger papers is not his work on music venues - they are all much too large for my interest - but on his revised theory of hearing. This theory is revolutionary and explains so much that I was wrestling with in discussions of image perception. Beyond that, the work was interesting, but not all that appplicable.
He must not be interested in small rooms because he has not replied. Usually replies, if they come at all, come quickly.
ok, but how low do they have to be? -10, 20, 30db? The acoustic treatment goes exponential!
seems like even 100ms is low for Griesinger!
http://www.lares-lexicon.com/pdfs/spac4.pdf
the thing is.. you quote him and use him as a reference, but.. so does Linkwitz!
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Room treatments are an option, but heavy damping is not the answer. This will kill more than just the first reflections, it kills them all. High directivity minimizes the first reflections, even in a reverberant room, while the reverberant room extends the later reflections. Diffusers may do that, but absorption won't.
I think that "how low do they have to be" is the wrong question. "Lower is better" is all that I can say. There is no other data on this point.
But only as long as you don't perform the extreme-toe-in-stunt. This creates a high level contralateral reflection.
hi
okay so the first way to help with that is too toe-in the speakers so they cross right in front of your listening position? so that is mandatory?
We don't have a good answer, so it's the wrong question? I think it's exactly the right question. I'd even add a couple more parameters besides level, namely angle, delay, spectrum, number.
Earl,
I didn't say heavy damping, but some damping of first reflection. Couldn't this be done on a limited basis, a thinner damping material working more in the mid to upper frequency range? I can't say I am a room acoustician but I know some people put damping on the walls that is centered on the side wall reflection leading to the seating position. Or would you just be better off using dispersion in that position?
I didn't say heavy damping, but some damping of first reflection. Couldn't this be done on a limited basis, a thinner damping material working more in the mid to upper frequency range? I can't say I am a room acoustician but I know some people put damping on the walls that is centered on the side wall reflection leading to the seating position. Or would you just be better off using dispersion in that position?
I consider the contra-lateral reflection to be a lessor problem that the direct one - it is more delayed, lower level and not a coherent signal.