Soundstage, stereo vs mono vs surround

[STC]

Because mono doesn't exist in the natural world (sound from the same or different sources being all around us) our brains they try to make spatial sense of it.

Actually there is no stereo in nature. Essentially, all sound originates from a single point. Having said that the size of the point varies accorsing to the source.

Stereo is the next best choice to recreate the soundstage by employing level difference. In nature, the soundstage is create by timing, level and HRTF.

 

[GrimSurfer]

Actually there is no stereo in nature. Essentially, all sound originates from a single point. Having said that the size of the point varies accorsing to the source.

Stereo is the next best choice to recreate the soundstage by employing level difference. In nature, the soundstage is create by timing, level and HRTF.

That's not entirely accurate, especially when dealing with musical instruments.

Pluck a guitar string. The string resonates at a frequency along its length -- around two feet. The body resonates, front, back, sides, with a primary source from the sound hole.

The sound reaches your ears in direct path, as well as first, second reflection points tangential to the source.

The sound of rustling leaves is coming from thousands of individual points... In nature, you're never presented with one sound, but many from different points.

I could go on, but the mono myth doesn't hold water. It's a very simple (I'm loathe to use "simplistic", which could be interpreted as condescending... but (no insult intended) that's a better adjective) way of conceptualizing sound.

 

[STC]

That's not entirely accurate, especially when dealing with musical instruments.

Pluck a guitar string. The string resonates at a frequency along its length -- around two feet. The body resonates, front, back, sides, with a primary source from the sound hole.

The sound reaches your ears in direct path, as well as first, second reflection points tangential to the source.

The sound of rustling leaves is coming from thousands of individual points... In nature, you're never presented with one sound, but many from different points.

I could go on, but the mono myth doesn't hold water. It's a very simple (I'm loathe to use "simplistic", which could be interpreted as condescending... but (no insult intended) that's a better adjective) way of conceptualizing sound.

The indirect sound that reaches your ears is consistent irrespective whether the sound is from a single source or two like a stereo speakers arrangement.

If you were to listen to a band playing in a reflection free room, you would still preceive the soundstage because TLD, ILD is still presence without the indirect sound. Although, the sound in a reflection free room will sound dead to our ears because in nature the reverberation shapes the the sound and we are used to it.

 

[GrimSurfer]

The indirect sound that reaches your ears is consistent irrespective whether the sound is from a single source or two like a stereo speakers arrangement.

If you were to listen to a band playing in a reflection free room, you would still preceive the soundstage because TLD, ILD is still presence without the indirect sound. Although, the sound in a reflection free room will sound dead to our ears because in nature the reverberation shapes the the sound and we are used to it.

First of all, that band has a soundstage because it consists of a variety of sound sources (instruments) arranged spatially across a stage. That makes it something other than mono.

It isn't inconsequential, because (for evolutionary reasons) the human auditory system places a very high priority on locating sound in three dimensions. It is one of the things that helped early man from being gobbled up by larger critters lurking in the forest.

Your comment on TLD and ILD demonstrate this nicely.

So even when listening to a single artificial mono source in an anechoic chamber (which is definitely not representative of what happens in nature),we'd still try make sense of things according to our evolutionary development.

 

[STC]

Sorry typo- it is ITD. Not TLD, my mistake.

 

[GrimSurfer]

No biggie.

 

[STC]

First of all, that band has a soundstage because it consists of a variety of sound sources (instruments) arranged spatially across a stage. That makes it something other than mono.

Not sure I understand you. How human localize sound has been anaylzed in detail by Blauart in Spatial Hearing.

In stereo, we call the images in between the two speakers as phantom images because they do not exist but the mind is being tricked with leval difference to create an illusion as if , say a trumpet, is located as 30 degrees to the left.

In nature, a trumpet located at 30 degrees will be localize with HRTF. A trumpet is still a mono sound but the position is located based on the HRTF. The same applies to the rest of the instruments forming the soundstage.

I am not sure how this is stereo. Himan do not hear in stereo. We hear binuarally. Although, Blumlein wrongly called his invention as binuaral before changing it to stereo, it is still an artificial reproducing of the soundstage based on level difference alone, although the ITD contained in most recordings they are not retrieved in the stereo playback.

 

[GrimSurfer]

Not sure I understand you. How human localize sound has been anaylzed in detail by Blauart in Spatial Hearing.

In stereo, we call the images in between the two speakers as phantom images because they do not exist but the mind is being tricked with leval difference to create an illusion as if , say a trumpet, is located as 30 degrees to the left.

In nature, a trumpet located at 30 degrees will be localize with HRTF. A trumpet is still a mono sound but the position is located based on the HRTF. The same applies to the rest of the instruments forming the soundstage.

I am not sure how this is stereo. Himan do not hear in stereo. We hear binuarally. Although, Blumlein wrongly called his invention as binuaral before changing it to stereo, it is still an artificial reproducing of the soundstage based on level difference alone, although the ITD contained in most recordings they are not retrieved in the stereo playback.

Ok, let me clarify. You started talking about how everything in nature was monaural. I categorized this as a simplistic view, using an example of how a plucked guitar string was anything but monaural given that it's sound does not emirate from a single point but from many points.

You then suggested that a band in an anechoic space would be mono. I contend that they are not. This issue isnt a case of the lack of reflections, it's the fact that a band is a collection of players occupying different space on a stage. Because they occupy different space, the sound that their instruments make will reach the left and right ears at different times. Our hearing system, which evolved as a detection and spatial orientation capability, will perceive this sound as occupying at least two, and possibly three, dimensions. So a band playing on a real stage is not producing sound in mono. Their instruments are not and their orientation across the stage simply doesn't support this.

Adding on to this, an anechoic chamber isn't found in nature. It's a man made device. It has some of the basic characteristics of a free space (no perceived echos),but it lacks certain others such as spurious noises from multiple directions. (What's the quietest place you've been to? For me, it's a toss up between the open desert and arctic... but even at night, far from camp, there is noise all around, which means that your auditory system is still working in 3D.)

Spatlial displacement in a stereo system is an illusion. So is spatial displacement in an 11.2 system, which is a better illusion but still and illusion. The illusion of displacement in two or three dimensions is facilitated by our auditory system. That system, developed over millions of years, was designed for simple detection and spatial orientation. We can no more turn that off than we can expect our eyes to perceive colors in monochrome.

 

[<eargiant]

I don't think the speakers themselves, so long as they are optimally placed and set up, have that much impact on the imaging.

I disagree 1000%. You would think differently if you came over to my room and A/B'd my level matched Bowers & Wilkins CM6 vs the my 805D2 (just to name two speakers). As good as the "LEV" & "ASW" is with the CM6 (they blew away KEF LS50 in that respect in a non-nearfield set-up) the definite improvement in "LEV" & "ASW" with the 805D2 is undeniable. Just jaw dropping...

I have alway wanted to know what specific spec or measurement one can look at to determine the "LEV" & "ASW" of a set of speakers and I have never found a good answer. I don't think one exists, you have to listen and compare.

 

[STC]

Ok, let me clarify. You started talking about how everything in nature was monaural. I categorized this as a simplistic view, using an example of how a plucked guitar string was anything but monaural given that it's sound does not emirate from a single point but from many points.

You then suggested that a band in an anechoic space would be mono. I contend that they are not. This issue in this case isn't the lack of reflection, it's the fact that a band is a collection of players occupying different space on a stage. Because they occupy different space, the sound that their instruments make will reach the left and right ears at different times. Our hearing system, which evolved as a detection and spatial orientation capability, will perceive this sound as occupying at least two, and possibly three, dimensions. So a real band playing on a real stage is not producing sound in mono. Their instruments are not and their orientation across the stage simply doesn't support this.

Adding on to this, an anechoic chamber isn't found in nature. It's a man made device. It has some of the basic characteristics of a free space (no perceived echos),but it lacks certain others such as spurious noises from multiple directions.

Spatlial displacement in a stereo system is an illusion. So is spatial displacement in an 11.2 system, which is a better illusion but still and illusion. The illusion of displacement in two or three dimensions is facilitated by our auditory system. That system, developed over millions of years, was designed for simple detection and spatial orientation. We can no more turn that off than we can expect our eyes to perceive colors in monochrome.

The resonance of the instruments does not extend to the opposite side. I mentioned earlier that the point can be small or big. It is still a mono sound. Perhaps, mono is not accurate but it reflects the actual position of the real instruments which is coming from a single direction.

http://www.anstendig.org/Stereo.html

 

[BMXTRIX]

I think this was a good simple read...
https://knowingneurons.com/2013/03/15/how-does-the-brain-locate-sound-sources/

The concept that we can locate sound in all three dimensions is really the crux of humanity. For those who hear well up to this point, it is not a thing we turn off. We hear all the time, and we practice location with our ears all the time. Stop, for a second, listen to the world around you right now. Use your brain to isolate sounds around you and not only their direction, but their height.

I think it has been covered well that concerts are on a stage, and without speakers for reinforcement, the stage itself and the room itself creates an impact that is far more than mono or stereo. If a recording were to be made in stereo, then the surround modes of an A/V receiver are designed to recreate the sound of a particular venue. The reflections, the delays, etc

But, the concept of surround sound, and perhaps far better with Atmos is the ability to place a specific sound into a space where it should be heard. Ceiling speakers may be enhanced at some point with speakers on the ground... and it goes on and on. But, Atmos, for a single listener, may be the best way to truly give an exact representation of what a environment will sound like with some degree of accuracy.

So, sound from an instrument is very close to mono, but the actions of the environment completely change that sound not to just stereo, but far more.

And we practice by listening every moment of every day with such high complexity through natural means, that it is unlikely to ever be reproduced with any real accuracy. Despite all that we have done, we have a long (long!) way to go. Kind of like holography vs. 3D.

 

[GrimSurfer]

I disagree 1000%. You would think differently if you came over to my room and A/B'd my level matched Bowers & Wilkins CM6 vs the my 805D2 (just to name two speakers). As good as the "LEV" & "ASW" is with the CM6 (they blew away KEF LS50 in that respect in a non-nearfield set-up) the definite improvement in "LEV" & "ASW" with the 805D2 is undeniable. Just jaw dropping...

I have alway wanted to know what specific spec or measurement one can look at to determine the "LEV" & "ASW" of a set of speakers and I have never found a good answer. I don't think one exists, you have to listen and compare.

I've got to agree with @<eargiant on this one. Ribbon tweeters and electrostatic speakers have unique dispersion patterns that placement and orientation cannot change to a point where their spatial output is indistinguishable from conventional designs. Their dispersion characteristics are due to their design.

 

[GrimSurfer]

The resonance of the instruments does not extend to the opposite side. I mentioned earlier that the point can be small or big. It is still a mono sound. Perhaps, mono is not accurate but it reflects the actual position of the real instruments which is coming from a single direction.

http://www.anstendig.org/Stereo.html

You're getting closer... just a few more steps to go.

An instrument's resonance does extend to the other side. Think drums, acoustic guitars as easy-to-imagine examples. Drums have elastic surfaces and resonant sides that transmit sound in 360. The back of an acoustic guitar does the same because it too is elastic (wood is both reflective and reflexive to sound).

You may not think that you hear this, but you do. It's what gives sound it's tonality and resonance... and it's not coming at you from one direction but from many (fundamental frequency, resonant frequency, sidelobes, reflections etc.).

I think you're onto something with the position of instruments. It's just that the sound from an instrument or a group of instruments doesn't hit our ears like a laser beam (coherent, focused and unidirectional). It washes over us like waves and wavelets in a bay... from a variety directionS, some direct, some delayed (back reflections of a guitar emanating from the sound hole),some dispersed, some reflected.

 

[William Lemmerhirt]

Something else to think about is that most recordings are made by tracking the instruments and vocals separately. All the magic is done at the board, and in post.

 

[GrimSurfer]

Something else to think about is that most recordings are made by tracking the instruments and vocals separately. All the magic is done at the board, and in post.

Absolutely right... like so many of your posts @William Lemmerhirt. Changing phase and intensity of individual tracks, etc. can really change the overall sound... and our perception of it. This is all because our auditory system is actively trying to place and locate individual sounds on a track, even if it is coming out of one speaker.

 

[GrimSurfer]

While on the subject of mono, stereo etc., I would like to point out that increasing the number of channels increases the chances of getting closer to natural sound as long as the following conditions are met in scale of importance (most important first):

1. Selecting the best source material/format;

2. Selecting playback devices and loudspeakers that maintain exceptionally good control of tone, timbre, and intensity across the audible range, as well as being properly matched so that they operate efficiently and effectively as a whole;

3. Placing speakers in the best possible location within a space;

4. Employing some kind of sound treatment to mitigate the most unwanted/unhelpful room effects;

5. Correcting for the interaction of the loudspeakers and the space using an instrumented device (i.e. room correction software, test tones and spl meter or both).

These are all qualitative in nature. They require consideration and attention to detail and are independent of watts, number of channels, or any particular price point.

 

[lovinthehd]

Hard to think of all the various sound sources around one in real life not being surround in action vs thinking of things as one source point particularrly unless maybe a solo instrument performance outside...I like Grim's idea of an infinite number of transducers all around one as the ideal playback system....maybe technology can yet improve upon current immersive type multich surround systems for normal rooms.

 

[GrimSurfer]

Hard to think of all the various sound sources around one in real life not being surround in action vs thinking of things as one source point particularrly unless maybe a solo instrument performance outside...I like Grim's idea of an infinite number of transducers all around one as the ideal playback system....maybe technology can yet improve upon current immersive type multich surround systems for normal rooms.

Thanks, @lovinthehd. I believe we will get there at some point. Perhaps through a variation on a flat panel speaker, but on a larger scale that operates as a wall panel. Certainly using some heavy duty processing to dynamically adjust levels to match the room and where people are (and moving to) in it. (Which is why I admire the AVR enthusiasts' acceptance of this kind of tech, which hasn't yet caught on for mainstream two channel listeners)

The key to all of this will be perfecting the fundamentals of frequency, frequency response, and distortion-free sound (which is why I admire two channel enthusiasts obsession with sound quality), as this will reduce the immense processing power that would otherwise be required.

We're far from this at the moment because of divisions between the two-channel and multi-channel market, which the corporations themselves created. These divisions make it easy to sell gear ranging from dirt cheap (90% of the market with tight margins) to excessively expensive (10% of the market with huge margins)... but they don't do anything to change the fact that we're still some distance away from being able to reproduce sound in our spaces that is indistinguishable from the real thing.

 

[STC]

An instrument's resonance does extend to the other side. Think drums, acoustic guitars as easy-to-imagine examples. Drums have elastic surfaces and resonant sides that transmit sound in 360. The back of an acoustic guitar does the same because it too is elastic (wood is both reflective and reflexive to sound).

I was referring to the resonance extending to the right or left side as left and right speakers of stereo. Unless you are referring to large piano placed infront of you forming a 60 degrees stage.

All sound disperse 360 degrees. What matters to our hearing is the direct sound that arrives to our ears first.

As long as the second sound that arrive to the opposite ear is within about 1ms that information is decoded for localization. Using your example, the radiating sound to the back or side will arrive later than 1ms. This adds to spaciousness.

There were demos in concert hall using multiple mono speakers which successfully fooled most listeners as the original sound. These experiments were conducted in the late 50s and 70s.

In recordings, the mic is usually placed much closer than the critical radius so that to prevent the capturing of the indirect sound. Ideally, these indirect sound are essential for recreating the true ambiance during playback but as in nature it must come from a different direction than the direct sound. With a single or two speakers, this is not possible otherwise the recording will sound muddy. This is where multichannel recording comes in where the ambiance is reproduced via the surround channel.

I am confining this discussion to music with the stage assumed to be infront. Most of this discussion will not apply for object based sound multichannel teproduction where it is meant for HT and games where the sound ir ibject is intended to be surrounding you.

 

[GrimSurfer]

I was referring to the resonance extending to the right or left side as left and right
speakers of stereo.

Sound radiates 360 degrees from these devices too. The drivers have something called dispersion, which varies according to the basic design of the driver (horn, cone, panel etc.). There's a fairly substantial back-wave (cone, panel). There's a phase shifted wave from a backward firing port that is of the same fundamental frequency of the driver, but with greater intensity at the resonant frequency of the port. There's a time late wave from a front firing port (same characteristics as the backward fixing port). The cabinets resonate in all directions.

All sound disperse 360 degrees.

Correct.

What matters to our hearing is the direct sound that arrives to our ears first.

That's a broad statement. Matters for what? Lots of things matter in hearing, frequency, phase, intensity, Doppler...

As long as the second sound that arrive to the opposite ear is within about 1ms that information is decoded for localization. Using your example, the radiating sound to the back or side will arrive later than 1ms.

This totally depends on the difference in distance that sound travels via direct path and reflection. Influences on this include angle from the reflecting surface, distance from the reflecting surface, distance between the driver and the listener, orientation of the ears relative to source and reflections....

This adds to spaciousness.

It can also create smearing, combing, and huffing, and a whole bunch of other audible effects.

There were demos in concert hall using multiple mono speakers which successfully fooled most listeners as the original sound. These experiments were conducted in the late 50s and 70s.

I'd be interested in reading that paper. Please keep in mind that a music hall is a space designed for the propagation of sound and to manage its reflections. The sense of spaciousness is a function of carefully oriented reflecting points. It is also designed to preserve the sound stage for listeners because it would be distracting to have the band in one location and the sound coming from another. This is a balancing act... too many reflections will disturb the sound stage. Too few, and the sound will be lifeless.

But all of this is a gross simplification of sound, because human hearing relies on other things too in order determine direction and distance.

I am confining this discussion to music with the stage assumed to be infront. Most of this discussion will not apply for object based sound multichannel teproduction where it is meant for HT and games where the sound ir ibject is intended to be surrounding you.

You started out talking about natural sounds. Then you moved to reproduced sound. Now the discussion is restricted to music... but not multichannel music, which is a feature of BluRay and DVD-A.

The truth of the matter is that sound does surround us. This is why it has been devilishly difficult for loudspeaker manufacturers (who actually have increased the performance of their products since the 1950s, 60s, and 70s) to deliver life-like sound.

I have no doubt that drivers (and perhaps even drivers supplied by a single channel of music) can trick the auditory system to a degree. But this requires a carefully controlled space that imparts effects that approximate those produced by real instruments in natural (not free space and not in an open field, but in places where we become familiar hearing them) locations. These effects include resonance, direction, reflection, phase, etc. But move a driver, hang a curtain, or change perspectives, and this illusion can be shattered.

Why? Because human hearing uses a lot of cues to determine what is real, what is close, what is far, what is approaching, what is moving, etc.

So, to go back to your original point, natural sound isn't monaural. Reproduced sound may emanate from a single driver, but it ceases to become a single point in time and space the moment it starts interacting with the physical world. If this is what you equate as monaural, then so be it. But then it diverges from your original premise.