Loudspeaker perception

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#483
ScottG said:
Of course he could have been proposing something else altogether..😉
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Wish I had time to read this more thoroughly and to respond in more detail, but as Markus has noted, I spend too much time in these forums and I have others things that I need to do.

My particular point of view goes back to some discussions that I once had with Heinrik Kuttruff. If you don't know who he is you must look him up. I have considerable respect for him, just as I do for all the renowned German Acousticians (My advisors were Czech and German). We talked about small rooms and about very early reflections i.e. < 10 ms. He said that he would have to surmise that these would be very detrimental to sound quality. If you look at almost all data for reflections etc. they tend to take a nose dive just below 10 ms. Kuttruff also noted this, but was never that interested because such reflections never occur in his venues.

Being in Car audio I spent a lot of time thinking and studying these <10 ms events and concluded that they were bad things, and yet, just like Toole has noted everything > 10 ms. seems to be positive in almost all circumstances.

This belief drives my designs. I try and get nothing < 10 ms. and as much as possible > 10 ms. A long narrow room with the right directivity does this if the walls are reflective (except behind the front speakers.

Theres lots more to the story, but thats all the time that I have.
 
#484
Scott, I'm not sure if I understood your explanations. Lower IACC of the side wall reflection by crossing the speakers 0° axis in front of the listening position - understood. But those reflections shouldn't arrive too early. Having the speakers on the long wall helps in delaying them. Even reflections arriving from up to 150° can contribute to a higher ASW.
 
#485
Originally posted by gedlee I try and get nothing < 10 ms. and as much as possible > 10 ms. A long narrow room with the right directivity does this if the walls are reflective (except behind the front speakers.
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Earl, you know the data by Devantier that Toole uses all the time: in a typical small room all first reflections arrive within 10 ms.
 
#486
Thats a typical room with wide directivity speakers. In my rooms there is almost nothing from the direct arrival to the first opposite side wall reflection and this is just about 10 ms. - a little less, but you get the picture. Things improved when I got rid of the ceiling and floor reflections which were definately under 10 ms. The Toole data contains those reflections I believe.

It is just this point that I made with Floyd and his answer was not satisfying. He said that people don't seem to mind, but then again they had never experinced anything else either so thats a judgement without any comparison.

I'll do an impulse response in my room sometime - just don't have the time right now to play around with a system that works fine. When I'm in my theater its to enjoy it, not to measure it.
 
#487
#489
Originally posted by gedlee Wish I had time to read this more thoroughly and to respond in more detail, but as Markus has noted, I spend too much time in these forums and I have others things that I need to do.
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And you haven't completed one of the things I ordered you to do either! :whip:

Originally posted by gedlee When I'm in my theater its to enjoy it, not to measure it.
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I think I misunderstood this whole speaker thing completely.
 
#491
which reflections contribute to ASW and which to spaciousness and which to envelopment?

I assume that there is difference between the two - apparent sound width and spaciousness
or perhaps is this assumptions wrong?

what does this diagram mean? what are relationship between spaciousness and image shift/broadening (=ASW?) and envelopment
does "spaciousness" = image shift/source broadening (for 1<8 kHz reflections delayed < 80 ms) plus envelopment (for 150<500 Hz reflections delayed > 80 ms)?

(just two different frequency dependent faces of "spaciousness"?)

does Toole consider "spaciousness" such understood as good and desirable?
"image shift/source broadening" included?
"shift/broadening" has certainly nothing to do with accuracy

but perhaps with realism?

best regards!
graaf
 

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#492
Which end and start at 1kHz. I had this subjective perception that there the overall sense is stronger for reproduced stereo. But I was told that there exactly is where the hearing goofs. Where is the elementary my dear Watson?
 
#496
No, I was talking about Kuttruff's books. "Room Acoustics" is a gem.

Tooles book is interesting, but its not a mathematical treatise on room acoustics like Kuttruff's book. I enjoy reading Floyd's book, but Floyd is not really an engineer in the sense of his expertise at designing anything. He is an evaluator not a designer. One could not design a loudspeaker or a room after reading Floyd's book.
 
#498
I'll have to look back at some sections but if I remember right Toole was showing data that came from an anechoic chamber experiment with two loudspeakers. One was set up to produce direct sound, the second was set up with an angle and delay that mimicked the first side wall reflection. Listeners were given a knob that controlled the level of the "reflected" sound and told to adjust it to where it sounded best. Most preferred to dial in a lot of reflection but I can't remember what range of delays were tested. I can't help but wonder were listeners craving that reflection because the space was otherwise totally deficient in reflections? Would changing to stereo have made a difference? (he notes in the brief discussion of a dipole test that it did much better in stereo than mono when subjectively rated for spatial effects)
 
#499
salas said:
Which end and start at 1kHz. I had this subjective perception that there the overall sense is stronger for reproduced stereo.
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such is also the conclusion of ten years research conducted by Stereolith inventor Mr Walter Schupbach:

In den letzten zehn Jahren habe ich herausgefunden, dass die Stereoinformation hauptsächlich um die 1000 Hz liegt.
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"stereo spatial cues are to be found mainly around 1 kHz"

see interview: http://www.avguide.ch/index.cfm/show/page.view/uuid/392ED1B8-8A11-97B0-44C907EC204BF1BB

therefore he decided to go mono in the highs in his latest designs - crossover frequency between stereo midbasses and mono tweeter is set at 2.8 kHz

salas said:
But I was told that there exactly is where the hearing goofs.
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yes - in case of REAL sound sources when one listens to live sound
not necessarily in case of PHANTOM sound sources when one listens to stereo setup

it seems that REAL and PHANTOM sound soruces are defined by entirely different set of spatial cues

salas said:

Where is the elementary my dear Watson?
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it seems that elementary of spatial hearing of stereo PHANTOM sources has not been written yet

best regards!
graaf
 
#500
I had another look and I had two experiments mixed up. The one I was thinking of actually gave listeners a control for reflection delay at a fixed level and asked for their subjective preference. It doesn't look like values under 10ms were preferred for any level. I'm looking at the figure 7.2 which says it was adapted from Ando 1977.
 
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