How NOT to set up speakers and room treatment ( Goldensound)

[thecheapseats]

...Nope. I don't perceive them as echoes at all. I see what we are discussing as simply later reflections that fall within well studied masking and integration time windows....

rhetorically and respectfully - given that first reflections @ 20-30 ms v.s. echos @ 60 ms - exactly how much energy was lost during appx 30 ms while that echo was bouncing around until it got to your ears? (that's rhetorical)... well, your brain knows how much - because it simply isn't as loud (that's not rhetorical)...

edit: oops, had too many zeros...

 

[gnarly]

You can't sit there and keep telling yourself that a dead room is better when you prefer otherwise.

I'm not telling myself anything......in fact, I'm doing the complete opposite by flushing everything I've been told/read about audio down the crapper....
....and simply listening for myself, to speakers outdoors vs indoors.
It's not close when it comes to adding clarity and speech intelligibility.

Have you done that, compare to outdoors? With a system capable of the necessary SPL and bass extension?

 

[TheZebraKilledDarwin]

The above was NOT from Dr. Toole. He was quoting a researcher from BBC. They were opining as to significance of different listening rooms and finding that the impact is minimal. Dr. Toole correctly makes the point that large concert halls are nothing but reverberations. If reverberations are so bad, then why do people like live concerts so much???

Every time I go to a live concert, I listen to see if I can hear "pin point imaging" and it is never remotely there. Everything is diffused. That is what reflections do.

The only live concerts that sound good, are orchestras, because the concert hall is part of the sound and always has been.
I hate live concerts with any kind f amplification, because they sound absolutely horrible. Every studio album is not only sounding worlds better, but the musical performances are much better, too. And you even can hear the instruments...

But according to Mr. Toole, that's not what people want to hear, and you go to a concert too, for the reverberated mess...

 

[dweeeeb2]

Just a thought… could we like concert halls because they look great?

 

[SIY]

The only live concerts that sound good, are orchestras, because the concert hall is part of the sound and always has been.

You need to get out more.

 

[Axo1989]

Because you can't snap your fingers and turn your room into an anechoic chamber. And even if you did, it would sound awful.

Fact is that spaciousness is captivating to audiences. It is what they want and up to a limit, the more the better. I was at a live session at an audio show a few weeks ago organized by a boutique label. The performance finished and I asked the singer if she liked the "dry" version we heard there, or the "sweetened" one that is on the recording of it released. She got all excited and said dry! And went on to say she couldn't believe audiophiles liked it with reverberations. I asked the producer what she thought and she said she added reverb because that is what people like to hear. A quick poll in the room showed everyone agreeing with her.

Why do we like it that way? Because we associate that with realism. From the book above:

"The most neutral sound reproduction is usually not the goal of sound reproduction except in the control rooms of sound recording studios. In homes, both for music appreciation and home movie theater, the goal for many listeners is rather suspension of disbelief a term used in presence research.

Kleiner, Mendel; Tichy, Jiri. Acoustics of Small Rooms (p. 275). CRC Press. Kindle Edition. "

You can't sit there and keep telling yourself that a dead room is better when you prefer otherwise.

The black-and-white "anechoic chamber/dead room" talking point is a furphy, but the argument is making some sort of sense. We are talking about sweet/salty cheeseburgers, warm gooey-centred choc-chip cookies straight from the oven. Or a fabulous roast dinner. Music as comfort food, with dialed-up sentiment and/or spectacle. Totally enjoyable en masse.

Every time I go to a live concert, I listen to see if I can hear "pin point imaging" and it is never remotely there. Everything is diffused. That is what reflections do.

But listen to music always sounding like that at home? I'd think someone had broken my sound system.

 

[Axo1989]

The only live concerts that sound good, are orchestras, because the concert hall is part of the sound and always has been.
I hate live concerts with any kind f amplification, because they sound absolutely horrible. Every studio album is not only sounding worlds better, but the musical performances are much better, too. And you even can hear the instruments...

Yeah I'm not a fan of listening to live albums generally for those reasons. I've been to live gigs where the sound was surprisingly good though. In spaces that shouldn't have worked, using ceiling-mounted line arrays. PA has come a ways I reckon. Not holographic of course, but clear, well-defined and enjoyably loud.

 

[ExPerfectionist]

The question of dialog clarity and intelligibility with / without reflections reminds me of movie theaters. I watched Guardians of the Galaxy 3 a few weeks ago, and was thinking about how incredibly LOUD it was, but dialog and everything was absolutely clear, and the only sounds heard seemed to be directly from the speakers. And it didn't "feel" loud because the sound was clean and I assume very low distortion, very low reverb, very flat frequency response. Good theaters are very well acoustically treated. Poor acoustics in a theater, where you hear both the speakers and the echos, take you out of the movie experience and remind you that you're in a theater. Normal people usually can't turn their home theaters up that loud (dialog and things besides subwoofers and bass) because it feels louder.

Yes, people like music to be loud and enveloping and emotional. And at concerts when musicians try to talk on stage it's often unintelligible unless you're close enough in one of the sweet spots and can hear what they're saying and not the echos or bad acoustics (for anything but loud music).

 

[Guermantes]

Another data point: the 7th edition of Master Handbook of Acoustics by Everest & Pohlmann. There are three relevant chapters, 20, 21 and 24 which deal with domestic listening/home theatre rooms, home studios and professional control rooms respectively.

Chapter 20: Listening rooms

"Reflections from side walls will provide a wide front sound stage, while absorbers on the side walls will provide a more focused sound stage. Diffusion in the back of the room will add spaciousness and envelopment. It is generally best to balance these attributes. A good approach is to selectively add treatment a little at a time while listening to the effect of each addition. It is best to use any one treatment moderately; it is possible to overly treat a room." (p. 438)

They don't assume the domestic listener to be able to do measurements beyond room dimensions in order to ascertain modes but suggest subjective evaluation for reflections. Some of their recommendations are drawn from Olive and Toole's research (among others). Essentially all reflections need to be below a particular threshold relative to the direct sound, otherwise they will cause problems with imaging. In the figure below, F=floor reflection, E=diffraction (rear wall), C=ceiling, S1 and S2 are side walls and curve B is the threshold below direct sound. Yes, the research mentions speech, but they seem to consider speech intelligibility as an important attribute in a home cinema room. On music: "If the taste of the audiophile is highly specialised, the listening-room characteristics can be designed for relatively optimum results for one type of music. If the listener's taste is more universal, the acoustical treatment of the listening room may require compromises to make it suitable for different types of music." (p. 414)

On lateral reflections: "When all of the reflections points are covered, as shown in Fig. 20-7, imaging will probably be much clearer and more precise now that the early reflections have been reduced." (p. 426) But they go on to talk about lateral reflections as something to be tailored to preference.

Chapters 21 and 24 on home and professional controls rooms argue for greater control of reflections, even lateral, and either LEDE or RFZ designs.

 

[amirm]

Chapters 21 and 24 on home and professional controls rooms argue for greater control of reflections, even lateral, and either LEDE or RFZ designs.

There is no evidence that any of those methods were any good. What evidence exists points to speakers with lousy off-axis response, leading people to stuff the side-walls, or front of the room as to lower the impact of those. It is entire old school thinking.

 

[amirm]

But listen to music always sounding like that at home? I'd think someone had broken my sound system.

Not me. I have put great sounding speakers in empty spaces with very high RT60 times with my jaw dropping on how good the experience was. Yes, for pop and rock music the effect was too much but for orchestral, big band, live recordings, etc. was wonderful. On the contrary, when we had a showroom years back at Madrona, we had KEF lend us their Blade speakers. We placed them in our multi-channel theater which was on the dead side. I listened to them and I thought they sounded terrible there. An hour later the KEF folks arrived and they too were very unhappy with the sound as well. So we pulled them out and put them in our open showroom space where they sounded much better.

 

[amirm]

But according to Mr. Toole, that's not what people want to hear, and you go to a concert too, for the reverberated mess...

What? Many people's dream is to recreate that live concert experience. Yet the same people read stuff online and turn their listening rooms into padded cells and wonder why it doesn't sound that way. Sadly their solution is to go buy another power cable....

 

[Axo1989]

But listen to music always sounding like that at home? I'd think someone had broken my sound system.

Not me. I have put great sounding speakers in empty spaces with very high RT60 times with my jaw dropping on how good the experience was. Yes, for pop and rock music the effect was too much but for orchestral, big band, live recordings, etc. was wonderful. ...

Emphasis on always. To some extent we are talking about selecting gear and set-up for different musical tastes. I have some rock-adjacent favourites that absolutely benefit from the big, more reverberant sound as well, it just isn't my main squeeze. I'm interested in experimenting a bit with more adjustable treatments, when I get the time (and fwiw). If that turns out to be interesting, I'll likely post about it.

 

[amirm]

I'm interested in experimenting a bit with adjustable treatments, fwiw.

RPG used to have these "trifuser" products that you would rotate and switch between reflective, absorptive and diffused. We built our entire listening room at Microsoft that way. They were very expensive though and were discontinued a long time ago. This is what they looked like:

The diffusion part was not that good though due to how shallow the wells were.

 

[Guermantes]

There is no evidence that any of those methods were any good. What evidence exists points to speakers with lousy off-axis response, leading people to stuff the side-walls, or front of the room as to lower the impact of those. It is entire old school thinking.

Well the designs are based on research by Davis and Davis, and Berger and D'Antonio, but true we are going back over 40 years. I work in an RFZ design room which is subjectively preferable to the previous rooms I worked in: (1) absorb everything we can afford to; and (2) absorb/diffuse nothing (I used headphones a lot in that room). The RFZ design along with soffit-mounted Genelec monitors is not at all fatiguing to work in over long periods.

 

[Axo1989]

RPG used to have these "trifuser" products that you would rotate and switch between reflective, absorptive and diffused. We built our entire listening room at Microsoft that way. They were very expensive though and were discontinued a long time ago. This is what they looked like:

The diffusion part was not that good though due to how shallow the wells were.

Interesting concept though! I'm thinking more of different side-pieces that slide along the side walls so they can effect first-reflection, or not. I already have a Japanese sliding wall thing going, so an elaboration of that. I'll have to check but someone here mentioned very simple curves that reflect and disperse, and maintain phase coherence. And so on.

 

[youngho]

This reminds me the paper, Vision and Technique behind the New Studios and Listening Rooms of the Fraunhofer IIS Audio Laboratory (inventors of MP3 codec) where they find a floor reflection, put a thick absorber there, only to find it sound wrong and taking it out:

"Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative – unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this. Future investigation will cover the usefulness of this part of the ITU recommendation. The typical listening situation is presented in Figure 12."

What led to them doing this was precisely what our youtuber prescribed:

See what you have to go through to properly learn this topic? Folks still want to insist that you can wake up one morning after reading internet posts and create a video telling people how it is done???

@amirm , thank you, this was an interesting report. I'd just want to point out a few things: "[The floor reflection] can however be attenuated to a negligible level with little effort by placing a piece of moderately absorbing material (e.g. 50 mm thick porous material, about 1.5 m x 1 m) on the floor at the mirror point, i.e. the point, where the sound is reflected on the floor. The measurement result for this case is presented with the red graph in Figure 11." Is 50 mm porous material truly considered to be a thick absorber? Toole has stated otherwise. Also, I was amused by the hand clapping in "The room has been subjectively assessed by several audio experts by listening to various stereo and multichannel sound material and by listening to hand clapping and natural voice sounds." The typical frequency range affected by floor bounce is not likely to be well-addressed by 2" porous absorption.

On the other hand, many "normal" rooms do have carpets or rugs, and Toole himself has advocated for the use of thick carpets with thick wool underlay (page 505 of second edition of Sound Reproduction, listing practical suggestions for room treatment:

"The basic requirements can be summarized as follows:
■ The floor is covered with wall-to-wall clipped-pile carpet on 40 oz/sq yd felt underlay.
■ The center portions of the front and rear walls are mostly absorbing, with scattering devices toward the sides of the rear wall. All absorbers, wherever they are located, must be not less than 3 to 4 in. deep.
■ The side walls are a mixture of reflection, absorption and scattering/diffusing devices.
...
■ Absorbing material and blank reflecting areas should be arranged so that walls facing each other do not present opportunities for flutter echoes (in the drawing facing walls A and D and B and C are designed with staggered areas of absorption and reflection). The total amount of absorbing material in the room must be sufficient to meet the reverberation time criterion discussed in Section 22.3.4.
etc"

Every time I go to a live concert, I listen to see if I can hear "pin point imaging" and it is never remotely there. Everything is diffused. That is what reflections do.

From my recent experience at Boston Symphony Hall, I agree about the lack of pinpoint imaging, but it's also a drastic overstatement to say that that "everything is diffused." Reflections affect the perception of sound sources, but the delay, direction, and amplitude, as well as phase, are all important variables in terms of the magnitude of effects. In terms of classical music venues, here is perhaps a more illuminating exploration of the topic:
https://research.aalto.fi/files/75640242/SCI_Lokki_Auditory_spatial_impression_in_concert_halls.pdf

Along these lines, I think a more meaningful discussion on this entire topic would incorporate the consideration of individual preference, as I outlined a few days ago in point #2 here: https://www.audiosciencereview.com/...atment-goldensound.45104/page-10#post-1608481 (also, it's a little ironic to me that a lot of strenuous disagreement seemed to occur when the final point of the quoted paper seemed to be that it didn't really end up mattering in the long run in terms of performance on the assigned task).

Young-Ho

 

[youngho]

The above was NOT from Dr. Toole. He was quoting a researcher from BBC. They were opining as to significance of different listening rooms and finding that the impact is minimal. Dr. Toole correctly makes the point that large concert halls are nothing but reverberations. If reverberations are so bad, then why do people like live concerts so much???

@amirm, can you please provide a direct quote regarding his opinion on large concert halls being "nothing but reverberations?" I believe that this is a significant overstatement or simplification.

From second edition of Sound Reproduction:
"Toward the rear of a concert hall, the direct sound (the “pure” music) is not the primary acoustic event."
"Once past the first few rows in a concert hall, most of what one hears is reflected sound."
"As a result, classic concert hall acoustical theory often begins with the simplifying assumption that the sound field throughout a large relatively reverberant space is diffuse. In technical terms that means it is homogeneous (the same everywhere in the space) and isotropic (with sound energy arriving at every point equally from all directions). That theoretical ideal is never achieved because of sound absorption at the boundaries, by the audience, and in the air, but it is an acceptable starting point" (emphasis mine)
"In addition, individual voices and instruments do not obey the simplifying assumption of omnidirectionality, so the sound field at different listening positions will be different for different instruments (Meyer, 1993; Otondo et al., 2002). Figure 4.4 shows what happens when the directivity of the sound source is increased in the direction of the listener: The critical distance increases. We hear this at symphonic concerts in the contrast between the penetrating clarity of brasses that deliver a higher proportion of direct sound compared to the open and airy strings that radiate their collective energy more widely."
"The challenge is to put more of the audience in a predominantly direct sound field, precisely the opposite of a live concert hall experience."

I perceive a lot more nuance than "nothing but reverberations." In my last post (https://www.audiosciencereview.com/...atment-goldensound.45104/page-26#post-1611128), I also linked to a chapter by Tapio Lokki that updates some of the concert hall research cited by Toole in his books.

Regarding that last quote, there is some very interesting ongoing research regarding concert halls, see https://acousticstoday.org/the-art-...ons-in-research-and-design-kelsey-a-hochgraf/, https://sites.psu.edu/spral/files/2...Hall-Preference-ISRA-Amsterdam-2019-FINAL.pdf, and http://www.davidgriesinger.com/The_Physics_of_auditory_proximity.pptx. Improving the perception of proximity and/or localization is quite different from "nothing but reverberations."

 

[dfuller]

Another data point: the 7th edition of Master Handbook of Acoustics by Everest & Pohlmann. There are three relevant chapters, 20, 21 and 24 which deal with domestic listening/home theatre rooms, home studios and professional control rooms respectively.

Chapter 20: Listening rooms

"Reflections from side walls will provide a wide front sound stage, while absorbers on the side walls will provide a more focused sound stage. Diffusion in the back of the room will add spaciousness and envelopment. It is generally best to balance these attributes. A good approach is to selectively add treatment a little at a time while listening to the effect of each addition. It is best to use any one treatment moderately; it is possible to overly treat a room." (p. 438)

They don't assume the domestic listener to be able to do measurements beyond room dimensions in order to ascertain modes but suggest subjective evaluation for reflections. Some of their recommendations are drawn from Olive and Toole's research (among others). Essentially all reflections need to be below a particular threshold relative to the direct sound, otherwise they will cause problems with imaging. In the figure below, F=floor reflection, E=diffraction (rear wall), C=ceiling, S1 and S2 are side walls and curve B is the threshold below direct sound. Yes, the research mentions speech, but they seem to consider speech intelligibility as an important attribute in a home cinema room. On music: "If the taste of the audiophile is highly specialised, the listening-room characteristics can be designed for relatively optimum results for one type of music. If the listener's taste is more universal, the acoustical treatment of the listening room may require compromises to make it suitable for different types of music." (p. 414)

View attachment 289479


On lateral reflections: "When all of the reflections points are covered, as shown in Fig. 20-7, imaging will probably be much clearer and more precise now that the early reflections have been reduced." (p. 426) But they go on to talk about lateral reflections as something to be tailored to preference.
View attachment 289477
View attachment 289478

Chapters 21 and 24 on home and professional controls rooms argue for greater control of reflections, even lateral, and either LEDE or RFZ designs.

Yep, personally I prefer the non-environment approach since I don't really want to hear the room but I'd really rather not be in an anechoic chamber. Hard front wall and floor end up being enough reflections that the room doesn't sound choked, but are very unobtrusive, especially compared to side wall and ceiling reflections which can be very obtrusive.

But really, the biggest offender in my eyes is diffusion. The vast majority of rooms neither need nor benefit from it and it does exactly the opposite of what is desired in a typical in room response - it tilts it up. Maybe if you have particularly narrow dispersion speakers this is a good idea, but I'd argue against it 99 times out of 100. I've almost never heard it improve a room vs an absorber in the same place and I've heard rooms where they were instantaneously improved by swapping diffusion - especially rear wall diffusion - for absorption.

 

[amirm]

@amirm, can you please provide a direct quote regarding his opinion on large concert halls being "nothing but reverberations?" I believe that this is a significant overstatement or simplification.

Large rooms have critical distance (Dc) after which, all you hear are the reflections and not direct sound. Listeners sit past Dc and hence they hear no direct sound contributions. This is explained in detail in Dr. Toole's book and elsewhere.