Question to Kees

[Purité Audio]

Kees just spotted you online, where do you stand regarding the absorption of first reflection arguement?
Thanks Keith.

 

[amirm]

I feel so obsoleted!

 

[Purité Audio]

There's always someone, better,cheaper and younger than you!
Keith

 

[amirm]

It had to happen one day. I guess today is the day!

 

[Purité Audio]

Kees Hi, just spottedyouonline again, AJ and Amir have been having a protracted argument over first reflections, Toole states that some sound engineers prefer absorbing first reflections when they are 'working' but might prefer more lateral reflections at 'home'?
I just wondered if you had an opinion?
Keith

 

[Phelonious Ponk]

Kees? Come in Kees...

 

[Thomas savage]

Well, all these middle aged fan boys... How can he resist

 

[Phelonious Ponk]

Well, all these middle aged fan boys... How can he resist

I don't know him. Just trying to be helpful. Oh and I deny the "middle-aged" accusation. I don't expect to live 128 years, so this ain't the middle.

Tim

 

[amirm]

Kees Hi, just spottedyouonline again, AJ and Amir have been having a protracted argument over first reflections, Toole states that some sound engineers prefer absorbing first reflections when they are 'working' but might prefer more lateral reflections at 'home'?

Keith, it seems my banter with AJ has caused some confusion. There is no conflict between my views, Dr. Toole's and AJ's with regards to the topic in general. The issue I point out is that AJ's read of the topic is very casual and is putting all reflections in the same bucket. Each reflection has a different psychoacoustics effect which Dr. Toole goes through extreme amount of research to demonstrate.

Here is one example from Dr. Toole's book:

"Bech separately examined the influence of several
individual reflections on timbral and spatial aspects of
perception. In all of the results, it was evident that signal
was a major factor: Broadband pink noise was more
revealing than male speech. In terms of timbre changes,
only the noise signal was able to show any audible effects
and then only for the floor reflection; speech revealed no
audible effects on timbre.

[...]

Further investigations
revealed that the detection was based mainly on
sounds in the 500 Hz–2 kHz range, meaning that ordi-
nary room furnishings are likely to be highly effective at
reducing first reflections below threshold, even for the
more demanding signal: broadband pink noise (see
Section 21.3)."

And later:

"It is probably safe to
assume that the floor will have carpet (best if it is a clipped-pile, jute-backed,
acoustically porous type), installed over a thick felt cushion so that the combination
behaves like a broadband absorber (see Figure 21.3)."

[...]

"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."

So as you see clearly, not all reflections are good according to Dr. Toole. See my article on further data on that: http://www.audiosciencereview.com/forum/index.php?threads/perceptual-effects-of-room-reflections.13/

Side reflections are the only ones that are beneficial in themselves. Other reflections are only beneficial to the extent they increase sound power (so dead rooms are no good).

Here is the fundamental psychoacoustic concept: because we have two ears, the way each one hears sound is completely different with respect to the direction it arrives. A side reflection arrives at the two ears very differently with respect to time delay (one ear is farther than the other) and timbre (acoustic shadow of the head). The high differential between what is heard in the two ears causes a sense of spaciousness (at the right levels).

A reflection that arrives from the front does not have that attribute. Both sounds arrive at the same time and with the same timbre. As a result, it has a very different psychoacoustic effect. Further complicating matters, is the fact that the ceiling bounce that has the same characteristic in this regard, has yet again a different effect due to its height!

The role of reflections in how we perceive sound is the most complicated topic in sound reproduction. It literally took me reading and understanding 50+ papers over a lengthy period of time for the picture that Dr. Toole writes about in his book to materialize in a consistent story. No casual read of his work will get you there.

Complicating all of this is the process of adaptation which the brain uses to dismiss the room reflections in general! That is why rooms above certain frequency sound like the speaker you are using, rather than the room.

So when asking about reflections, you need to quantify it:
1. Is it the first reflection or other?
2. Which direction is it coming from?
3. How live is the room already?

 

[Purité Audio]

Amir Hi, yes I do ,sort of understand , I have read Sound Reproduction three times!
Almost understand it , I just wondered as Kees is in the business what he thought re the particular work versus listening for pleasure debate?
Keith

 

[AJ Soundfield]

There is no conflict between my views, Dr. Toole's and AJ's with regards to the topic in general.

Agreed.

The issue I point out is that AJ's read of the topic is very casual and is putting all reflections in the same bucket.

Nope. Don't own a bucket. One of us has been follow all the research for decades, the other is Johnny come lately.
You really need to brush up on Greisinger, JJ, Salmi, etc, etc. to get the full scope....and why Toole's full bipolar M1s were so highly rated in NRC blind tests....and why Toole himself misses them and his largely untreated "concert hall" room.
You are misunderstanding your snippets contextually.

 

[amirm]

Agreed.


Nope. Don't own a bucket. One of us has been follow all the research for decades, the other is Johnny come lately.
You really need to brush up on Greisinger, JJ, Salmi, etc, etc. to get the full scope....and why Toole's full bipolar M1s were so highly rated in NRC blind tests....and why Toole himself misses them and his largely untreated "concert hall" room.
You are misunderstanding your snippets contextually.

That's not "all" the research or remotely close to it. Every time you see a quote from Dr. Toole in his book from another researcher, you need to go and find those papers and read them. And references within them. Vast majority by the way are NOT in public domain or on AES -- your two sources of information.

You also need to spend time with the researchers. It is one thing to read a book, but entirely different matter spending time with the researchers.

Finally, the psychoacoustic research is not on speakers, nor is it performed blind. You are mixing acoustic topics which is perfect proof of going by tidbits you have read here and there. And causing confusion on the topic.

Please put aside your competitive nature and let's get the data out. You are creating cloud of confusion where there should be none.

 

[AJ Soundfield]

You also need to spend time with the researchers. It is one thing to read a book, but entirely different matter spending time with the researchers.

Ok, you got me there.
So when you spent all that time with JJ, what did he mean by "perceptually indirect" and good speakers having "indirect radiation" capabilities? What did he mean in the papers I've linked several times, about the plane waves in the direct response of your forward radiators being incapable of simultaneously reproducing the indirect spatial information?
When you sat with Toole, why did the bipolar Mirage M1s rate so highly in NRC tests? Why were all those reflections from the rear in his concert hall room unobjectionable, in fact, the opposite?
TIA.

Btw, Kees has most likely read my writings on HA about "treatments", so he is most likely aware of what the research shows for home vs production "listening".

 

[amirm]

Ok, you got me there.
So when you spent all that time with JJ, what did he mean by "perceptually indirect" and good speakers having "indirect radiation" capabilities? What did he mean in the papers I've linked several times, about the plane waves in the direct response of your forward radiators being incapable of simultaneously reproducing the indirect spatial information?
When you sat with Toole, why did the bipolar Mirage M1s rate so highly in NRC tests? Why were all those reflections from the rear in his concert hall room unobjectionable, in fact, the opposite?
TIA.

Btw, Kees has most likely read my writings on HA about "treatments", so he is most likely aware of what the research shows for home vs production "listening".

All of this is competitive, repetitive non-sense having nothing to do with Keith's question. Let him have his thread and don't kick more sand into the discussion. Next post that has more hero worship and nothing else will be deleted.

 

[Kees de Visser]

Actually my Mac was online but I wasn't looking

Not sure if I have much to add. I'm a recording engineer, mostly doing classical music on location. Very few classical engineers use a mobile (truck) as a control room so most of us just use a more or less suitable room close to the musicians in the concert hall or church.
Those rooms are rarely acoustically treated and you wouldn't want to imitate something like that at home. Here are three examples of typical control rooms used by renowned recording teams:

Polyhymnia control room in the Concertgebouw, Amsterdam.

Channel Classics control room in the Palace of Arts, Budapest. DSD/SACD recording, mixed on location.

Norwegian Label 2L recording in a church, monitoring with headphones.

Apart from the Channel Classics setup which is directly mixed (stereo + surround) with an analog console, the two others are probably mixed in their home-based studios. Nevertheless the critical process of positioning the musicians and microphones is done by using rather compromised control rooms. The final result can be excellent nevertheless. Headphones are always used to double-check. Speakers however are much better for listening with several persons in the room and discussing at the same time.
Adaptation to the sound is important and if time permits, we try to spend at least a few hours listening to well known recordings to get familiar with the sound of an unknown control room.

So, where do I stand? I don't mind some reflections, as long as they are symmetrical (L/R). If a control room is really horrible I'll use headphones. Requirements for pop studios might be different.

A few years ago I attended a listening session in an anechoic chamber (zero reflections). Bruno was there too btw. We could compare our own and other recordings on a stereo and 5.0 setup. Very interesting. The difference between stereo and surround was quite large. Needless to say that stereo doesn't give much envelopment in that room. Pity we couldn't hear 3D audio like Auro then. I'm inclined to say that stereo needs a room, surround and 3D not so much.

Cheers,
Kees

 

[Purité Audio]

Kees Hi, thanks so much for answering my question I didn't meant to harang you into answering!
I am very keen to try 3D or immersive sound , I am going to be using the Kiis ( when they arrive ) and an Illusonic processor, Christof at Illusonic has been experimenting with multiple channels including 'height'.
I realise it is an imposition and obviously you don't have to answer, but I have no real experience of professional recording ,I would like to ask,
is every recording assignment different interns of microphone placement , presumably you are always limited by physical dimensions , the amount of time and budget?
It would be great to hear a brief explanation of exactly how you make a recording and the elements you consider important.
Thanks again,
Keith.