The perfect speaker is room dependent - wide vs. narrow directivity and more

[test1223]

If highly damped room does not provide envelopment, what about diffuse the sound using diffuser? I imagine the sound will hit our ears , but majority of sound will scatter around in the room, very few end up in our ears eventually, others just die down. If what I said is true, what is the difference between diffuse and reflection and do they provide envelopment?

Yes if the diffuser works well it will create a more diffuse sound field.
In detail it is a bit more complicated. A diffuse sound field will guaranty envelopment but it is very hard to achieve in typical listening rooms. Since the human hearing has only two one dimensional Sensors (eardrums) with a directional frequency dependent filter in front of it (ear and head) there are some tricks, which also create envelopment without a diffuse sound field. One good trick is a reflection which reaches the ear at about 60°. Good concert hall are build around this effect.

 

[Descartes]

Since discovering multichannel music reproduction with well recorded SACD DSD material with 5.1, I gave up stereo listening to multichannel!
I know enjoy more music in Atmos or SACD on a 9.4.6 system using KEF speakers than in stereo!

My dream is this except it is way out of my price range!

https://www.genelec.com/-/reference...r-morten-lindberg-s-stunning-immersive-studio

 

[hvbias]

I think a wide dispersion speaker is to be preferred when striving for the best.
I say this both from experience and from theory.

Yes, a narrow dispersion speaker can often sound better in a bad sounding untreated room. Though I know many examples from experience where it's the opposite too.
But the preference for wide dispersion speakers becomes clear when you have a good sounding room or even a minorly treated room.

A wide dispersion speaker will throw a much bigger soundstage.
I've listened in a fairly large room with heigh ceilings which had virtually no absorption but did have a lot of diffusion and with a wide dispersion speaker the whole room came alive and the soundstage was absolutely huge. And compared this in that room with more narrow dispersion speakers which had waveguides (among them K+H O300) and the soundstage just collapsed to a mostly inbetween the speakers ordeal.

If you want to dampen the off-axis sound then a carpet and curtains against the sidewalls will already do that in the treble similar to a more narrow dispersion speaker would do on bare walls / floor. But the big difference is that with bare walls / floor the sound will keep reflecting without further absorption, while with absorption the reverb time itself shortens. I think the second way where reverb time is shortened is to be greatly prefered.

For serious listening rooms the trouble is in absorbing the deep bass, not the treble which is easy. It's both easier to get to a tonal balance and soundstage you like with absorption and diffusion with a wide dispersion speaker and the endresult will likely be better regarding reverb time and soundstage.

Goes without saying that a smooth off-axis is preferred ofcourse. With both wide and narrow dispersion speakers.

You can make a narrow dispersion (waveguide) speaker have a very deep and wide soundstage by toeing them inward. As a primarily classical listener this is very important to me. From all the narrow vs wide dispersion speakers I've had (assuming exceptional/even power response), I much prefer this as you can still retain sharp imaging as opposed to the unfixable constant diffuse imaging of wide dispersion speakers. I do prefer wide in our home theater where the rest of my family should get good fidelity as well (most important speech intelligibility at the very least). Keele CBT line arrays are the best I've heard for theater use, sadly it looks like Parts Express have discontinued their kits for them.

 

[Bjorn]

You can make a narrow dispersion (waveguide) speaker have a very deep and wide soundstage by toeing them inward. As a primarily classical listener this is very important to me. From all the narrow vs wide dispersion speakers I've had (assuming exceptional/even power response), I much prefer this as you can still retain sharp imaging as opposed to the unfixable constant diffuse imaging of wide dispersion speakers. I do prefer wide in our home theater where the rest of my family should get good fidelity as well (most important speech intelligibility at the very least). Keele CBT line arrays are the best I've heard for theater use, sadly it looks like Parts Express have discontinued their kits for them.

One has to take into the account the acoustics and dimension of the room. With freedom in acoustic treatment it's possible to achieve spaciousness for many listeners with almost any speaker directivity, though the beamwidth will always benefit from being uniform above the Schroeder frequency.

FIY: New CBT speakers are coming, but not as kits. A great benefit with a CBT is the avoidance of floor reflections and greatly minimization of ceiling reflections, which are both detrimental to sound quality.

 

[test1223]

Hello,

in another thread @fluid posted a very interesting presentation of David Griesinger about envelopment research findings in small rooms.
http://www.davidgriesinger.com/laaes2.pdf

FIY: New CBT speakers are coming, but not as kits. A great benefit with a CBT is the avoidance of floor reflections and greatly minimization of ceiling reflections, which are both detrimental to sound quality.

Great! Line array speakers and wave forming array are very interesting.

There is something with these speakers with a higher beam which gives the sound some kind of "punch" in all frequencies. It is very hard to describe and I don't know if there is any research in that phenomena. It might have to do with the perception of the whole body with sound via vibration since much more sound is hitting the listeners whole body originated from one direction. In a very loud disco you also get a similar but somehow different feeling of being punched even by high frequencies. But in the disco case it is clearly a perception of vibration.

 

[Tangband]

Hello,

I want to discuss here the differences of wide and narrow directivity of very good speakers in context with room acoustics and more.

One perfect speaker for all rooms. I don't think so.
On conclusion of the research at of @Floyd Toole and others are that a good speaker sounds good in any room. In general I will agree with this statement, but if you have a closer look at only very good speakers and different rooms and positions of the speakers and the listening position you will find that the perfect speaker is room dependent.

Listening distance
The listening distance is one of the most important parameter here. If you have a look at stereo you will find that you will need a amount of later reflections to get a feeling of "been surrounded by the sound". Omnidirectional speaker achieve this very well since there are more reflections of the room. But you will have a disadvantage with these speakers, the details of the sound will be masked by the reflections which makes the sound "soft", "washy" or "inexact". On the opposite side is a headphone. You have no additional reflections and the sound is "clear" or "exact" but you will have a poor or no feeling of being surrounded by the sound (binaural recording are different but I will not go into detail here). So there is a sweet spot of the ratio of direct sound to later reflected sound. It can be seen in the EBU recommendations on page 6 where the reverberation time at the listening position is recommended. I think this recommendations are valid.

Short listening distance wide directivity
If you follow this path you will need a speaker with wide directivity if you listen at short listening distances. Linkwitz invented a speaker which creates a good feeling of being surrounded by the sound despite the short listening distance. which is very rare to get. This is done by having a omnidirectional speaker and put them in the middle of the room.

Long listening distance narrow directivity
If you have a longer listening distance you will need a speaker with a narrow directivity to get the recommended reverberation time at the listening position with the speaker. And the speaker have do be beam a lot to achieve the goal. E.g. at 2.5m a typical 2 way speaker with 17cm bass beams a lot to wide.

There are plenty other parameter which are important
How constant is the directivity is over frequency, speaker with narrow beam and extra backfiring speaker or dipol like characteristics, first side wall reflection absorb or not, side wall reflections at 60° ideal?, unsymmetric placement is bad but what differences are still okay...

How to get perfect sound?
And the question which speaker room combination is perfect and how should the ultimate goal look like? A "standard" speaker with narrow directivity in a studio like dry room? All horns oben back in a big room with diffusing walls? Line arrays (horizontal wide and vertical narrow diretivity)?

Best
Thomas

There are many things that matters in two channel playback . You cant say that you always need narrow beaming directivity on long distances. It depends on how much damping there is in the room, and the size of the room, where the walls are - and where the placement of the speakers are.

Being a semiproffesional recorder of acoustical instruments, its very clear to me and many people that two channel playback is not a photoprint of the real event . Not even close. Its, at its best , a good illusion. Just like Toole teaches. And he is right.

A big room with long distance listening can benefit from narrow beaming directivity loudspeakers , or speakers with wide beaming directivity. It depends on many things. The amount of damping in the room, and the distance to sidewalls, and the room size. If there is much acoustical treatment in the room, and a big rug on the floor , you might not need narrow directivity loudspeakers.

In my opinion: For best illusion of stereo playback in a listening room, about 20-25 ms delayed reflections from the sidewalls are optimal to fill in the stereo system faults ,- this is regardless of speakers with narrow directivity or not . This demands, unfortunately, a rather big room. In such optimal circumstances, it might also sound better with loudspeakers with wide directivity. You have to try in every case. The optimal room for two channel playback is not a room with zero acoustic reflections, because the stereo system is seriously flawed.

Optimal stereo playback is not something that is exactly the same in every room. Its very different, depending on the room size, the acoustical treatment and even the material the walls are made of.

As you see, I agree with a lot of your statements, but maybe not all of them . I also have had the jbl 530 loudspeaker, - This is a narrow beaming directivity loudspeaker. It had some benefits, but overall my Genelec 8340 with its wider directivity and lower distortion is sounding much better , even when I sit 4 meters away from them in a big, rather untreated listening room.

With 5.1 cinema sound in an acoustical treated room thereˋs a different story …..

 

[test1223]

There are many things that matters in two channel playback . You cant say that you always need narrow beaming directivity on long distances. It depends on how much damping there is in the room, and the size of the room, where the walls are - and where the placement of the speakers are.

Being a semiproffesional recorder of acoustical instruments, its very clear to me and many people that two channel playback is not a photoprint of the real event . Not even close. Its, at its best , a good illusion. Just like Toole teaches. And he is right.

A big room with long distance listening can benefit from narrow beaming directivity loudspeakers , or speakers with wide beaming directivity. It depends on many things. The amount of damping in the room, and the distance to sidewalls, and the room size. If there is much acoustical treatment in the room, and a big rug on the floor , you might not need narrow directivity loudspeakers.

In my opinion: For best illusion of stereo playback in a listening room, about 20-25 ms delayed reflections from the sidewalls are optimal to fill in the stereo system faults ,- this is regardless of speakers with narrow directivity or not . This demands, unfortunately, a rather big room. In such optimal circumstances, it might also sound better with loudspeakers with wide directivity. You have to try in every case. The optimal room for two channel playback is not a room with zero acoustic reflections, because the stereo system is seriously flawed.

Optimal stereo playback is not something that is exactly the same in every room. Its very different, depending on the room size, the acoustical treatment and even the material the walls are made of.

As you see, I agree with a lot of your statements, but maybe not all of them . I also have had the jbl 530 loudspeaker, - This is a narrow beaming directivity loudspeaker. It had some benefits, but overall my Genelec 8340 with its wider directivity and lower distortion is sounding much better , even when I sit 4 meters away from them in a big, rather untreated listening room.

With 5.1 cinema sound in an acoustical treated room thereˋs a different story …..

We are almost on the same page. Some comments:

The room is of cause important but you aren't able to modify a room that a nearfield monitor provides enough direct sound at 3 or even 4m. And you will always hear the lack of direct sound no matter how good the sound will be in all other aspects.

Both speakers Genelec 8340 and JBL 530 are nowhere near to perform good at 4m. Both RT60 can't be that low as recommend in the ebu paper (speaker as a source and mic at listening position), even if you place a lot of absorption material in the room it is impossible in practice to get a good enough RT60 curve with one of the speakers. The sound power di is to high at least in the region from 300Hz to about 1kHz.

At 4 meter it is possible to get good RT60 levels with a speakers like the biggest genelec 1236A in an untreated room.

Besides the right sound power di of a speaker there are obviously many other important parameters which let you choose one speaker over another. But that doesn't prove the necessity of having a constant and relatively low RT60 at the listening position wrong.

As I mentioned you can try different listening distances with the same speaker and you will find that the genelec 8340 will sound much better at about 1m than at 4m. And at about 1m the RT60 will be much closer to the recommended value/curve. If you did this with a few speakers and rooms you will begin to hear a pattern how a lower or a higher amount of direct sound sounds.

 

[Tangband]

We are almost on the same page. Some comments:

The room is of cause important but you aren't able to modify a room that a nearfield monitor provides enough direct sound at 3 or even 4m. And you will always hear the lack of direct sound no matter how good the sound will be in all other aspects.

Both speakers Genelec 8340 and JBL 530 are nowhere near to perform good at 4m. Both RT60 can't be that low as recommend in the ebu paper (speaker as a source and mic at listening position), even if you place a lot of absorption material in the room it is impossible in practice to get a good enough RT60 curve with one of the speakers. The sound power di is to high at least in the region from 300Hz to about 1kHz.

At 4 meter it is possible to get good RT60 levels with a speakers like the biggest genelec 1236A in an untreated room.

Besides the right sound power di of a speaker there are obviously many other important parameters which let you choose one speaker over another. But that doesn't prove the necessity of having a constant and relatively low RT60 at the listening position wrong.

As I mentioned you can try different listening distances with the same speaker and you will find that the genelec 8340 will sound much better at about 1m than at 4m. And at about 1m the RT60 will be much closer to the recommended value/curve. If you did this with a few speakers and rooms you will begin to hear a pattern how a lower or a higher amount of direct sound sounds.

Its an interesting discussion , but the fact is :

1. Regarding to Dr Tooles research at Harman , there are no such conclusion .
If the loudspeaker have good directivity, it gonna be prefered by most listeners . It doesnt matter much if its narrow beaming or wide beaming .

2. I prefere wide beaming good directivity loudspeakers soundwise no matter how the room is acoustical treated . I think they sound more natural, more like the real concert experience .

3. You seems to forget ( or you dont mention it ) that the stereo system is seriously flawed - and for good two channel listening you NEED some late reflections from the sidewalls .

4. There is also the precedence effect thats gonna dominate if you listen to speakers at a distance longer than 5 ms soundtravel , meaning distances longer than 1,7 meters .

This effect , gonna make your brain zoom in to the first arriving sound ( the direct sound from the speakers ) and your brain gonna attenuate the later reflected sound coming from the room as much as -10 dB !

Did you know this ?

Precedence effect - Wikipedia

en.m.wikipedia.org

The consequences of this is that the direct sound from the loudspeaker is the most important thing , and the reverberant sound from the room gonna be much less disturbing for the brain than the measurements shows.

This is a fact , and also makes decisions based on measurements from listening position very hard to predict , only information from those measurements are valid from aprox. 300 Hz and below .
At longer distances than 5 ms soundtravel , ( longer than 1.7 meter from the loudspeaker ) , the brain starts to select sounds, and the microphone takes up all the sound .

The picture shows a good wide beaming directivity loudspeaker that gonna sound good everywhere , even from distances of 4 meters . The Revel m106.

 

[Bjorn]

One reason that many think they prefer a wide dispersion speaker could be because very few has actually heard a speaker with a narrow and uniform directivity over a wide frequency area. Most so called narrow speakers either looses the directivity quite high in frequency or they are not particular uniform.

 

[eliash]

Thanks for the valuable discussion! Coming late to this thread, I think it hits the point.
...Having given up hope to find immediately fitting speakers w/o adaptation to the room and (some, even not so cheap) speakers for a "desirable" sound...i. e. considering the time and work to match certain* speakers (and wall treatment) to the room don't make it worthwhile for me to look for "better" ones...

(*Dynaudio Focus 220 1st gen)

 

[test1223]

One reason that many think they prefer a wide dispersion speaker could be because very few has actually heard a speaker with a narrow and uniform directivity over a wide frequency area. Most so called narrow speakers either looses the directivity quite high in frequency or they are not particular uniform.

Yes!
On top the typical highly treated test listing room with a lot of absorption creates some obvious results. A wider dispersion in the higher frequencies even to the mids is highly beneficial here. I would go one step further and claim that a speaker beyond a constant di which has a narrow beam in the bass and an increasingly wider dispersion towards the higher frequencies would nail such a room. Such speakers are almost impossible to build since a single driver created exactly the opposite and jumps in the di aren't good.

 

[Tangband]

Yes!
On top the typical highly treated test listing room with a lot of absorption creates some obvious results. A wider dispersion in the higher frequencies even to the mids is highly beneficial here. I would go one step further and claim that a speaker beyond a constant di which has a narrow beam in the bass and an increasingly wider dispersion towards the higher frequencies would nail such a room. Such speakers are almost impossible to build since a single driver created exactly the opposite and jumps in the di aren't good.

You still need some late reflections from the sidewalls for really good 2-channel sound and thats best done with wide beaming directivity loudspeakers ,so any conclusions that listening at loudspeakers at 3 meters or longer distances would benefit having loudspeakers with narrow beaming directivity is a false statement .
This is very room and acoustical treatment dependent.
You should change the threads name , and put a ? after the first sentence.

Your statement is true though if one will set up a really good 5.1 channel system .

But not with 2-channel playback , not in my opinion.

 

[Descartes]

One reason that many think they prefer a wide dispersion speaker could be because very few has actually heard a speaker with a narrow and uniform directivity over a wide frequency area. Most so called narrow speakers either looses the directivity quite high in frequency or they are not particular uniform.

KEF LS50 Meta is narrow directivity and sound great no matter where you sit

 

[Bjorn]

KEF LS50 Meta is narrow directivity and sound great no matter where you sit

KEF LS50 is an example of what I described. A speaker that looses it's directvity high in frequency. And it's not very uniform either.
With a directivity varying from 120° to 170° above 1 kHz, that wouldn't be considered narrow by the way.

 

[Tangband]

KEF LS50 is an example of what I described. A speaker that looses it's directvity high in frequency. And it's not very uniform either.
With a directivity varying from 120° to 170° above 1 kHz, that wouldn't be considered narrow by the way.

Can you show us a loudspeaker that has that uniform directivity that you talk about ? What does it look like ?

 

[Bjorn]

Can you show us a loudspeaker that has that uniform directivity that you talk about ? What does it look like ?

Very large horn speakers can offer both. The one below would be an example of a uniform directivity over a quite wide frequency area. It's showing a beamwidth of about 100° with indoor neafield measurement, but in reality it's narrower.

That's also the case here with another horn. Indoor measurements in nearfield tend to become wider than what it actually is. But also here you can see a very uniform directivity from 200 Hz till 18 KHz.

Here's a synergy horn which is both narrow and quite constant:

Dipoles can also be fairly narrow and uniform, but obviously will send out the energy backwards as well:

Extremely narrow (beamwidth of less than 60-70°) and uniform is difficult to achieve. The Quad speaker below is very narrow, but exhibits quite bit of polar lobing.

Or super narrow directivity speakers tends to beam (become narrower higher in frequency) as seen here (showing front and backwave since it's a dipole):

Then we have speakers with medium wide beamwidt around 120° that maintains it quite low. Like the Gradient Helsinki below.

Generally it's easier to design a speaker with wide and constant beamwidth. Apart from lobing around 9-10 KHz and some narrowing in the very highs, we can see that it's able maintain a directivity of 180° over a wide area. Best "facial" polar so far?

A speaker that is able to maintain the direcitivity all the way down the Schroeder frequency is the ideal. However, extremely few speakers do that. Typically commercial speakers will start to loose the directivity already around 1 KHz or some a bit lower. That's a big compromise. The vertical directivity is of course another matter.

It may be worth remembering that in studios and mastering rooms, the sidewall reflections are almost always greatly attenuated. In many of them, they have a late lateral contribution from the rear with diffusers instead. That is a more accurate approach and gives a better insight to the recordings. So that fact that we need to have side wall reflections for a good sound when it's seldom used where music is mixed/mastered is very questionable. It very much depends on several factors.

 

[Duke]

FANTASTIC POST, Bjorn! Thank you for taking the time.

Very large horn speakers can offer both. The one below would be an example of a uniform directivity over a quite wide frequency area. It's showing a beamwidth of about 100° with indoor neafield measurement, but in reality it's narrower.
View attachment 219718

That's also the case here with another horn. Indoor measurements in nearfield tend to become wider than what it actually is. But also here you can see a very uniform directivity from 200 Hz till 18 KHz.

View attachment 219720

Wow! Are either of those your designs?

Dipoles can also be fairly narrow and uniform, but obviously will send out the energy backwards as well:
View attachment 219724

That's incredible pattern uniformity for what is presumably a non-horn speaker. The designer is obviously doing something very deliberate in addition to using dipole radiation for pattern control. Can you tell us what speaker that is?

A speaker that is able to maintain the direcitivity all the way down the Schroeder frequency is the ideal. However, extremely few speakers do that. Typically commercial speakers will start to loose the directivity already around 1 KHz or some a bit lower. That's a big compromise. The vertical directivity is of course another matter.

In the event that "all the way down to the Schroeder frequency" is impractical, one implication of David Griesinger's work is that pattern control down into the 500-1000 Hz region is still psychoacoustically worthwhile:

“Localization – and the perception of clarity – is a high-frequency phenomenon in reverberant spaces. The information content of speech and much music, and the sense of sonic distance, the perception of clarity, the ability to sharply localize instuments, and the ability to separate multiple sound streams, all depend critically on the harmonics above 1000 Hz.”

“Clarity is a HIGH FREQUENCY phenomenon – 800Hz and above.”

"Transients are not corrupted by reflections if the room is large enough - and 10ms of reflections free time is enough." (Earl Geddes points out that Griesinger's 10 milliseconds corresponds to the reflection-free interval needed for the ear to get good data down to 700 Hz.)

“The information content of speech is (almost) entirely in frequencies above 500Hz.”

JBL seems to have aimed for goal posts implied by Griesinger in the design of the M2, rather than going all the way down to Schroeder.

That being said, I assume you find pattern control all the way down to Schroeder to be worth the extra size and effort, at least when accomplished by horn loading. I agree based on the full-range horn speakers I've spent a bit of time with (Edgarhorns, reproduction Hartsfields, Klipsch Jubilee), but oboy they are big.

It may be worth remembering that in studios and mastering rooms, the sidewall reflections are almost always greatly attenuated. In many of them, they have a late lateral contribution from the rear with diffusers instead. That is a more accurate approach and gives a better insight to the recordings. So that fact that we need to have side wall reflections for a good sound when it's seldom used where music is mixed/mastered is very questionable. It very much depends on several factors.

Agreed!

Harman's listening tests placed a single speaker along the centerline of a 22-foot-wide room, and the resulting abnormally-long lateral reflection path lengths precluded the presence of "early" lateral reflections. So if there is a downside to the increased early-reflection energy of wide-pattern speakers in a "normal" set-up, it was not included in Harman's blind listening evaluations.

 

[Kvalsvoll]

Seems to be a common misconception about speaker directivity and room decay.

Radiation pattern of the speaker does not change the slope of the decay, but more controlled and narrow pattern will give a better initial early decay drop, and reduces the relative level of the reflected sound energy compared to the early direct sound.

Slope:

Initial drop:

Wide vs. narrow speaker:

 

[Kvalsvoll]

“Localization – and the perception of clarity – is a high-frequency phenomenon in reverberant spaces. The information content of speech and much music, and the sense of sonic distance, the perception of clarity, the ability to sharply localize instuments, and the ability to separate multiple sound streams, all depend critically on the harmonics above 1000 Hz.”

“Clarity is a HIGH FREQUENCY phenomenon – 800Hz and above.”

I do not have the original text/paper referenced here, but what happens below 800hz does affect localization, perceived appearance of the rendering of objects, and separation between objects.

If clarity means definition and preservation of the original instruments timbre, then clarity is relevant across the whole frequency range, including low bass.

For localization and appearance of objects, the low mid range around 100-200hz up to say 1000hz is very important. Radiation pattern of the speakers, combined with room acoustic properties, defiens the limits of achievable performance here.

To verify importance of radiation pattern and decay structure in this freq range, it is crucial to actually have a room and speaker system that has sufficient performance to show the differences. Then it is possible to conduct controlled experiments, say, for different speaker radiation patterns.

 

[Tangband]

When I started doing my own recordings, I noticed that 2 channel playback is not an exact copy of the recorded event.

Its just an illusion that you listen to , and a rather flawed one. I ´m still convinced that for really good illusion in 2 channel playback its beneficial with some late 20-25 ms first reflections from the sidewalls in the (big) listening room, to fill up the stereo system faults.

This is special for 2 channel listening because it is such a flawed system. 5.1 systems dont need this trick.

To understand this , one needs to go back in the recording chain and make your own two channel recordings in real concert halls.

So, in my opinion , late reflections in the listening room is not something bad . Whats needed is good directivity loudspeakers. They can be either narrow or wide beaming, but the directivity has to be good.

You get more late reflections from the sidewalls in a big room with wide beaming directivity speakers, which is good for the sound.

In a smaller room, you dont have that 20-25 ms reflections needed for a good illusion. The first reflections in the small room from 5 - 10 ms gonna make the sound less clear. Then you can experiment with narrow beaming directivity loudspeakers. But this is not an optimal solution for two channel playback.

Almost noone in this thread are mentioning the precedence effect . This is not something one can ignore, and its very real. This is the way we hear things.

Precedence effect - Wikipedia

en.m.wikipedia.org

This effect gonna dominate if you listen to speakers at a distance longer than 5 ms soundtravel , meaning distances longer than 1,7 meters .

This precedence effect gonna make your brain zoom in to the first arriving sound ( the direct sound from the speakers ) and your brain gonna attenuate the later reflected sound ( 5 ms or more ) coming from the room as much as -10 dB !

The brain starts selecting sounds ( with reflections coming 5 ms or longer ) , and the microphone takes up all the sound.

This is also why the optimal listening position ( maybe 7 meters away ) in the concert hall is not the same as the optimal microphone position ( maybe 1 meter away from the instrument ) in a recording situation.

The brain and the microphone works very different at distances . This is why you cant trust measurements from the listening position , higher than about 300 Hz .

From Tooles AES paper :

“Most reflections arrive from directions different from the direct sound, and perceptions vary considerably. Two ears and a brain have advantages over a microphone and an analyzer. The fact that the perceived spectrum is the result of a central (brain) summation of the slightly different spectra at the two ears attenuates the potential coloration from lateral reflections significantly [34]. If there are many reflections, from many directions, the coloration may disappear altogether [35], a conclusion to which we can all attest through our experiences listening in the elaborate comb filters called concert halls. Blauert summarizes: “Clearly, then, the auditory system possesses the ability, in binaural hearing, to disregard certain linear distortions of the ear input signals in forming the timbre of the auditory event.”

“It was in this room [Dr. Toole’s Reference IEC room at National Research Council] that experience was gained in understanding the role of first reflections from the side walls. The drapes were on tracks, permitting them to easily be brought forward toward the listening area so listeners could compare impressions with natural and attenuated lateral reflections (see Figures 4.10a and 8.8). In stereo listening, the effect would be considered by most as being subtle, but to the extent that there was a preference in terms of sound and imaging quality, the votes favored having the side walls left in a reflective state. In mono listening, the voting definitely favored having the side walls reflective."

Perceptual Effects of Room Reflections

Perceptual Effects of Room Reflections By Amir Majidimehr [Note: This article was originally published in the Widescreen Review Magazine, titled "it is not simple!"] When Gary Reber asked me to write an article for the 20th anniversary of Widescreen Review magazine I was stumped at first...

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