What is "Sound Stage?"

[Soundproof]

Tim,

Microphones do not hear direction, unless they are directional (you should ask CIA or the KGB about that, they are specialists at this subject )

I guess it's intended as a joke, but we should be clear that directional microphones don't hear direction, with varying effectiveness they "ignore" sounds from points other than the direction in which they are aimed. At playback, you have absolutely no idea as to which direction they were aimed towards. You're just hearing the sound they registered.

 

[Soundproof]

Bill,

Suppose you have a single mic recording a person speaking moving away, approaching the back wall. Can you tell me if when listening you can get a perception he is moving away, as the his voice balance is changing as the reflected to direct sound is changing while the level is becoming lower - something very different from what you get just fading the level.

Actually, when a person moves away from a microphone in this manner, a number of things happen that affect the character of the acoustical energy reaching the microphone. Bass energy will drop, treble energy will persist more, the general level will drop, treble reflections from the walls will create an acoustic aura around the perceived direct energy - if the person turns around, back facing to the microphone, we will be picking up more of the reflected treble, the bass will drop considerably, and the direct energy will be reduced.

There would be no directional information in any plane to one microphone - but you would perceive the sound source as becoming smaller or larger, thinner or fuller (FR), according to vanishing point perspective.

Acoustic energy characteristics change significantly with distance - if not, then two microphones placed just a few inches apart couldn't register a proper stereo image. Distance in a sound stage is mostly the extent to which the source has fullness, or is lacking in parts, relative to other sources in the soundfield (treble/mid carries farther than bass, for instance).

Kudos to Bill for his lengthy explanation at the bottom of page 25, which should be required info.
I put a good link to IsoMike at the bottom of page 5, as the discussion started taking off.

 

[JackD201]

What he said!

Roger, I wish I could talk about 35mm film. Way before my time and I've never heard it in its native form, just transfers to the very few MLS originals I have. If I did talk about it it would just be regurgitated info

 

[JackD201]

Which, Jack? Raising and lowering the mics, or playing with phase interference effects. If the latter, it has to be subtle, the echos would be attentuated by many 10's of dBs, and should take frequency dependent absorption into account. The closer you could fake the real thing the more significant the results ..

As an aside, googling microphones and "height information", it appears that sound engineers have absolutely no problem with using two mics sitting next to each other pointing at different angles "magically" capturing all the height info you want, but as soon as you use just one mic to do this, all bets are off. It's the first time I understood that mics have blinkers on, anything not coming directly in front of them is completely invisible -- I'm amazed that conference mics work at all ...

Frank

Here's the absolutestly simplest thing you can do. Take a camcorder with stereo capability and walk around the park pointing it whichever way you like. Hook it up to your system and tell me what you hear.

 

[Phelonious Ponk]

I guess it's intended as a joke, but we should be clear that directional microphones don't hear direction, with varying effectiveness they "ignore" sounds from points other than the direction in which they are aimed. At playback, you have absolutely no idea as to which direction they were aimed at. You're just hearing the sound they registered.

I'm beginning to think I"m communicating badly and understanding worse, because I don't think we're clear on this point at all. I think there are people here who are arguing the opposite of this obvious, fundamental truth.

Here, this ended up in the wrong thread. It's really all I have left on the subject:

Let's examine where we're actually disagreeing Jack:

Jack - "You keep talkng about mics and how they don't know stuff. Well a chisel doesn't know stuff but that doesn't stop a sculpture from making things with them."

People here...I don't remember if you have or not, to be honest...keep talking about how mics, because they're directional, are capturing height information. They simply are not. You know this as well as I, A highly directional mic will alter the FR of a signal coming at it from outside of its pattern, but there is nothing about the mic, or anything in the recording or playback chain beyond that mic to interpret that information and place it in a field. Nothing to determine what direction off axis the sound came from. That's all I'm saying about mics.

Jack - "You also keep on using your microphone rant in a mono context when we aren't talking about mono."

I'm pretty sure the only thing I've said about mono is that if we can get a clear vertical image without vertical channels, there wasn't much need to invent stereo in the first place.

-- "You don't need a center channel to get a decently convincing center image out of two spaced loudspeakers so I don't see how you can even say you require a discreet soundsource and a discreet signal to simulate one."

Not sure what the point is here. I agree. But I'm not questioning the ability to get a solid phantom center from stereo. I'm not even questioning the ability to get a detailed pinpoint image - multiple phantom images across a broad stereo field. I'm question the ability to get that same king of solid phantom imagine vertically, with no vertical channels. And that's all I'm questioning. I'm not denying that there is a sense of height, I'm asking how there can be a clearly differentiated vertical image, a solid field of vertical images, when there are no vertical channels.

Jack - "Even Bill has skirted the fact that in certain rooms he's been able to get sound to hover his listener's heads with just two channels. Simulate surround sound as well. That is height. Period."

I'll acknowledge it as well. I think these things are parlor tricks, personally. Fun, but not all that useful, but I've heard them too. and I've heard "tall" sound stage. And I've heard that vague sense of a vertical field you can get from some speakers/rooms when certain frequencies seem to divide into vertical layers with the response of the drivers. But there are several folks in this thread who are describing something well beyond that. They're describing, one more time -- a clearly differentiated vertical image; phantoms from top to bottom, imaging, like we get from left to right without the hardware to create that image.

I don't know how to make myself any clearer. That, and that alone, is what I firmly believe is not happening. If that's what you hear, then yes, we disagree. And now there's nothing more I can really say either.

Tim

 

[Soundproof]

As this thread is about the sound stage, and we're discussing what Mono mikes can "hear", the Duke Ellington 1956 concert should be of interest. I have the original mono release, which was not the real concert, as Duke and the band did an extra recording session to fix errors.

It took many years before we got "the real thing", and then only because a separate mono recording of the actual concert was found in the Library of Congress. Columbia did one recording and Voice of America did the one stored at LoC. Both had their microphones adequately placed, but with such separation that Phil Schaap was able to do the indredible work required to merge the two mono signals into a stereo version.

It's worth it to compare the information in the original mono release, and what happens when you listen to the found stereo version that Schaap and his crew created. (They were able to digitally time-synchronize the two master tapes, to make the information blend as a stereo image - an incredible feat, which also resulted in a very enjoyable sound stage).

As I'm fortunate enough to have a NM of the original mono release, and can compare with the stereo-release, I can also make a number of fairly competent assessments as to what constitutes the illusion of soundstage, from this example alone, and would recommend the same journey to others interested in the topic.

http://jazztimes.com/articles/10496-ellington-at-newport-1956-complete-duke-ellington

 

[bblue]

Bill, are you 100% certain about this?

Yes.

 

[Phelonious Ponk]

As an aside, googling microphones and "height information", it appears that sound engineers have absolutely no problem with using two mics sitting next to each other pointing at different angles "magically" capturing all the height info you want

Can't find it. Got a link?

Tim

 

[bblue]

Bill,

Suppose you have a single mic recording a person speaking moving away, approaching the back wall. Can you tell me if when listening you can get a perception he is moving away, as the his voice balance is changing as the reflected to direct sound is changing while the level is becoming lower - something very different from what you get just fading the level.

Yes, you can. But the way you can tell is by the ratio of direct sound and reverberant sound that the mic picks up. It does hear reverberations and reflections, but they become mixed together at the point where they vibrate the mic diaphragm. The more reverberation, the more distance you perceive. It's pretty much the same as listening with one ear. Listening with two ears you can also localize position, much the same as with two mics -- when the two mics are played back as two stereo channels you can also localize in the lateral plane.

Also, the characteristics of the mic enter in to this. An omni directional mic will consistently pick up more reverberation than others since it 'hears' all directions simultaneously. Whereas a Cardiod or uni-directional mic hears (for the most part) from the direction to which they are optimized. A shotgun mic uses a tuned chamber to 'hear' only sounds at longer distances. But no matter how the mic is designed, all sound that each hears is summed into one diaphragm and one resulting signal.

--Bill

 

[bblue]

Hello, Bill. Thank you for caring enough to actually try this and not just discount the entire discussion or other people's point of view/observations based solely upon what you already know or have heard. To me, that's impressive. Thanks again. You had mentioned in the above quote, the "pressure" between channels and between LF and HF transducers. Yeah, I noticed a lot of it as well. Makes the image characteristics and sound change for the worse but as you mentioned, the image nonetheless does move up.


OK.


Now think about what you just said and go back and read above where I replied "OK". Don't the two contradict each other? Nothing else changed in your rig with the exception of the recording [the LEDR test], yet you say it has nothing to do with the original recording. It was the recording that produced the height, no? What else in your rig/room could have produced it if the recording was the only thing that changed?

The LEDR test was based on a manufactured (computer generated) sound of a particular type, designed to create phase and level movement that make that sound seem like it is moving vertically. It is not a sound or combination of events that happens in a live environment with any predictability.

My reference to 'original recording' was meant to imply a music recording of the type we normally would listen to, recorded with stereo mics (two channel) and passed along to the output L & R channels for playback. The type that some claim has true height information embedded in the L & R signals.

The manufactured recording produced some vertical movement, whereas on the same system, no pre-recorded music event produces height information. What height that seems to be portrayed is only by virtue of the height of the speaker transducers and the frequency range they cover.

--Bill

 

[bblue]

As an aside, googling microphones and "height information", it appears that sound engineers have absolutely no problem with using two mics sitting next to each other pointing at different angles "magically" capturing all the height info you want, but as soon as you use just one mic to do this, all bets are off. It's the first time I understood that mics have blinkers on, anything not coming directly in front of them is completely invisible -- I'm amazed that conference mics work at all ...

Emphasis is mine.

Frank, I believe you misunderstand the reason two mics might be side by side and pointing different directions. It's NOT for gathering height information. It can be for one of two reasons.

1. If the output of each mic is captured separately (two channel) DISTANCE information is being captured, or there is something unique in each direction that needs focus during mixing.

2. If the outputs of the mics are mixed together you get more presence of whatever is being pointed at by each of the mics, at the possible expense of some phase shift for anything captured off the back of each mic.

This is commonly done when close micing multiple elements of drum kits, but can be done for a variety of reasons. If they are used to record the distance between two points, it won't matter what direction they are pointed, left right, up down, diagonally from upper left to lower right, when played back on a stereo system, that distance will appear to be lateral.

It won't necessarily be realistic, but can be an interesting effect, resulting in some additional but inaccurate depth within the area of interest.

--Bill

 

[Robh3606]

Food for thought

http://en.wikipedia.org/wiki/Soundfield_microphone

Rob

 

[FrantzM]

The more I read this thread the more I think that the best soundstage possible with the currently available technologies would be that brought by (at least) 9 channel surround system with the usual L, C, R, two front mounted height information Channels, 2 Side Channels and Rear Channels... Blu Ray has the Capacity to carry all these at Hi-Rez .. . Whether or not we will ever see such or if audiophiles will ever accept it is open to debate but the present discussion more than any other points toward the very serious limitation of our present 2-channel "Stereo".

 

[treitz3]

And what bothers me, Greg is that someone might read what you say and conclude that there is something desperately wrong with their listening experience, and believe that they can get a four channel horizontal and vertical image from a two channel stereo system, if only they spend enough money.

[The highlights were added by me] To which I responded...

Tim, all due respect but not one person in this discussion has said this. Not one.

I clearly see that folks here have mentioned that they hear vertical information. What no one had mentioned in the thread, was the relation to how much money had to be spent in order to achieve it. That was my point. No biggie, in the whole grand scheme of things, it's really unimportant. That said, it was misleading as nobody had mentioned money as being part of the equation of height in a reproduction.

Well, actually, here is the comment from Greg, which started the exchange that ended above:

...planar speakers have height almost exact to there own physical dimensions. Yet the height of the individual instrument being played can mimic the real thing.

No reference to the price being a factor.

If they can mimic the position of the instruments being played, that is imaging. If they can do it vertically, then they can do, without up/down channels and up/down speakers what a lot of decent stereos/rooms, with the appropriate left/right speakers/channels struggle to accomplish with any precision horizontally. And Greg is not the only one in this thread to have described precise vertical imaging. Have they put it the way I did? No. But I think you and I are discussing semantics at this point.

Actually, we are discussing a rather interesting and engaging topic IMO. I'm learning things as I go and I hope others are as well. Personally, this is one of the most interesting conversations that I have been involved with. Basically, I'd like to understand why I'm hearing precise vertical imaging [on some recordings] when the "facts" and "truth" by some very knowledgeable folks say that it can not be achieved. Hence, the engagement and active participation not only by me, but many others.

 

[microstrip]

I guess it's intended as a joke, but we should be clear that directional microphones don't hear direction, with varying effectiveness they "ignore" sounds from points other than the direction in which they are aimed. At playback, you have absolutely no idea as to which direction they were aimed towards. You're just hearing the sound they registered.

Surely it was joke. Next time I will append a picture - may be this way people will have no doubts.

But, if for example, you are in a zoo you know well, and you listen to a snake rattle far away superimposed with the voice you are spying, you can know that the direction the microphone was pointing was not the bird nests in the trees. Surely if do not know the zoo you risk that you are in a place where snakes live in trees and bird do not fly .

My point is that height information is a mixed situation - technical manipulation and small sound clues. Both contribute to the illusion of relative height, not very accurate and reliable, but enough to increase listening pleasure and cause debates in WBF.

Systems and our brain must deal with this information appropriately to be effective.

 

[NorthStar]

The more I read this thread the more I think that the best soundstage possible with the currently available technologies would be that brought by (at least) 9 channel surround system with the usual L, C, R, two front mounted height information Channels, 2 Side Channels and Rear Channels... Blu Ray has the Capacity to carry all these at Hi-Rez .. . Whether or not we will ever see such or if audiophiles will ever accept it is open to debate but the present discussion more than any other points toward the very serious limitation of our present 2-channel "Stereo".

Yes Frantz, I mainly agree with you on this; but surround sound recordings are not yet there IMHO.
Few multichannel ones on SACD are pretty good though and they do a realistic job of conveying a Concert hall. Bring more of these, then you'll see more people adding more speakers to their two-channel stereo rig.
But Hybrid Multichannel SACDs are less available than two-channel stereo albums (LPs).

...And I still love Stereo. Its magic soundstage and imaging from just two speakers.
Three channels, with a center one? ... If well positioned, yes.

* 'Bout a 3-channel setup arranged in a triangle type of shape, with the center speaker above his two flankers, and aimed at the listener?
You can then have a soundstage also in the vertical plane to add considerable height.
But are our ears better at decipering information in the horizontal plane than the vertical one?

I wonder if some music recording engineers have experimented with that ...
But I do know it sounds excellent when positioned so (I did arrange my front soundstage's three speakers that way in the past, and was totally amazed with the level of realistic presence; and even when standing up)!
The clarity, the integration, the complete front soundstage fulfillment from the center speaker with its two flankers was unmistakable.

 

[Phelonious Ponk]

[The highlights were added by me] To which I responded...


I clearly see that folks here have mentioned that they hear vertical information. What no one had mentioned in the thread, was the relation to how much money had to be spent in order to achieve it. That was my point. No biggie, in the whole grand scheme of things, it's really unimportant. That said, it was misleading as nobody had mentioned money as being part of the equation of height in a reproduction.



No reference to the price being a factor.


Actually, we are discussing a rather interesting and engaging topic IMO. I'm learning things as I go and I hope others are as well. Personally, this is one of the most interesting conversations that I have been involved with. Basically, I'd like to understand why I'm hearing precise vertical imaging [on some recordings] when the "facts" and "truth" by some very knowledgeable folks say that it can not be achieved. Hence, the engagement and active participation not only by me, but many others.

Point well taken. The price of achieving a vertical image, or even the notion that it is a particularly expensive thing to achieve had not been mentioned. I know it always goes there, though. If in no other way it eventually comes down to the idea that those who don't "hear" some phenomenon or another are missing it because their systems lack the quality, not because, using this example, there is no electro-mechanical means of achieving what is being "heard." Give it long enough, it will get there. Review. It has probably already been there. But specific mention of price? You're absolutely right. I was the first one to bring that up. My bad.

Tim

 

[Phelonious Ponk]

While I enjoy everything the soundstage can give, for me in particular, the center channel fill information (created in my brain) lacks energy and so if and when I purchase new speakers, I will get a third center channel.

What signal will you send to this third channel, Tom?

Tim

 

[Soundproof]

Well, there was this regularly proposed explanation:

For someone to say there is no such thing as image height tells me that they've never heard a good high-end speaker or system

Price wasn't mentioned, but it was implied, and by quite an authority on the subject of price in hifi.

Let's not get distracted by that, though. I agree it is a fine thread, and also agree that we're on the verge of a revolution in high-fidelity verisimilitude, through the possibilities offered by multi-channel playback.
To that point, why place the speakers around ourselves when they could all (say seven) be in front of us, where we are used to performances coming from?

 

[Phelonious Ponk]

Well, there was this regularly proposed explanation:



Price wasn't mentioned, but it is implied, and by quite an authority on the subject of price in hifi.

Let's not get distracted by that, though. I agree it is a fine thread, and also agree that we're on the verge of a revolution in high-fidelity verisimilitude, through the possibilities offered by multi-channel playback.
To that point, why place the speakers around ourselves when they could all (say seven) be in front of us, where we are used to performances coming from?

Now we're talking. Get some real height information going on and compare. That would be instructive. I'd go for eight, though, not seven; high/low L/C/R and two subs. A lot could be done with that. How do you see the seven being configured, Soundproof?

Tim