Surround Sound vs 2 channel stereo

[skeptic]

The original claim for stereo was that it would create the audible illusion of anything up to an entire orchestra spread across an imaginary stage in your home. Having heard plenty of live orchestras across real stages and plenty of stereo sound systems in my time, all I can say is that the reality of stereo sound always seems to fall far short of the claim even for this limited goal. When people start talking about claims that even exceed this unachievable goal such as the ability to reproduce the acoustics of the live performance, IMO, they are dealing in fantasies. Perhaps they have never really attended live performances in real concert halls. At least not to listen to music that wasn't so deafening that you could actually hear it.

A center channel identical to the left and right and carefully adjusted can eliminate the "hole in the middle." It is an improvement over 2 channels but it is not a complete cure for the problem of localizing individual instruments. As with most ideas that actually work, serious audiophiles have rejected it. I have not seen a photograph or description of even one audiophile's sound system for the purpose of music reproduction which shows the installation of a third center channel.

[maxg]

You must get the good seats at these live concerts you go to! Try listening from the God's sometime!!! In most concert halls you would defniitely prefer your stereo - even with Bose speakers!!

Another thing to bear in mind. Even if you could shoehorn an orchestra into your living room it still wouldnt sound the way it does as the concert hall - so stop blaming the stereo and move into a house with its own concert hall!! Then you could try the stereo in there and see how it does.

[skeptic]

I don't know what you are talking about. If you prefer the sound of recordings to the sound of live music, that's your business. The stated purpose of high fidelity sound, at least once upon a time, was to reproduce the sound of live performances. When people refer to "accuracy" that is what we presume they are talking about.

" Try listening from the God's sometime!!! " What does that mean? Are you refering to the back row of the last balcony? If you are saying the sound there isn't usually very loud, you are right. Quality of sound is far more important than quantity. Of course front row center has its disadvantages too. Not only can the sound be very loud (for people with hearing of normal unimpaired sensitivity) but you don't hear as much of the hall acoustics either. Critics are given the best seats which are reserved for them usually in Row "K" in many halls. It is the optimal balance between direct and reverberant sound for most listeners. Fortunately most people don't know that so if you can spring for orchestra seats that's the place to be or as close to it as possible.

No home sound system can even begin to reproduce the wonderful sound you hear live in a fine concert hall. The state of the art is far too primitive for that at this stage. At the rate the industry is progressing, that technology will never be developed. If it ever does arrive, it will come with a bang, not a wimper and not with more incremental improvements to the existing paradymes.

[maxg]

I don't know what you are talking about. If you prefer the sound of recordings to the sound of live music, that's your business. The stated purpose of high fidelity sound, at least once upon a time, was to reproduce the sound of live performances. When people refer to "accuracy" that is what we presume they are talking about.

" Try listening from the God's sometime!!! " What does that mean? Are you refering to the back row of the last balcony? If you are saying the sound there isn't usually very loud, you are right. Quality of sound is far more important than quantity. Of course front row center has its disadvantages too. Not only can the sound be very loud (for people with hearing of normal unimpaired sensitivity) but you don't hear as much of the hall acoustics either. Critics are given the best seats which are reserved for them usually in Row "K" in many halls. It is the optimal balance between direct and reverberant sound for most listeners. Fortunately most people don't know that so if you can spring for orchestra seats that's the place to be or as close to it as possible.

No home sound system can even begin to reproduce the wonderful sound you hear live in a fine concert hall. The state of the art is far too primitive for that at this stage. At the rate the industry is progressing, that technology will never be developed. If it ever does arrive, it will come with a bang, not a wimper and not with more incremental improvements to the existing paradymes.

You think the quality of the sound in the last row of the last balcony is good? Well I guess it depends on where you go to listen. In my experience it very rarely is even vaguely acceptable - and not loud is the understatement of the month! I find myself risking death leaning forwards as far as possible desperately trying to catch faint indications of the sounds of the instruments.

Defnitely agree with around row K for the best sound (assuming you number as we do - A at the front). Actually anything between rows 5 and 15 will do for me (E to ..what P? I think). Nothing compares to the sound in those seats - in the centre of course.

[skeptic]

"assuming you number as we do - A at the front"

Whenever someone uses the word "whilst" it's a clue to me that they are from Britain.

We usually start with row A and proceed through the alphabet just as you do. But we hold our forks and knifes in opposite hands you use and we drive on the other side of the road. Cricket is only an insect and the only bonnets are worn on women's heads. Sometimes with bees in them.

Tally HOOOOOOOOOO! (bloody good show old chap, I say ----that's from watching old Nigel Bruce black and white flicks on the telly.)

[maxg]

From Britain correct. But now in Greece.

PS - No-one has actually spoken like that since about 1952....

[skeptic]

The BBC asked recently on its web site where the 2012 Olympics should be held. I suggested Athens. By then all of the facilities and the sporting venues will be done.

[WmAx]

No home sound system can even begin to reproduce the wonderful sound you hear live in a fine concert hall.

This is a difficult issue to approach. Unlike with cables, a direct comparision of any technology to the actual event is extremely difficult. FOr example, it is simple to perform an ABX or DBT test on two cables. It is not so easy to compare a sound reproduction system located in a normal size room directly to the acoustic sound of a concert hall. Memory, time and externally influential factors are going to play a roll in what you think you hear as you compare one to the other. The best (practical)approach is to systematically deduct individual phenomena and what is required, which is what is done in labs. As far as general people and/or audiophiles trying to actually compare if a speaker sounds real........ I don't know how this could possibly be done reliably. Unfortunately, I only see that one could judge on a purely subjective level, in any normal circumstance. This opens a big door: people are then free to express their feelings, which do not have to be based in reality. For example, John Doe could llisten to stereo X and it might remind him so strongly of live sound/event, so much so, that he thinks it sounds 'real'. It might not(it can't) actually produce the same soundfield as a live event, but it may be possile that a certain combination of external effects, phsycholigically along with certain acousic phenomena may have been able to fool John Doe's perceptions?

Let me give my perspective: I have heard many stereo systems; while some had certain properties that had some 'live' sound properties in a limited sense, only 1 sounded real too me(percieved) in every sense, and that was limited to a narrow selection of specific recordings. I do specifically go to live performances and recitals and close my eyes and listen in order to have a better idea of what live sound 'sounds' like, FYI. I still percieved one specific set up as sounding real. But, this may not nescarrily apply to anyone else? You might percieve it as exactly the opposite(non-real). I could have been under hypnosis, been heavily biased, etc.. So what I "really" heard is not important; only that in some cases I have percieved a certain thing. Even in the event a stereeo does sound real in limited circumstances, it is not a good solution IMO. Why? I've heard one realistic sounding stereo in 10 years; and that was with specific recordings only and only in a narrow sitting range(could not move more then about 6 inches left or right, or the illusion was shattered). That is not the definition of practical technology, IMO. MOre of a random hit and miss game. Even if one could pull this off reliably, you are still faced with the extremely limited seatig position. Unacceptable. A radical change and development, it seems, is needed in order to produce a sound reproduction system that can RELIABLY produce realistic sound. It should be noted that a strict, standardized recording/mastering process woudl have to be adopted by the music industry if reliable reproduction was to be achieved.

An informative paper on the general development/state of reproduction systems is availabel from harmon.com:

http://www.harman.com/wp/index.jsp?articleId=132

-Chris

[Sir Terrence the Terrible]

Both methods are unsatisfactory for reproduction of many kinds of serious music, especially much classical music.

Skeptic;

You really enjoy making unquatified blanket statements. Have you every heard of Tomlinson Holmann's 10.2 format? If you have not, I suggest you do. It consists of a left, center, and right front speakers, a left and right surround(dipoles), and center surround, left and right upper side wall speakers, two ceiling speakers, and two subs.

It requires special recordings designed for the format(which is its only drawback), but these recording are so meticulously engineered that the quality is outstanding. The way it is set up, you can get a very clear sonic picture of reflections from sides, rear, upper sides and rear, and ceiling, and what is being projected from the front stage.

While the system cannot map EVERY reflection in a concert hall, the size, height, and sonic signature of the hall can be easily heard. It would take too many speakers to fit in an average room to map every reflection, and that is not really necessary to ascertain the sonic personality of a concert hall.

[skeptic]

ABX tests may be useful in comparing two electronic devices which are similar to see if their differences are detectable. ABX demonstrations were conducted by Acoustic Research in the 1960s and 1970s to play special recordings made in an anechoic environment against live performances in the same location. But the differences between recorded sound in the home and the sound of a live performance at a concert is so overwhelming that ABX tests are not necessary. This is because the acoustics contribute usually from about 90% to 98% of what you hear at a live performance. There is no known way to capture this contribution except to a very slight degree and then many of its most salient aspects are lost. For example the closest approach was binaural sound which is different from stereophonic sound. In this two channel method microphones are placed in the audience where your eardrums would be, sometimes in a dummy's head. This is the sound each of your ears hears. Then the sound is played back through headphones And it works....until you move your head and then the whole sound field turns with it. Your brain immediately comes to the only conclusion possible and that is that the sound is coming from within side your head. This happens because you have recorded two scalar fields, not a vecor field which is what you hear live. The sound including the reflections not only have magnitude, they arrive from distinct directions and your brain knows the difference. Methods using loudspeakers invariably fail not only because they cannot capture the reverberant components alone but because they cannot reproduce the diffuse sound fields fine auditoriums create. If you can hear where the reverb is coming from, the system has failed. What kind of reverberation time are you looking at? At mid frequencies in your home about maybe 0,.2 to 0.4 seconds. In a concert hall about 1.2 to 2.0 seconds. The distribution of energy in space time and the changes to spectral content of the reverb is entirely different affecting the tone, the dynamics, harmonies and dissonnaces they create and even the way the musicians themselves perform. All of this is far beyond the current state of the art with 2 channels, 4 channels, 5.1 channels, or 10.2 channels. There's still a long way to go in this technology and not too many people are actually trying to get there.

[WmAx]

. ABX demonstrations were conducted by Acoustic Research in the 1960s and 1970s to play special recordings made in an anechoic environment against live performances in the same location.

Yes. This, when effective, is only because they are using a pure, recorded signal in mono and playing back as a mono source on a mono speaker and using the room reflections to effect the signal the same as teh live instrument in the room. Similarly, stereo can be used in a very reflective room(auditorium) where the audience is distanced far from the sound source, and having little contribution from the direct soudn soruce. ALternatively, playing back the anechoic recording at a distance that is short relative to the distance from walls or a relatively non reflective environment in stereo, comparing at where room reflections were not signficnat enough to cause differences, can lead to a convincing playback as well of this isolated sound. Comparig to the original source in the same environment, they should sound identical or near-identical in these cases.

But the differences between recorded sound in the home and the sound of a live performance at a concert is so overwhelming that ABX tests are not necessary

Your opinon. Mine too, when based on the vast majority of playback systems. But I'm not going to say this is always true.

.

This is because the acoustics contribute usually from about 90% to 98% of what you hear at a live performance. There is no known way to capture this contribution except to a very slight degree and then many of its most salient aspects are lost. For example the closest approach was binaural sound which is different from stereophonic sound

Yes, I am aware of binaural encoding. An additional fault is that headphone playback lacks lower mid/bass frequency distribution through the air, that is detected inaudibly, via bone conduction.

. Methods using loudspeakers invariably fail not only because they cannot capture the reverberant components alone but because they cannot reproduce the diffuse sound fields fine auditoriums create. If you can hear where the reverb is coming from, the system has failed. What kind of reverberation time are you looking at? At mid frequencies in your home about maybe 0,.2 to 0.4 seconds. In a concert hall about 1.2 to 2.0 seconds

For the intent of hearing, two distinctions need to be realized. The reflection time in the playback room is not the issue(when it is defined within a window tht does not negtively effect sound vs. direct radiated sound - approx. >5ms, <20ms). The refelections in the venue are originated from mono sources(each instruemnt, singer, etc.) where as in a listenig room and playbing back in stereo, the ambient effect is dependant on more then just the RT of the room. The effect that I believe allows the 10.2 system and cerain other systems to come close to reproducing the ambient feild of a venue, perceptibly, is dependant on filling enough of th relative plane with sound, in order to confuse the human auditory system. Two channel systems that can, in some cases can seem like a large reverberant venue, create large effective areas of radiation that confuse the brain - these are full band omnipolar and beveridge lens array setups. In such cases, the broadband reflections from the front and side walls act as virtual sound sources. THe image and ambience is dictated by the source, for example both channels producing an in-phase, equal amplitude signal will produce the stereo image effect, seeming like a defined single source, even though the sound is being heavily reflected orm the walls. The effects of changing relative phase relationships, etc. has the inverse effect; the wall reflections become a crtical contributor. Given a large radiation area to the broadband content of the soundfield, the effect of this reverberation/ambience becomes more effective in creating a convincing spatial area, seemingly. Though, the effect with the mentioned 2 ch. would bel imited to producing ambient/reverberant effects that eminiate frmo the front and partially to the sides. Conveniently, this is the main requirement for sound in normal venues(minus audience and other spurious sound sources that do not originoate from the front stage, etc.). The rear side and rear contributes little to such performances. The 10.2 system, for example, should be capable of adding discrete sounds to the rear and sides, not jsut ambient effects. Also, since it has the added number of discrete sound sources, the effective 'sweet spot' should be vastly increased in size. Since the 10.2 system uses a strictly defined recording/micing process, it should prove a reliable playback system, also.

All of this is far beyond the current state of the art with 2 channels, 4 channels, 5.1 channels, or 10.2 channels.

I don't know if that's true, or not. I have never had an opportunity to hear the 10.2 system, mentioned, though I am aware of press releases about the demo. Again, if I did hear it, the best I could do is offer my subjective impressions, that is....what i 'thought' i heard. I already believe i have heard 2 channel pull off convincing performance, as I specifically stated previously. Again, I can only tell you my perception(s). I don't completely discount that I could be under heavily biased influences, severely distorting my perceptions. Based on the statements by people who have heard the 10.2 system, they seem to have believed it sounded realistic, too. But as I stated previously, lacking some way to do a proper ABX/DBT, their is no way to know if this is percieved and dependant(at least partially) on other factors, or a result of the process itself(it's refined enough to consistently create an illusion among subjects).

-Chris

[Mark of Cenla]

My what an interesting topic! I prefer good ole two-channel stereo...warts and all. Peace.