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Speaker choices for a reflective, large room

RayDunzl

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Electrostats are called bipole speakers because they throw out sounds equally forwards and backwards.

Dipole.

Maybe equal but opposite phase.
 

RayDunzl

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The ML will "project" the sound differently than a wide dispersion speaker.

The panel will be barely louder than the room.

You can put your nose right up to it and it still sounds 3 feet away.
 

Galz

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Why not move the whole seating setup closer to the screen? You'll enjoy your small TV better (and even an 85" would benefit from moving closer), get away from the rear wall, and could maybe even optimize the seating position for best bass. The design aspect doesn't have to end up bad if you are creative enough to find a use for the new space behind the couch.

I'm no expert but I'm guessing the niche for the TV, the glass in the room and the ceiling are acoustical disasters. But if you get nice enough looking speakers you can probably afford (design-wise) to move them into the room and somewhat reduce the effect of that disaster.
 
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HooStat

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Why not move the whole seating setup closer to the screen? You'll enjoy your small TV better (and even an 85" would benefit from moving closer), get away from the rear wall, and could maybe even optimize the seating position for best bass. The design aspect doesn't have to end up bad if you are creative enough to find a use for the new space behind the couch.

I'm no expert but I'm guessing the niche for the TV, the glass in the room and the ceiling are acoustical disasters. But if you get nice enough looking speakers you can probably afford (design-wise) to move them into the room and somewhat reduce the effect of that disaster.
I appreciate the thought. But that is not possible. So, my question is narrowly focused on what type of speakers might be the best in this situation.
 

Pdxwayne

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Are you able to do home trials of some Paradigm offerings? Compared to other center speakers I have used, I like my Paradigm center speakers the best in term of speech clarity. Mine are from Studio and Signature series and already discontinued. But current offerings should behave similar.
 

DVDdoug

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Mostly off-topic, but...

For music I generally like a lively environment, but dialog can be a different issue -

So, the sound needs to be loud because the space is big, which exacerbates the reflections. We don't actually like it loud, but the louder it is, the easier it is to hear the dialog clearly.
The company I work for is slowly expanding and a couple of years ago, a few of us moved into a warehouse-sized space (I don't know the square footage). Hard walls & floor. The ceiling has insulation (fiberglass I assume) with the paper-side exposed. There was so much reverb that it was hard to converse if you were more than about 3-feet away... A very strange "feeling"! Now it's more than half-full of desks & workbenches and "stuff" an the acoustics are a lot more "normal".

...And I just remembered a church I used to go to where there was so much reverb you could hardly understand the preacher. They had distributed speakers along the walls. Some time later they took those out and put-in one-big speaker high in ceiling in the front. Surprisingly (to me) that made it 100% better. They didn't do any acoustic treatment.
 

NTK

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Let me start with a few imo relevant points made by acoustics and psychoacoustics researcher David Griesinger:

"The goal of the ear/brain is to extract meaningful sound objects from a confusing acoustic field. To the brain reverberation is a form of noise. Where possible the brain stem separates direct sound from reverberation, forming two distinct sound streams: foreground and background."

“If you want to communicate with sound, you need to make the direct sound distinctly audible.”

"The earlier a reflection arrives the more it contributes to masking the direct sound."

"Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough." (Ten milliseconds of reflection-free time is long enough for the ear to separate the direct from the reflected sound down to 700 Hz, according to Earl Geddes.)

Imo the above quotes point towards maximizing the direct-to-reverberant sound ratio, which implies narrow-pattern speakers. The next (long) quote will indicate that frequencies north of 500 Hz are the most important for speech, which implies that a narrow (and ideally uniform) radiation pattern down to 500 Hz would be great, but that below 500 Hz the radiation pattern doesn't matter as much:

"It is well known that the information content of speech is (almost) entirely in frequencies above 500Hz. For all people, even children, this means that information – at least the identity of vowels – is encoded in amplitude modulations of harmonics of a lower frequency tone... harmonics have a unique property – they combine to make sharp peaks in the acoustic pressure at the frequency of the fundamental frequency that created them... The sharp peaks also facilitate separating the signals from noise, and with the appropriate neural network the peaks from one sound source can be separated from another.

"These peaks only exist when the incoming signal consists of a tone with a definite pitch and lots of upper harmonics. Furthermore, the peaks only exist when there are two or more harmonics at the same time within one critical band." [emphasis Duke's]

The part that I bolded above, about the peaks which exist when the harmonics arrive at the same time, imo implies that a speaker which is time-coherent north of 500 Hz or so is likely to be superior from an intelligibility standpoint. (Floyd Toole did not find phase coherence [and therefore presumably time coherence, which is much more elusive] to contribute to sound quality, therefore my interpretation of Griesinger here is apparently at odds with Toole's position.)

So imo here are four characteristics we'd like:

1. High direct-to-reverberant sound ratio at the listening positions;

2. Minimal reflections arriving within the first 10 milliseconds (Toole and Griesinger both consider reflections in the vertical plane to be relatively benign, so this is mostly about lateral reflections);

3. The reflections should have approximately the same spectral balance as the first-arrival sound; and

4. Time coherence north of 500 Hz is arguably desirable.

Imo the Dutch & Dutch 8c and JBL M2 are two strong candidates (even if you have early reflections off the wall behind you). But I wanted to post the Griesinger quotes because they offer a basis for evaluating these and other candidate loudspeakers. A speaker with a bit narrower pattern than either, perhaps in a two-way with a bit lower crossover point than either, might also be a candidate, IF it is as free from colorations and limitations as the 8c and M2.
I was reading this paper by Dr @David Griesinger just a few days ago.
http://www.davidgriesinger.com/paris.pdf

He talked about the fluctuations in the interaural time delays (ITD) and interaural intensity differences (IID) giving us our sense of space in the reproduced sound.

Griesinger1.PNG


He also talked about the techniques recording and mixing engineers need to employ. I believe what he said applies to speakers and room acoustics too. Our speakers and rooms should properly reproduce these recorded reflections/reverberations (if they are actually in the recordings), not too little and not over-emphasized.

Griesinger2.PNG
 

Duke

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I was reading this paper by Dr @David Griesinger just a few days ago.

http://www.davidgriesinger.com/paris.pdf...

He also talked about the techniques recording and mixing engineers need to employ. I believe what he said applies to speakers and room acoustics too. Our speakers and rooms should properly reproduce these recorded reflections/reverberations (if they are actually in the recordings), not too little and not over-emphasized. [over-emphasis Duke's]


Well said!

My understanding (from comments made by Floyd Toole and others) is that the sadly long-discontinued Lexicon processor David Griesinger invented is the best such unit ever made. Probably because Griesinger started out with the most nuanced understanding of "where the goal posts are" and "how to get there".

Griesinger on the subject of subject of "envelopment":

"Envelopment is the Holy Grail of concert hall design. When reproducing sound in small spaces [home listening rooms], envelopment is often absent. Envelopment is perceived when the ear and brain can detect TWO separate streams: A foreground stream of direct sound. And a background stream of reverberation. Both streams must be present if sound is perceived as enveloping."

"Where the background stream is easily separated from the foreground stream, envelopment is about 6 dB stronger for a given direct-to-reverberant ratio."

Our home audio listening rooms will never begin to have the acoustics of a concert hall because our reflection path lengths are inevitably much shorter, so the solution advocated by @Floyd Toole and @Kal Rubinson and others is upmixing and/or using multichannel recordings. But I think there is still hope for two channel:

Given a good recording, the desired venue acoustic signature (whether real or engineered or both) is already ON the recording. So one solution would be to effectively present the acoustic signature already on the recording while simultaneously minimizing the "small room signature" of the playback room. This implies an alternative paradigm, where the in-room reflections are seen as the carriers of the venue cues on the recording. Imo good results are possible, but I do concede that multichannel is still a more generally effective way to get envelopment.

@HooStat did not mention envelopment as being one of the things he's looking for, but if so, imo his large and unusually reflective room may be a better candidate for extracting the most venue information reasonably possible from two speakers, rather than adding more reflections via multichannel.
 
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Kvalsvoll

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2. Wide dispersion stereo speakers like Revel 328Be (or similarly wide dispersion speakers). The thinking is that if the reflections are uniform, it will be easier to hear.

Others have already given quite elaborate input on this, I am going to try to explain as simple as possible, why the above is wrong.

Think of the sound from the room as noise, that obscures the sound from the speaker - it is the direct, early sound form the speaker that carries the information needed to understand dialogue, and all other sound - including reverberated sound from the room - is simply noise. When all that noise becomes too loud, it will be difficult to hear the sound that comes directly from the speaker.

To improve this situation, it is necessary to increase the early-to-late sound ratio. This can partially be done by changing the sound source - the speaker - or, by changing room acoustic properties.

In most such real-world cases, it is not possible to change room acoustics to a level that fixes the problem - regardless of budget, knowledge - simply because the effort needed far exceeds the purpose - you just want to be able to hear the dialogue.

Sitting closer to the speakers also helps, but in most cases location of both speakers and listeners are fixed due to how you want to place things in the room - for practical and aesthetic reasons.

Then you are left with changing speakers. This can improve things sufficiently so it is possible to get acceptable intelligibility, also at reduced volume.

The best solution is to install a center speaker above the screen, and this center speaker must have a controlled radiation pattern - sound must be directed towards the listeners, and all sound outside this area must be attenuated. This speaker should have a reasonably flat frequency response across the area where listeners are located.
 

Kvalsvoll

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Let me start with a few imo relevant points made by acoustics and psychoacoustics researcher David Griesinger:

"The goal of the ear/brain is to extract meaningful sound objects from a confusing acoustic field. To the brain reverberation is a form of noise. Where possible the brain stem separates direct sound from reverberation, forming two distinct sound streams: foreground and background."

“If you want to communicate with sound, you need to make the direct sound distinctly audible.”

"The earlier a reflection arrives the more it contributes to masking the direct sound."

"Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough." (Ten milliseconds of reflection-free time is long enough for the ear to separate the direct from the reflected sound down to 700 Hz, according to Earl Geddes.)

Imo the above quotes point towards maximizing the direct-to-reverberant sound ratio, which implies narrow-pattern speakers. The next (long) quote will indicate that frequencies north of 500 Hz are the most important for speech, which implies that a narrow (and ideally uniform) radiation pattern down to 500 Hz would be great, but that below 500 Hz the radiation pattern doesn't matter as much:

"It is well known that the information content of speech is (almost) entirely in frequencies above 500Hz. For all people, even children, this means that information – at least the identity of vowels – is encoded in amplitude modulations of harmonics of a lower frequency tone... harmonics have a unique property – they combine to make sharp peaks in the acoustic pressure at the frequency of the fundamental frequency that created them... The sharp peaks also facilitate separating the signals from noise, and with the appropriate neural network the peaks from one sound source can be separated from another.

"These peaks only exist when the incoming signal consists of a tone with a definite pitch and lots of upper harmonics. Furthermore, the peaks only exist when there are two or more harmonics at the same time within one critical band." [emphasis Duke's]

The part that I bolded above, about the peaks which exist when the harmonics arrive at the same time, imo implies that a speaker which is time-coherent north of 500 Hz or so is likely to be superior from an intelligibility standpoint. (Floyd Toole did not find phase coherence [and therefore presumably time coherence, which is much more elusive] to contribute to sound quality, therefore my interpretation of Griesinger here is apparently at odds with Toole's position.)

So imo here are four characteristics we'd like:

1. High direct-to-reverberant sound ratio at the listening positions;

2. Minimal reflections arriving within the first 10 milliseconds (Toole and Griesinger both consider reflections in the vertical plane to be relatively benign, so this is mostly about lateral reflections);

3. The reflections should have approximately the same spectral balance as the first-arrival sound; and

4. Time coherence north of 500 Hz is arguably desirable.

Imo the Dutch & Dutch 8c and JBL M2 are two strong candidates (even if you have early reflections off the wall behind you). But I wanted to post the Griesinger quotes because they offer a basis for evaluating these and other candidate loudspeakers. A speaker with a bit narrower pattern than either, perhaps in a two-way with a bit lower crossover point than either, might also be a candidate, IF it is as free from colorations and limitations as the 8c and M2.

This post explains speech intelligiblity issues in different words, and more extensive. I find it quite good.
 

fineMen

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Thank you. That seems clear now. I appreciate your help, and that of others including @Duke in clarifying this for me.
We just had a brief argument regarding the merits of ->early (lateral) reflections. These are missing in Your room, aren't they? All reflections, except from behind the sofa, are late by any standard. Regarding more directional speakers, like Double Dutch, they stand out not so much because of more directivity. The cardioid technique shifts down the frequency, at which directivity starts to increase, that's all. It wouldn't help to much then. I can't imagine to use pro speakers in that room. Such would really provide a beaming directivity. If that helps, I doubt it.

What about additional speakers close to the sofa? I don't want to go into details, but they could do two things.
- decrease the relative amplitude of (very) late reflections, vulgo 'echoes'
- make the room appear smaller to the hearing

I would try as follows: not to small extra speakers left / right, fed with a delayed signal, with an amplitude found by experimentation. First guess for the delay would be such that the sound from the extras would arrive just 2..10ms later than the sound from the main speakers upfront.

Edit: 'have seen that early reflections were mentioned here before. I would go for it. They are explicitly not "just noise".
Another one: the speakers I see depicted in the foto are way to weak. Maybe the problem originates in a rapid decline of general sound quality once the output volume reaches sufficient levels for that room. Speakers behave differently, but this is way to small, whatever technique it comprises. You may want to just try reasonably potent speakers, without any fancy tech for starters.
 
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abdo123

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Personally i would get a custom-built line-array. 'Regular' speakers have too many problems once they're placed anything but the center of the room.

1635928487479.png
 

Willem

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Our large listening room too has a lot of glass windows, hard (brick) walls and a hard floor (with a rug), plus some bookcases. The acoustics is hard, but the Quad 2805 electrostats (with subs) sound fine, and dialogue is perfectly clear. Closing the curtains makes a pleasant difference with respect to conversation with guests, but not really when listening to the speakers.
 
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