[Ethan Winer]

I have read that that a completely dead room is not appropriate but at the same time, any reflections in the listening room are to be avoided.  Are these not mutually exclusive goals?  Are we talking about primary reflections only?

As I see it, the problem with a totally dead room is not so much how it makes music from loudspeakers sound. Rather, it makes conversation and everything else you do in the room sound unnatural.

--Ethan

[John Casler]

I have read that that a completely dead room is not appropriate but at the same time, any reflections in the listening room are to be avoided.  Are these not mutually exclusive goals?  Are we talking about primary reflections only?

As I see it, the problem with a totally dead room is not so much how it makes music from loudspeakers sound. Rather, it makes conversation and everything else you do in the room sound unnatural.

--Ethan

I agree.

If the sound you hear does not reach your ears in a straight line from the speaker driver, it is distortion to the recorded signal.

Using room sound to suit a preference is simply creating sound to a sonic preference, of which there is nothing wrong. 

[darrenyeats]

If the sound you hear does not reach your ears in a straight line from the speaker driver, it is distortion to the recorded signal.

John, I have to face the unfortunate possibility this is true.

I would like to share some additional thoughts. In baseball you can get a higher score by hitting a home run every time...in theory. However, trying to do so...and falling short of absolutely perfect execution...can work out worse than trying an altogether different strategy.

Having an anechoic chamber is great. But if you achieve anechoic except there's 20% reflectivity in the treble, then you've illuminated the room with an unnatural response. Wouldn't it be better to illuminuate the room with 30% reflectivity but broadband? That's a lot more reflectivity in total...but a more natural response. It doesn't follow that the aim, in the absence of perfection, is to travel unblinking a straight line towards perfection. Perhaps the solutions need to be proportionate, nuanced and perhaps even creative given the challenges of real domestic environments and the peculiarities of human hearing.
Darren

[youngho]

There is an axiom by Voltaire often quoted by surgeons as "The perfect is the enemy of the good," which I've also heard stated as "The enemy of a good plan is the dream of a perfect one." Sometimes in trying to make things better, you can screw them up. I'm sure examples will spring readily to mind.

"If the sound you hear does not reach your ears in a straight line from the speaker driver, it is distortion to the recorded signal." That's why headphones are the best form of sound reproduction. Oh, wait...

(edit) headphones have limitations, too...

[Daygloworange]

I would encourage anyone who wants to really maximize the full potential of 2 channel playback, to read books on recording engineering. The fundamentals are not that hard, and often, all it takes is a visual illustration to correctly grasp what is going on in audio reproduction.

Of course the lower the frequency the more the tendency of a sound to spread in all directions, whether natural or reproduced.

Now the higher the frequency of a sound, the more stark the character of its directionality. When I think of the highest frequency sounds in music I think cymbals first (and triangle second). This sound spreads in all directions. This instrument is (a) high frequency therefore directionality is very important in reproduction and (b) disperses in all directions in real life. This doesn't strengthen the argument for box speakers - cymbals are kind of important.

Exactly.  And that's part of why reflections can be so damaging.  The reflected sound is not of the same response distribution as the original sound so it not only smears things in time but also mucks up (technical term) the frequency balance.

I used to see it that way, but not anymore. You can view the sound that arrives at your ears two ways.

darrenyeats,

In a theoritically perfect (sic) 2 channel recording, you would use 2 microphone diaphragms. They would be spaced 6" to 8" apart and angled to match the angle of incidence of a human's ear canals, and with a non reflective divider between them to eliminate channel crosstalk(it actually exists, it's called a binaural dummy head mic). I'll use this 2 mic method to illustrate my example.

The microphone diaphrams mimic the tympanic membranes in your ears. You have a left ear, and a right ear. You have 2 mics. 2 independant channels of information. The microphones are mono sources, so are your ears. You ears work independently of each other. It's your brain that extrapolates the differences between the two independant channels of information from your ears.

Mic's are aimed at a sound source in an effort to replicated the distance and different time arrivals to each ear of a listener. Speakers are positioned to reverse that. Technically, the best set up would be to have a large room with an absorbant dividing wall down the center (floor to ceiling) of the room, up to your listening position, so you don't have any channel crosstalk (sound arriving at your right ear from the left speaker, and sound arriving at your left ear from the right speaker).

This is very similar to binaural recordings, examples of which can be frighteningly realistic sounding, particularly with headphones.

Yes, a cymbal radiates sound(evenly) in all directions (most, if not all sound sources do, but not evenly in all frequencies), and causes reflections in the room that it happens to be in. The direct and indirect sounds arrive at your ears in an amplitude ratio, and time domain ratio, and frequency ratios.

Your ears pickup the direct sound, and the reflected sounds.

Microphones mimic what your ears do in that same situation. The two independant channels of L/R info from the mic's are reproduced with 2 L/R speakers. If you do not introduce any added reflections, eliminate channel crosstalk, and have a very linear high resolution playback system, you will have avery convincing soundstage of the live event.

The second way of viewing it is not how it looks in a scope, but how it is perceived by a human listener.

In a perfect (sic) 2 (mic) channel recording, you are actually reproducing what is happening at the interface between the source of the sounds, and your ears.

Now human listeners have a lot of in-built 'DSP' for dealing with all kinds of crap that happens with real sounds and real spaces. We are filtering reflections all the time in real life.

The brain is fed an input from the sounds your ears capture. Your ears don't filter anything. Microphones are designed to capture sounds like ears do.

An audio system's job is to relay what the microphones (in place of your ears) picked up. If the audio system were perfectly linear, what you would be hearing if your earswere in the place of the microphones (which happen to be there in place of your ears).

that is not what microphones and stereo speakers do. Instead they record the effect of reflections at the microphone position in the performance space, then re-broadcast the effect from just two points in the listening space. The perception of the listening space is an illusion, not a literal reconstruction.

I agree with this. All the ambience and reverb etc you want was already captured by the microphones. (Or for pop music, added artificially by the engineers.) The job of loudspeakers is to reproduce that cleanly without interference from early reflections in the much smaller room the speakers are in. I'm sure we all agree that a concert recording heard through headphones can sound huge. So that alone proves that reflections in the listening room are not needed for a realistic sounding and satisfying experience.

--Ethan

I agree with Ethan, and I've said the same thing many times. You want to eliminate any reflections in your listening space. The problem is not only reflections, but room gain and peaks and nulls in FR.

In fact darrenyeats, the recording in the example I give is a perfect reconstruction of what a listener's ears are capturing.

Exactly.  And that's part of why reflections can be so damaging.  The reflected sound is not of the same response distribution as the original sound so it not only smears things in time but also mucks up (technical term) the frequency balance.

Bryan

I agree with Brian here as well. What an untreated listening room is doing is generating additional reflections to the listeners ears that were not present at the capture of the live event. This is corrupting the audio. Distortion.

 Ethan, Brian and I all have experience with the science of recording music. We all have had spent time learning and studying how recordings are done.

I won't speak for either Brian or Ethan, but I'm sure that they would agree with me that a room without walls, a ceiling, or a floor would be the best listening room.

In lieu of that, if you want to hear what was really captured by the microphones, as faithfully as possible, room treatments are necessary.

Cheers

[John Casler]

I won't speak for either Brian or Ethan, but I'm sure that they would agree with me that a room without walls, a ceiling, or a floor would be the best listening room.

In lieu of that, if you want to hear what was really captured by the microphones, as faithfully as possible, room treatments are necessary.

Cheers

Dayglo,

I have been on that train for many years.

If you're ever in LA, you need to call me (if you have an hour or two to kill)

[woodsyi]

I won't speak for either Brian or Ethan, but I'm sure that they would agree with me that a room without walls, a ceiling, or a floor would be the best listening room.

In lieu of that, if you want to hear what was really captured by the microphones, as faithfully as possible, room treatments are necessary.

Cheers

Dayglo,

I have been on that train for many years.

If you're ever in LA, you need to call me (if you have an hour or two to kill)

And you shall be shrouded in John's throne! 

[Daygloworange]

John,

Sorry man, I forgot to mention that you also said the same thing.

I won't speak for either Brian or Ethan, but I'm sure that they would agree with me that a room without walls, a ceiling, or a floor would be the best listening room.

In lieu of that, if you want to hear what was really captured by the microphones, as faithfully as possible, room treatments are necessary.

Cheers

Dayglo,

I have been on that train for many years.

If you're ever in LA, you need to call me (if you have an hour or two to kill)

There's always RMAF this year. 

Cheers

[John Casler]

I won't speak for either Brian or Ethan, but I'm sure that they would agree with me that a room without walls, a ceiling, or a floor would be the best listening room.

In lieu of that, if you want to hear what was really captured by the microphones, as faithfully as possible, room treatments are necessary.

Cheers

Dayglo,

I have been on that train for many years.

If you're ever in LA, you need to call me (if you have an hour or two to kill)

And you shall be shrouded in John's throne! 

Hi Woodsyi,

No longer hanging acoustic treatment.  Now it is a fully enclosed "Listening Chamber" open only to the front.

If its on the recording you hear it here.  If its not...you don't.

Not quite anechoic, but it is very close to "headphones with precision imaging and HUGE Soundstage. 

I have also used the Center Divider, but with the limited dispersion of the planars I don't get a lot of crosstalk (that one can notice)

But it could not be done in a non-dedicated room, and the reality of the sonics is not for everyone.

One thing I get very little if any mid or HF reflection from the rear wall.

[darrenyeats]

In a theoritically perfect (sic) 2 channel recording, you would use 2 microphone diaphragms. They would be spaced 6" to 8" apart and angled to match the angle of incidence of a human's ear canals, and with a non reflective divider between them to eliminate channel crosstalk(it actually exists, it's called a binaural dummy head mic). I'll use this 2 mic method to illustrate my example.

Dayglow,
Thanks for your post. I agree with most of the technical stuff actually. BTW the comments I made about the 're-constructive illusion' of two channel stereo were more about wondering aloud about how the Orions work in an untreated room. Because, to my ears, they do. I was musing over whether the re-broadcast reflections could somehow NOT be irretrievably mangled with the listening room reflections thereby allowing the brain to say filter the most 'normal' set of reflections deeper into the subconscious. Just an idea, not saying this is how it works. I am just searching for an explanation for a personal experience. No this isn't the way to re-create the perfect original event in theory.

I have also used the Center Divider
<snip>
But it could not be done in a non-dedicated room

This is where I differ from John and Dayglow. I am aiming for the best result in a normal domestic environment - which I stated in my last post. For example, one of the things I prize is the avoidance of a sweet spot. I want all my guests - and I do host occasional music nights with fellow music lovers, not audiophiles - to enjoy the music. Another thing the Orion does well, and another which is more difficult with 'room-sized headphones'.

Thank you for your explanations which I found educational. However I remain with Youngho and I appreciate his Voltaire quote "The perfect is the enemy of the good." That sums it up - in terms of my frame of reference which is a little different to yours.
Darren

[youngho]

Daygloworange, Bryan, and Ethan, I wondered if you could comment on the head related transfer function and the effects of the absence of dummy ear molds in simple 2 mic stereo recordings. Also, in your theoretically perfect 2 channel recording, how important is it to closely model the actual listener's own head size and ear shape? For example, I have a large head (unfortunately, not a large brain). I have a friend with a much smaller head (he's much smarter) but his ears protrude much more.

How do binaural recordings sound on a non-optimized loudspeaker setup? How well does a binaural optimized loudspeaker setup work for non-binaural recordings? How extensive should room treatments be when the inputs of multiple microphones are mixed for home playback, and what kinds of assumptions, if any, do recording engineers make about their listeners' rooms? For example, I had read about the use of a certain Yamaha monitor to emulate non-audiophile speakers.

What do you think of the Kimber IsoMike approach to recordings? Is this a nearly perfect method of non-binaural recording, in your opinion?

Lastly, do you mind recommending a specific book for those of us with no background and a casual interest? Thanks!

[bpape]

I can't comment on the binaural.  I'm not versed in the technicalities of it - sorry.  I was more referring to a standard 2 mic setup.

Bryan

[darrenyeats]

Yes, a cymbal radiates sound(evenly) in all directions (most, if not all sound sources do, but not evenly in all frequencies), and causes reflections in the room that it happens to be in. The direct and indirect sounds arrive at your ears in an amplitude ratio, and time domain ratio, and frequency ratios.

Your ears pickup the direct sound, and the reflected sounds.

Microphones mimic what your ears do in that same situation. The two independant channels of L/R info from the mic's are reproduced with 2 L/R speakers. If you do not introduce any added reflections, eliminate channel crosstalk, and have a very linear high resolution playback system, you will have avery convincing soundstage of the live event.

I can understand how listening to a binaural recording on headphones is like that. Nothing I'd disagree with.

The second way of viewing it is not how it looks in a scope, but how it is perceived by a human listener.

In a perfect (sic) 2 (mic) channel recording, you are actually reproducing what is happening at the interface between the source of the sounds, and your ears.

Now human listeners have a lot of in-built 'DSP' for dealing with all kinds of crap that happens with real sounds and real spaces. We are filtering reflections all the time in real life.

The brain is fed an input from the sounds your ears capture. Your ears don't filter anything. Microphones are designed to capture sounds like ears do.

An audio system's job is to relay what the microphones (in place of your ears) picked up. If the audio system were perfectly linear, what you would be hearing if your earswere in the place of the microphones (which happen to be there in place of your ears).

I think you misunderstood my point. Yes the microphone picks up what ears would have heard in the original space. The listeners ears pick up the sound re-broadcast from the loudspeakers-or-headphone plus any listening room reflections (if applicable). My question was about how the listener's brain might interpret the sounds in such a fashion as to filter out just the listening room reflections from the experience. As stated I've experienced this illusion and am looking for an explanation. (Of course, it's possible I heard just what I wanted to hear, a personal illusion: it wasn't a DBT or well controlled experiment. I could leave it there but I feel I must know if this is a consistent, repeatable illusion, and if so why it works. )

If you don't think this is possible, then that is a different matter to your comments (which I even happen to agree with).

In fact darrenyeats, the recording in the example I give is a perfect reconstruction of what a listener's ears are capturing.

Except, if you're not wearing headphones but listening through speakers, you are listening through two head related transfer functions. First the dummy head at the mics, and second your own. Have I got that right?
Darren

[Ethan Winer]

Daygloworange, Bryan, and Ethan, I wondered if you could comment on the head related transfer function and the effects of the absence of dummy ear molds in simple 2 mic stereo recordings.

I too have no knowledge of this worthy of sharing.

--Ethan

[Daygloworange]

I think you misunderstood my point.  Yes the microphone picks up what ears would have heard in the original space. The listeners ears pick up the sound re-broadcast from the loudspeakers-or-headphone plus any listening room reflections (if applicable). My question was about how the listener's brain might interpret the sounds in such a fashion as to filter out just the listening room reflections from the experience. As stated I've experienced this illusion and am looking for an explanation. (Of course, it's possible I heard just what I wanted to hear, a personal illusion: it wasn't a DBT or well controlled experiment. I could leave it there but I feel I must know if this is a consistent, repeatable illusion, and if so why it works. )

If you don't think this is possible, then that is a different matter to your comments (which I even happen to agree with).

No, I don't think your brain can filter out reflections. Then we would filter out the reflections that make up the diffused sound of a live event as well.

We can focus our consciousness, but I don't think our hearing is capable of filtering out peripheral sounds.

I think it's like asking if we can filter out fog when looking out into the distance. Our eyes can't filter out the fog.

Except, if you're not wearing headphones but listening through speakers, you are listening through two head related transfer functions. First the dummy head at the mics, and second your own. Have I got that right?

In a listening room that's void of reflections and crosstalk, listening to speakers would be the same thing.

What do you think of the Kimber IsoMike approach to recordings? Is this a nearly perfect method of non-binaural recording, in your opinion?

I listened to about 10 minutes worth of IsoMike recordings at RMAF. What I heard was no more impressive than a 5.1 movie soundtrack. I was listening to an orchestra piece and there were marching snares being played behind me to the left. I don't call that realism. I call it atrificial.

Daygloworange, Bryan, and Ethan, I wondered if you could comment on the head related transfer function and the effects of the absence of dummy ear molds in simple 2 mic stereo recordings. Also, in your theoretically perfect 2 channel recording, how important is it to closely model the actual listener's own head size and ear shape? For example, I have a large head (unfortunately, not a large brain). I have a friend with a much smaller head (he's much smarter) but his ears protrude much more.

Ear molds are there to mimic any nonlinearites of relections at the entrance to the ear canal that would affect the FR of the human ear due to amplitude variations of a given sound event. They're just trying to mimic human ears.

How close do we have to model the actual listeners head? The space between your ears, and someone else's would be quite small. The difference in fractions of milliseconds between the 2 channels would hardly be worth noting IMO.

How do binaural recordings sound on a non-optimized loudspeaker setup?

Well, they simply won't sound up to potential.

Cheers

[youngho]

Bryan, Ethan, Daygloworange, thanks for your time.

The reason I asked specifically about the dummy head model and ear molds is that I had heard that the head related transfer function was extraordinarily dependent on specific characteristics of the listener, essentially unique to each individual, but it's good to hear that HRTFs are similar enough that this doesn't seem to be an issue for recordings. Psychoacoustics is far beyond my ken.

I had also been under the impression that the shape of the ears contribute to the ability to distinguish between noises that are in front of and behind the listener. Thus, I wondered whether the very act of recording with a simple 2 mic setup, even with a dummy head to introduce an acoustic shadow to reduce crosstalk between the two microphones, especially if ear molds were not present to affect the perceived or recorded frequencies and timing of reflections from fore versus those from aft, might itself necessarily introduce distortion relative to what an actual listener might hear. I had heard that binaural recordings played back over headphones can produce directional cues so that sounds can really seem to come from in front, behind, and even above the listener, rather than the "in the head" experience that nonbinaural recordings usually evoke. I had wondered whether binaural recordings played back over loudspeakers could evoke similar directional cues and whether nonbinaural recordings might require some lateral and rear reflections to evoke the perception of spaciousness, rather having the entire acoustic image coming from the front only, which seemed to be related to the minimal acoustic treatment that Linkwitz and Toole seem to feel are needed for typical living rooms for music reproduction. Is this part of how pseudo-surround sound works, through signal processing to try to "fool" the ear? For 2 channel playback, I wonder whether the preservation of reflections' spectral content allows the ear to perceive lateral and rear reflections differently from signals coming from the front, which I think may partially address one of Darren's questions about whether the brain may be able to process this auditory information differently from the direct signal itself, basically related to why we are able to grossly localize real-world sounds, even in somewhat reflective rooms.

With respect to cross-talk, I know that there had been attempts like the Sonic Holography and MARSS circuits to reduce the amount of crosstalk during playback. I think the MARSS approach also discussed the use of an acoustic baffle down the midline in front of the listener. Just as I haven't heard any binaural recordings, I haven't had the opportunity to hear any two- or four-channel IsoMike recordings myself, so I appreciate hearing about your experience, since the use of the baffle looked like an interesting non-binaural attempt to deal with this at the recording level.

I've learned a lot from reading, thinking, and posting. Thanks to all. Again, if someone might recommend a book on recording for someone like me with no background but a casual interest, I'd be grateful.

(edit) Should have read "I've learned a lot from reading HERE, thinking, and posting."

[Ethan Winer]

Is this part of how pseudo-surround sound works, through signal processing to try to "fool" the ear?

All the pseudo surround stuff I've heard uses phase shift trickery to make things sound like they're coming from outside the width of the left-right speaker width. All the gadgets I've heard sounded phony to me, though I haven't heard them all.

--Ethan

[Daygloworange]

Is this part of how pseudo-surround sound works, through signal processing to try to "fool" the ear?

All the pseudo surround stuff I've heard uses phase shift trickery to make things sound like they're coming from outside the width of the left-right speaker width. All the gadgets I've heard sounded phony to me, though I haven't heard them all.

--Ethan

I agree with Ethan here as well. The synthesized stuff that's out there always sounds like there are phase problems somewhere, in an effort to cancel channel crosstalk. It still doesn't address the harmful room reflections that are being added to the direct sound coming from your speakers and obscuring proper imaging.

Here's a thread where we discussed psychoacoustics, and tested one such surround type technology. The results were not good AFAIC.

http://www.audiocircle.com/index.php?topic=49710.0

The best surround sytems I've heard and empirically experimented with are Q4 based recordings on a quadraphonic style playback system comprised of independant front and rear 2 channel setups.

Cheers

[youngho]

Ack, should have left out that question about the simulated surround. Thanks, though.