Is Toole and Olive's Spinorama model incomplete and limited?

[fpitas]

Well yeah. A couple I'm friends with built a house that is very similar to the 'modern' picture, there were some other people's kids with us and good god it was difficult to stay in the living area.

The reflections were literally uncomfortable and it felt literally like being on a train with all the windows open with 20 people around. So yeah these spaces sound as bad as you think they might.

Yes, I can imagine the acoustics are poor. The general institutional ambience would get to me, too.

 

[NTK]

The room in the picture in the first post is what's described above or is it a different one?

It is the same room. The white paper was written the time when the room was built, around the early/mid 2000's. The picture in the OP was much more recent (may be ~10 years after the initial built?).

There have been modifications made to the lab since it was originally built (almost 20 years ago). For example, please see this post:

I cannot trust the Harman speaker preference score

@Sean Olive - if all loudspeaker preference tests were done in one listening room (harman), wouldn't it be possible that in some other room with different acoustics the results would be different? From the responses that I saw harman's room had substantial bass absorption - listener usually...

www.audiosciencereview.com

 

[Kvalsvoll]

I of course agree that the Harman test room will 'sound different' than most other rooms (since most rooms will sound somewhat different to each other), but can you provide some references to back the claim that this can impact relative loudspeaker preference in listeners under controlled conditions (i.e. some loudspeakers being consistently favored in some rooms)? Thanks!

If sidewall reflections are absorbed, it will prevent faults in the speaker radiation pattern to show. This could be spectral faults or wrong level of the sound going from the speaker into the wall, and if all this sound is absorbed, the fault is then removed, and the faulty speaker will sound similar to a better. Just one example.

 

[Sokel]

It is the same room. The white paper was written the time when the room was built, around the early/mid 2000's. The picture in the OP was much more recent (may be ~10 years after the initial built?).

There have been modifications made to the lab since it was originally built (almost 20 years ago). For example, please see this post:

I cannot trust the Harman speaker preference score

@Sean Olive - if all loudspeaker preference tests were done in one listening room (harman), wouldn't it be possible that in some other room with different acoustics the results would be different? From the responses that I saw harman's room had substantial bass absorption - listener usually...

www.audiosciencereview.com

Ok then.
For the friends who say that it looks like an average room without much treatment,the answer is in:

The listening room itself consists of double-wall constructed shell built by Industrial
Acoustics Corporation (IAC).

That's far,far from average.

 

[JPA]

Ok then.
For the friends who say that it looks like an average room without much treatment,the answer is in:


That's far,far from average.

True, but it also doesn't favor one type of loudspeaker over another.

 

[Sokel]

True, but it also doesn't favor one type of loudspeaker over another.

That was the purpose,wasn't it?

 

[mhardy6647]

The thing to bear in mind about all of this (IMO): Like Monty Python's Camelot...

 

[JPA]

That was the purpose,wasn't it?

Yes, but the OP seems to think it favors box speakers over dipoles and omnis. It doesn't, as far as I can tell.

 

[Duke]

IMO the main question here is whether or not listening to the same loudspeakers in different listening rooms could change relative preference (and if so - in which cases and how?), not whether room characteristics matter / influence sound reproduction itself (they do).

Agreed.

In other words, can we assume that the same relative loudspeaker preference observed in a specific room is valid for any room? The only article I know on this topic suggests that the room has an insignificant effect on relative loudspeaker preference:

Three loudspeakers in four rooms is imo WAY TOO SMALL of a sample size to draw such sweeping conclusions from, ESPECIALLY if the three loudspeakers were broadly similar in directivity. Were any of them horns or horn hybrids? Dipoles? Bipoles? Omnis or quasi-omnis? Cardioids? Line arrays? Were any of them designed with specific placement requirements, and if so, were they used as recommended?

As a thought experiment, suppose that the three loudspeakers were a conventional cone-n-dome speaker, a horn/cardioid hybrid, and a fullrange dipole. Imo there is insufficient evidence to reliably conclude that preference ranking among the three would be room-agnostic (nor placement-within-the-room-agnostic).

 

[dominikz]

If sidewall reflections are absorbed, it will prevent faults in the speaker radiation pattern to show. This could be spectral faults or wrong level of the sound going from the speaker into the wall, and if all this sound is absorbed, the fault is then removed, and the faulty speaker will sound similar to a better. Just one example.

I can understand that line of reasoning - you may have noticed that I gave a similar example in my previous post:

On the other hand, I can easily imagine cases where preference might be influenced - e.g. a good wide dispersion loudspeaker might be preferred in a room with reflective side walls vs a good narrow dispersion loudspeaker, but this advantage might also be lost in another room where side reflections are absorbed, making the two loudspeakers sound more similar.
What would happen if the wide dispersion loudspeaker has uneven directivity and poor on-axis response and the narrow directivity one had even directivity and flat on-axis - would its wide directivity still give the former a chance in some rooms?

Is there any research showing such effects?

Basically here I'm just uncomfortable taking as fact something that hasn't been experimentally demonstrated, even if the conjecture is convincing.

Three loudspeakers in four rooms is imo WAY TOO SMALL of a sample size to draw such sweeping conclusions from, ESPECIALLY if the three loudspeakers were broadly similar in directivity. Were any of them horns or horn hybrids? Dipoles? Bipoles? Omnis or quasi-omnis? Cardioids? Line arrays? Were any of them designed with specific placement requirements, and if so, were they used as recommended?

It was definitely not my intention to make any sweeping conclusions - I was actually trying to be careful with my wording to avoid that impression (but I may have failed at that! ). My intention was mainly to provide a counterpoint to the implied idea that the configuration of the room used for the evaluations makes the existing loudspeaker preference research invalid, and to provide what I thought were appropriate references (which are also quoted in dr. Toole's book).

As a thought experiment, suppose that the three loudspeakers were a conventional cone-n-dome speaker, a horn/cardioid hybrid, and a fullrange dipole. Imo there is insufficient evidence to reliably conclude that preference ranking among the three would be room-agnostic (nor placement-within-the-room-agnostic).

Perhaps, but to my knowledge there is even less evidence to the contrary. The hypothesis could of course be true (it is definitely compelling), but IMHO it needs to be backed by some references.

 

[Duke]

My intention was mainly to provide a counterpoint to the implied idea that the configuration of the room used for the evaluations makes the existing loudspeaker preference research invalid, and to provide what I thought were appropriate references (which are also quoted in dr. Toole's book).

Well if I came across like I was saying the existing research is "invalid", then I communicated poorly.

Perhaps you and I view the research from different angles - I assume you're looking mainly at the preference scores and rankings, while I'm looking for clues about how to build a better loudspeaker. So you and I can look at the same study and arrive at VERY different conclusions! For instance, you cited a particular study as indicating that "the room has an insignificant effect on relative loudspeaker preference", and I get something very different from the SAME study.

In the study binaural recordings were made of each of the three loudspeakers in each of the four rooms so that listeners didn't need to actually be in the rooms. The three loudspeakers were SIMILAR to one another regarding directivity, so significantly different loudspeaker topologies were NOT being compared. When listeners were comparing speakers recorded in a given room, their loudspeaker preference rankings were consistent from room to room. BUT when the different rooms were randomly mixed into the evaluations (easy to do with binaural recordings), the ROOM is what dominated preference!

So, what is the contribution of "the room"? It is the reflections - their arrival times, arrival directions, net power contribution, spectral content, and decay characteristics. Obvously THOSE THINGS (or at least SOME of them) matter enormously as far as preference goes, because when the four different rooms were included in the evaluations, THE ROOM, not THE SPEAKER, is what dominated preference. Or to put a finer point on it, it was the LOUDSPEAKER/ROOM INTERACTION which dominated preference when the room was one of the variables.

So here is my take-away from that study, peering through my "looking for clues" lens: I see a theoretical "window of opportunity" IF we can figure out a way to get a loudspeaker to interact with whatever room it's in MORE LIKE the interaction which takes place in a really "good" room. In other words if we can transplant some of the most desirable loudspeaker/room interaction characteristics into an ordinary room, we probably will have made a worthwhile improvement.

Now let's return to the Harman Shuffler room: Presumably this is a VERY GOOD room, and presumably that LONG time delay before the sidewall reflections arrive tends towards REVEALING a speaker's qualities (otherwise they would have shuffled the speakers up against a side wall). Looking again through my little lens, I'm getting a clearer picture of what the aforementioned "window of opportunity" might look like: It might look like a speaker whose radiation pattern minimizes early sidewall reflections when used in stereo in a "normal" listening room!

But if I were to design such a speaker and sneak it into the Harman Shuffler room, I would not expect it to score well. It would have been deliberately optimized for a very different acoustic environment, and its loudspeaker/room interaction targets would probably NOT be compatible with its placement in the Shuffler room.

 

[dshreter]

A couple of these points have already been mentioned, but to me there's a clear need for more information in three areas:

• Speaker preferences for live rooms
• Wide vs narrow directivity, which is preferable and the relationship to listening distance
• Refining for home theater vs music applications. I would expect home theater to benefit from less reflections whether via absorption or narrow directivity. I would expect music to benefit from spaciousness and wider directivity. But I'd like to know what blind testing would say about this as that's simply my intuition.

 

[Thomas_A]

Wide vs. narrow directivity is also a personal preference, IMO, especially for two-channel. Near or far-field could be as well since that changes the direct to reflected sound ratio. There is no clear-cut answer.

 

[Frgirard]

A couple of these points have already been mentioned, but to me there's a clear need for more information in three areas:

• Speaker preferences for live rooms
• Wide vs narrow directivity, which is preferable and the relationship to listening distance
• Refining for home theater vs music applications. I would expect home theater to benefit from less reflections whether via absorption or narrow directivity. I would expect music to benefit from spaciousness and wider directivity. But I'd like to know what blind testing would say about this as that's simply my intuition.

How do you do for the musical films, Musical comedies, opera filmed... ?

 

[Tangband]

In a stereo system , the phantom sound image illusion is created by the brain only when using two stereo loudspeakers. This fact is in my opinion the biggest flaw with Dr. Tooles and Olives spinorama. Their statement is - mono is good enough to make conclusions about the sound of a loudspeaker. This is also true, I believe,- If we are talking about only one loudspeaker.
Dr. Toole stipulates that the stereo system is seriously flawed, and he is also correct about that.

But….You most often dont listen to mono with only one speaker, you always have two speakers to make the stereo illusion real for the brain. The spinorama dont care about this fact.

There is much more investigations to be needed about phantom images when using two loudspeakers in stereo - in my opinion.

Dr.Toole and Olive has done a great job of what makes a loudspeaker sound good - at least in mono, and maybe also in a multichannel homecinema setup.

 

[Tangband]

Wide vs. narrow directivity is also a personal preference, IMO, especially for two-channel. Near or far-field could be as well since that changes the direct to reflected sound ratio. There is no clear-cut answer.

My experience ( and some others ) is that a wide directivity is prefered by most people in two-channel playback if listening in a big room, and with 5.1 cinema sound a more narrow directivity is in most cases prefered.

 

[Mnyb]

Also not well defined , what is a big room or a small room this also hampers these discussions.
It may depend on where in the world you live ?

Any agreed upon definitions about that ?

 

[Geert]

Also not well defined , what is a big room or a small room this also hampers these discussions.
It may depend on where in the world you live ?

Any agreed upon definitions about that ?

Harman uses RT60 as the leading indicator.

 

[Mnyb]

Harman uses RT60 as the leading indicator.

Ok so it’s not only really big or small but also how reverberant the room is , so the limit could vary.
At which rt60 ar we considered to have big room ? If such simplified reasoning makes sense .

 

[Geert]

Ok so it’s not only really big or small but also how reverberant the room is , so the limit could vary.
At which rt60 ar we considered to have big room ? If such simplified reasoning makes sense .

There are no hard numbers. Let's say RT60 for a normal living room is about 0,4 sec to 0,7 sec, give and take. The low end of that range is also what's being adviced for optimal HiFi sound. A big room I would say is from 0,9 sec sec up. When using reverb units in mixing RT60 > ~2 sec is no longer a room but a 'hall', just to give you an idea (at that point also predelay becomes important).