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Research on reflections

youngho

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Building absorbers like that, with plates/slats to scatter and reflect sound, gives great flexibility for adjustments. If it is too dead - add more wood, if it is too bright or lively - remove some.

Those designs with different width slats looks great, I have seen them elsewhere, on a yt-channel called "Acoustics insider".
The slats remind me a little of https://www.weslachot.com/project26.html

Young-Ho
 

bo_knows

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The slats remind me a little of https://www.weslachot.com/project26.html

Young-Ho
Thank you for sharing the link. :)
I do not want to derail the topic of this thread but I believe this is all related.
What a studio design. Wow! So the front wall is dead (absorbed), sidewalls are angeled and utilizing the scatter plates with absorption to control the flutter echo and provide some reflections away from the studio engineer's ears, back is diffused to create spaciousness. The ceiling is dead (heavily absorbed) and the floor is "live" (reflective). It looks like they are using Dynaudio M3A monitors with the soft dome tweeter. If they absorb too much mid and high frequencies, I would think that tweeter would start to sound too "mellow" in that space. There's a lot to be learned from this studio design. The room must sound amazing. Due to the way the pictures are taken (distorted via lens), I can't get a real feel for the size of the room but it looks way wider than most domestic rooms. So if they are treating their sidewalls in that manner, it can be that bad. Another take on the same concept (Focal main listening room):
The Source is Stereophile.


1636223328519.png
 
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hemiutut

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Thank you. I would like to think that I'm on a right track. I sit 8.1 feet from the speakers.
There's still more work to be done in my room (currently experimenting with qrd 734 diffusers on sidewalls above the absorbers.) I know they make a nice difference but my listening position allows for only 6 feet of distance from them. They bring a lot of energy that I can feel it in my ears. Strange feeling that almost overwhelms my ears and makes the sound a touch brighter but gives a more feel for the front of the sound stage.
My KEF R500 apparently has narrow dispersion but the first reflection are being absorbed. The sound stage is a big as the recording is calling for. So for me, absorption on the sidewall works fine.

Hello bo_knows
Nice treatment and it sure does a very good job.

index.php

index.php


Do you have measurements made with REW?
Can you put the .mdat file?
Just curious to see the acoustics of the room.
Written with translator.

Greetings
 

CREMA

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Cap.PNG

Cap2.PNG

Whether it's a wide or narrow dispersion, I think the most important thing is a room.

It would be nice to be able to remove very early reflections of less than 5ms, create early reflections of -20dB level around 15-40ms, and have good control over late reflections and reverbs afterwards. (Of course, the characteristics of the loudspeaker will have a key influence on producing such a result.)

It would be better to think carefully about the characteristics of the room and organize the room acoustic and choose the best loudspeaker accordingly.

Or, it's not bad to listen to music with a near-field system focused on direct sound like me. Because there is also an option to expand ASW to DSP...
 

Jack B

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don't know how someone expects to have a good image if when what is supoused to come from the right is copied on the left and vice versa. the nearer wall reflction might be constructive, but the oposite wall reflection is terribly desctructive
Ahh, but how to allow the first side-wall reflections and also absorb the opposite wall reflections? Can it be done?
 

Jack B

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Much progress has been done in later years, what this is about is the acoustic properties of the room and the speaker radiation pattern.

Some interesting points:
- We are doing sound reproduction, not sound production.
- No, early reflections - especially discrete - are not beneficial.
- Effects of vertical and horizontal radiation pattern are different - as some have also described in this thread.
- Increasing indications that one specific radiation pattern is the best - and generally preferred.
- We now know how to fix the room.
Others may disagree (and some do).
 

fineMen

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Ahh, but how to allow the first side-wall reflections and also absorb the opposite wall reflections? Can it be done?

don't know how someone expects to have a good image if when what is supoused to come from the right is copied on the left and vice versa. the nearer wall reflction might be constructive, but the oposite wall reflection is terribly desctructive

The mystery is called "precedence effect" - once the idea were the sound comes from is established in the beautyfull mind of the listener ( I hate to talk about some anonymous "the brain", it's so inhuman ), that idea is kept for longer. Reflective sound is subsummized under that first direct sound. If it is somehow plausible in terms of spectral content and other cues.

Ehm, to elaborate on that a bit more:

In real life, which actually exists, and there is live music in some room, which is possible even with real musicians--one has the opportunity to turn the head a litte, to move a step aside and so forth, that would only confirm (!) the idea of the direction where the sound comes from

In stereo the contrary is true--move or turn head, the virtual "image" is disturbed, maybe destroyed

The latter is not related to the reflections. The stereo illusion is, even with speakers, head related, not room related. It is always about a combination of relative amplitude and time delay at the head of the listener (me for instance) which gives a first and sofar final impression of the localization. And that is kept for some time. The room dependend reflections are within a wide margin of no further effect.

Stereo is fragile, because that first impression cannot be confirmed by biological reflexes, namely moving the head. To the contrary. To train stereo seems to rigidly withstand natural reflexes, maybe?

That simple.
 
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Jack B

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I don't know a helluva lot but am learning. Thus far I am favoring "envelopment" over pinpoint imaging. Listen to mostly classical music (along w. some classic rock) in a fairly small room. BTW, I love the phrase "the infamous soundstage".

Thanks all, for your contributions to the body of knowledge!
 

fineMen

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I don't know a helluva lot but am learning. Thus far I am favoring "envelopment" over pinpoint imaging. Listen to mostly classical music (along w. some classic rock) in a fairly small room. BTW, I love the phrase "the infamous soundstage".

Thanks all, for your contributions to the body of knowledge!
I think it is a cultural thing.

First the reflexes. Most people cannot breath, really, if the inner skin of the nose gets wet. It is inhibited by a reflex from our baby days. Under water, don't catch for air! That for SCUBA divers use masks that cover the nose. But for an emergency situation You should be able to suppress the reflex, which is the first training one gets in that field.

Fragility of stereo. Think of a cinema screen that would shrink, say to half its size left on a head movement of only a few inches to the right. Same in the other direction, move left, and right size of the screen shrinks vastly. Not that funny. That are the proportions with stereo, though. 10 cm lateral shift or a turn by 20°, shrink to the half and warp also.

I'm used to listen actively. That implies such movements easily, and more. I feel tied up when I'm asked to suppress the reflex of listening actively.

Today some population accepts movies on a smart phone screen, accept to listen hard to the newest song over crappy built in speakers--stereo of course.
 
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Jack B

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I think it is a cultural thing.

First the reflexes. Most people cannot breath, really, if the inner skin of the nose gets wet. It is inhibited by a reflex from our baby days. Under water, don't catch for air! That for SCUBA divers use masks that cover the nose. But for an emergency situation You should be able to suppress the reflex, which is the first training one gets in that field.

Fragility of stereo. Think of a cinema screen that would shrink, say to half its size left on a head movement of only a few inches to the right. Same in the other direction, move left, and right size of the screen shrinks vastly. Not that funny. That are the proportions with stereo, though. 10 cm lateral shift or a turn by 20°, shrink to the half and warp also.

I'm used to listen actively. That implies such movements easily, and more. I feel tied up when I'm asked to suppress the reflex of listening actively.

Today some population accepts movies on a smart phone screen, accept to listen hard to the newest song over crappy built in speakers--stereo of course.
Agreed that two-channel stereo is limited and limiting. Been playing with different flavors of enhancement to three or more channels (Dolby, DTS, Auro).

And how can we relate to someone who is watching a 4K movie on a tiny smartphone? The sound and the visual are so compromised that there is almost no reason to bother...worse than nothing at all! "Thus sayeth the Lord!"
 

dasdoing

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Ahh, but how to allow the first side-wall reflections and also absorb the opposite wall reflections? Can it be done?

easy: just put an absorbive panel in the middle. room will look stupid though lol

plus: if you extend it all the way to the listener you also eliminate the cross-talk.


EDIT: alternitavly you could put the panels on the (in)side of the speakers
 

dasdoing

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btw. you could also avoid the unwated reflection by fireing into the wall like this:


a.png


today we have DSP so the FR could be made as good (if not better) as with direct sound+reflections.
 

bigjacko

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If my recollection doesn't trick me, this patent was already granted to BOSE.
Can you even grant patent like this? This is not innovative thing and it can be easily designed from people in that field.
 

Spocko

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you can do crosstalk cancelation with regular speakers using https://en.wikipedia.org/wiki/Ambiophonics
Since it's one of the original applications of DSP that appears to be standard practice in the home theater domain, I'm assuming it is a core element of all AVRs today - if so then the benefit of ambiophonic DSP essentially means we should absorb all early reflections as even a simple 4 speaker array provides its own early reflections and spatial cues. Thanks for the article! I'm now more confident than ever that for home theater purposes where DSP is the core driver of the entire experience, we must treat early reflections since these auditory cues are also provided by the speaker array (unlike "pure direct" stereo listening).
 
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