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Topic: Is there any way to measure "soundstage?" (Read 14281 times) previous topic - next topic
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Is there any way to measure "soundstage?"

On various audio forums people are always talking about the "soundstage" of headphones and speakers.  Crutchfield.com lists this in their glossary "The soundstage refers to your sense of width, depth and height when you listen to music — just as you would sense the placement of different instruments in a live concert setting. Individual vocal and instrumental "images" make up your stereo system's soundstage."

From my experiences with headphones I'd say such a thing exists.  As "proof" for the existence I present binaural recordings. So it is possible to have "soundstage" with recordings. Obviously, as displayed by binaural recordings, soundstage is a partly a factor of the recording itself.

It also seems to be something that varies from speaker to speaker or headphone to headphone and from my experience (could it be placebo?) certain headphones do have a different soundstage from other headphones. How do we know if a particular speaker or headphone actually has more soundstage than another headphone or speaker as opposed to wishful thinking or placebo from expectation?

Is there a way to measure soundstage?  It seems like it would be a good metric to have when comparing speakers.

Is there any way to measure "soundstage?"

Reply #1 –
Quote from: odigg on
Is there a way to measure soundstage?  It seems like it would be a good metric to have when comparing speakers.



Stereo (or surround, even) only gives the illusion that sounds are coming from different directions. All of the sounds are, in fact, coming from the speakers. The soundstage, therefore, is something that is perceptual; your brain makes it up (based on clues it gets from the recording and the listening environment).

Reflections from side walls do impact where we perceive the sound as coming from. You can measure how much sound is projected to the side of the speaker, but this is only half the story, you need a wall for the full effect. And everyone has a different wall/speaker set-up.

Any headphone measurements must be taken with a grain of salt because the performance of the headphone depends on the head of the person wearing it. For example,  if the driver sits exactly at the entrance of the ear canal for you, but for your friend (with giant ears) the headphones may be slightly forward of the ear canal, and there may be leaks around the sides of the headphones, which reduces bass performance..

Is there any way to measure "soundstage?"

Reply #2 –
Make a standard test recording, including some clearly identified, localized sounds in different apparent directions.

For the transducers under test, get the subject(s) to point in the perceived direction of the sound.

Measure the pointing. Statistically analyse the results.

I'm sure there are lots and lots of things wrong with that proposal, but the inclusion of a subject seems inescapable if you want to measure a mental event.

Maybe pointing out my errors, misconceptions, and breathtaking ignorance will advance the discussion?

Is there any way to measure "soundstage?"

Reply #3 –
Yeah, Michael's onto something. I was going to say before I read his post, source is everything.

Headphone'rs could be listening to Pink Floyd for all we know and talking about immersive soundstages and whatnot, when you get that effect with pretty much any setup. It depends on the source and you can't just rely on someone vaguely saying 'the soundstage is this or that', you MUST have some reference point to work from, or it's all opinion and vaguery.

I think the key will be stopping people making purely subjective 'gut' claims (as is rife in the headphone community) and basing it on some standard such as a particular test recording as Michael is getting at.

The specifics- that's for the HA nuts, not a n00b like me

- Spike

Is there any way to measure "soundstage?"

Reply #4 –
Quote from: MichaelW on
Make a standard test recording, including some clearly identified, localized sounds in different apparent directions.


Good idea - on paper. AFAIK there is not even standardized, defined sound to use.

Quote
For the transducers under test, get the subject(s) to point in the perceived direction of the sound.

Measure the pointing. Statistically analyse the results.


I'm sure there are lots and lots of things wrong with that proposal, but the inclusion of a subject seems inescapable if you want to measure a mental event.


At its core - your proposal is IMO Motherhood and Apple Pie, and I mean that in a good way.

Quote
Maybe pointing out my errors, misconceptions, and breathtaking ignorance will advance the discussion?


Here's an experiement that I did a year or two back:

At a band festival I set up my coincident mic (Rode NT4) and made a recording of a crude test sound. I found a wooden stick backstage, and then walked along a L->R straight line that was centered on where the performers would play. I tapped the stick once about every 3 feet.

The resulting recording blew me away in terms of how well it portrayed, both sonically and measurably, what I did with the stick.

On paper, X/Y or M/S recording (thay are analogous) has tons of separation and does a good job of what it claims to do.  While some may not believe it, I'm not alone in worrying about capturing too-broad of an acoustic image when using it.  It may not be optimal for creating audiophile spectaculars, but if sonic accuracy to the actual original event is on your agenda, it is at least a good place to start.

Is there any way to measure "soundstage?"

Reply #5 –
Quote from: Arnold B. Krueger on
Quote from: MichaelW on
Make a standard test recording, including some clearly identified, localized sounds in different apparent directions.


Good idea - on paper. AFAIK there is not even standardized, defined sound to use.



Well, this might be a new test, so the first recording made for this purpose would become a de facto standard.

I would guess that you would want both continuous and impulse sounds. Maybe a wind instrument--how about an oboe playing a sustained A, since there should be lots of players with practice at doing that--and a set of keys jangling, or a wood block like your experiment.

The question was about testing playback devices, so the miking isn't critical. Perhaps a method which maximizes the apparent width and separation of sounds?

The bit I'm worried about is the pointing by the subjects. You probably couldn't, with this method, compare speakers with 'phones, because with speakers there would be some influence from turning the head within the soundfield (even a little bit, involuntarily), with 'phones, not.

Is there any way to measure "soundstage?"

Reply #6 –
Just to finish my ignorant contributions, here's a research programme.

1. Make test recording(s). In a known good studio, with a mike set up generally regarded as giving good separation, record sounds at different positions. One set of three positions: centre, and two edges, separated by 60 degrees (suggested by the equilateral triangle recommendation for speaker placement). Other recordings with a number of intermediate positions, the precise number to be decided by the competent, but pretty certainly including 5 and 7 positions. The sounds to be a continuous note on a real instrument, and a sharp impulse sound (wood block or cymbal).
That bit would be easy.

2. In a known good listening room, set up the speakers under test, and record the direction in which listeners point for each sound. You probably would want to randomise the order in which different directions turn up, and you'd want a lot of runs with a number of listeners.

3. Repeat with different speakers. For a first test, choose at least one set of speakers regarded as giving a good soundstage, one set thought to be bad in this regard.

4. Analyse results. FIRST QUESTION: is there any kind of consistency to listeners' discriminations of directions, any consistent difference between different pairs of speakers? Test for width of soundstage, and variability in apparent direction of intermediately placed sounds, fineness of discrimination.

Stage 2.

Using the same speaker setups as in the first stage, and using real music as a source, run a series of suitably controlled, blinded, subjective listening tests, asking listeners to report on soundstage, and specificially on width and discrimination of instruments. SECOND QUESTION: is there any correlation between the results of the previous tests, and the reports in the subjective tests.

By the end of this process, I think you would have the beginnings of a notion of whether or not you were finding out anything, and how to proceed further.

I guess, of course, that something much better than this is widely done in the industry already, but as there was a tiny bit of encouragement, I thought I'd spell out my thoughts.

Is there any way to measure "soundstage?"

Reply #7 –
A good question to ask, are there really differences in stereo accuracy (soundstage) between different loudspeakers? If there are what would be causing those differences?

I suspect that most stereo accuracy problems are from the environment (reflections from walls) i.e. not the loudspeaker itself. Diffraction from the edge of the loudspeaker could also play a part.

I think any tests should not use a recording. A percussive test signal should be used with a number of tests using different intensity ratios in each speaker. The problem with a recording is that the recording itself may mask or alter the stereo perception of the listener.

I think we need Sean Olive to weigh in here.

Is there any way to measure "soundstage?"

Reply #8 –
MichaelW-Thanks very much for your thoughts.  I really appreciate them.  I've been thinking about this today (when I should have been paying attention to driving) and I started to think about if binaural recording would work for this.  Binaural recording does an great job at giving us aural location cues.  If we had a square room and setup a dummy head in the middle, sounds could be recorded from all around the room.  If we adjust the height of the sounds we can cover all three dimensions. 

But this raises some questions.  Is binaural recording so good at giving location cues that it doesn't really matter what headphones/speakers you use?  I've not tested every speaker/headphone in the world, but I'll assume that any speaker/headphone can be used to locate sounds when using a binaural recording.  But would there be differences between gear?  For example, let's say that I recorded sounds at 0,15,30,45,60,75, and 90 degrees.  Assume 0 degrees is in directly in front of the dummy head.  Would we find that with headphone with bad soundstage  people only seem to hear say sounds come from 0 ,45, and 90 degrees whereas with a headphone with better soundstage they could identify the directions with more accuracy?

I think this is something to figure out empirically.

There is another problem.  Soundstage is  bit of a moot point with studio recorded pop music.  But a lot of people consider it important for live and concert (e.g. classical) recordings.  I've been listening to a bunch of binaural recordings lately and I've found that locating sounds it easy when it's just a few sounds.  For any music where there is a lot of things going on (e.g. a complex classical piece), I end up feeling mentally fatigued and cannot do much more than point out left and right.  Could it be that there is just too much information coming in through my ears without other sensory stimuli to verify what my brain is calculating?  Maybe I'm just not used to binural music.

Quote from: Iain on
I suspect that most stereo accuracy problems are from the environment (reflections from walls) i.e. not the loudspeaker itself. Diffraction from the edge of the loudspeaker could also play a part.


Yes, I've been wondering about this.  A possible example of what you are talking about is the Orion++ from Linkwitzlab http://www.linkwitzlab.com/orion++.htm
The Orion++ is an open design and it even uses a rearward facing tweeter to take advantage of wall reflections.  I believe the reviewer on one online audio magazine which supports DBT (the name is not coming to me right now) said it has the best soundstage of any 2 channel speaker they've heard.  They might have even said it rivaled a multichannel setup.

This could be tested.  If it were possible to test in a anechoic chamber (or maybe just in a big field outside) speakers could be tested to see if soundstage is a quality of speakers or if reflected sound from walls plays a part.

Is there any way to measure "soundstage?"

Reply #9 –
If I recall rightly, in theory all you need to do is measure the apparant width of the image of pink noise applied identically to each speaker.  If it is precisely centered between the two speakers and if it's percieved width is zero at all frequencies then, in theory, the speaker is capable of correct imaging.  Of course, no real speaker meets that specification, all of them giving some width to the center image.  In theory the narrower the width the more accurate the stereo imaging.

If you read the abstracts published on the web about the design process for the BBC LS35a you will find that this is in fact the test they did for stereo accuracy, and indeed I believe the figures for this test are part of the specification that must be met to get a license to make them.



Ed Seedhouse
VA7SDH

Is there any way to measure "soundstage?"

Reply #10 –
Quote from: odigg on
For any music where there is a lot of things going on (e.g. a complex classical piece), I end up feeling mentally fatigued and cannot do much more than point out left and right.  Could it be that there is just too much information coming in through my ears without other sensory stimuli to verify what my brain is calculating?  Maybe I'm just not used to binural music.


Well, I don't know about binaural, but my sense is that soundstage is not really important for orchestral music. At a concert, I like to sit near the front to get an experience as different as possible from a recording, but the people I know who really know about music tend to sit halfway back, or even nearer the rear. From that position, a reasonable sized orchestra subtends quite a small angle, and the acoustics of most rooms seem to work to reduce apparent separation even more. My guess would be that in typical orchestral pieces, one is not meant to be able to hear the individual instruments/groups of instruments in a tutti. I prefer stereo, because it helps me pick out the musical lines more clearly, but I'm pretty certain you're not meant to be able to single out an individual cello.

As you say, studio pop is a whole other thing, but one topic in these discussion is realism. But perhaps the point of soundstage with orchestral music is to reproduce the effect of a particular performance in a particular space, rather than analysing out specific instruments?

Is there any way to measure "soundstage?"

Reply #11 –
Quote from: MichaelW on
Well, I don't know about binaural, but my sense is that soundstage is not really important for orchestral music.


I don't know if everybody would agree with you, but I would say you are correct.  However, I do think soundstage or a feeling of "space" makes a difference.  Some EQ settings (too much midbass being one example) can result in the sound being very congested, almost like the instruments are playing on top of each other.  A good soundstage (or EQ setting?) could give an orchestra the sound of actually playing in a hall as opposed to a entire orchestra sounding like they are crammed into a small room.  Still, in both cases, it would be about having a "wide" sound as opposed to being able to point out the exact direction of each instrument.

MichaelW - Thanks for all your replies.  Now I'll just have to apply for a government grant to fund research on this

Is there any way to measure "soundstage?"

Reply #12 –
Quote from: odigg on
Some EQ settings (too much midbass being one example) can result in the sound being very congested, almost like the instruments are playing on top of each other.  A good soundstage (or EQ setting?) could give an orchestra the sound of actually playing in a hall as opposed to a entire orchestra sounding like they are crammed into a small room.


Um, isn't this in itself a surprising finding? That EQ settings can influence apparent soundstage.  Wouldn't that be worth investigating all by itself? (Thinks: why do people faff about with sampling rates and bit-depths and stuff when the human mind has so many, and so effective, unknowns (both known unknowns and, probably, unknown unknowns, though of course we can't know that).)

Quote
MichaelW - Thanks for all your replies.  Now I'll just have to apply for a government grant to fund research on this


Maybe one of the high end audio magazines would fund some research? 

Is there any way to measure "soundstage?"

Reply #13 –
Since perception and psychology are involved, it would probably be important to have a large number of listeners involved in the experiment.  Some listeners might perceive a better soundstage from one pair of speakers, and other listeners might get a better perception from a different pair...

Since there are no measurement standards, specifications, or blind tests,  (and because I'm skeptical of almost everything!), I'd ignore anything written about a particular product relating to imaging or soundstage! Unless you really trust a particular reviewer, you'd have to listen and compare for yourself. 

I've never heard a binaural recording*, but there are special issues/problems with headphones.  In normal listening, we get quite a bit of directional information from (slight?) head movements.  Of course, head movements don't work with headphones and this is why surround-sound headphones don't work well. 

It can be very difficult to locate an impulse sound, but if the sound continues we can move our head around and get "multiple readings".  I think, most of the time these head movements are subconscious**, but when we hear an unexpected sound, we often turn our head to "see where it's coming from", and we've all seen animals turn their head when they hear a strange sound.  For example, if you think about sounds coming from directly in front, directly overhead, or directly behind, these all end-up with identical sound waves hitting both ears.  It normally takes a head movement (or movements) to get a 3D image and "zoom-in" on the location.




*  I have read about good results with binaural recordings and I do believe that "it works".  But, I assume there is much more to the perception/illusion than "soundstage" or "location".

** I don't know...  I think for most people these head movements are subconscious. But, since I know how this works and I've thought about these things, I am often very aware of my head movements when trying to locate a sound!

Is there any way to measure "soundstage?"

Reply #14 –
Quote from: MichaelW on
Um, isn't this in itself a surprising finding? That EQ settings can influence apparent soundstage...


Actually, I think it's even more interesting than that.  I have a headphone that is bass heavy and another that is bass light.  Once I've grown accustomed the bass-light headphone the bass-heavy headphone sounds congested (no soundstage) until I become acclimated to the bass-heavy headphone.  So the impression of soundstage is not only a property of the headphone, but also a property of psychology as you stated.  It's also not surprising that people typically report that very expensive headphones ($1000) always have magically large soundstages.  If a person can hear massive changes in FR with a cable, why not soundstage based on price?

There are definately a lot of psychological unkowns with how humans hear music.  I suspect that our subjective interpretations of transient response is also dependent on the FR of the transducers.

Quote
Since perception and psychology are involved, it would probably be important to have a large number of listeners involved in the experiment.


100% agree with you.

Quote
I'd ignore anything written about a particular product relating to imaging or soundstage!


I think there are two general rules of thumb I support but I would need to verify somehow.  Headphones with angled drivers seem to have more soundstage than headphones without angled drives. Headphones with an open design also seem to have greater soundstage than headphones with closed designs.

Quote
I think, most of the time these head movements are subconscious


If nothing else our attention changes focus (almost before we are consciously aware of it) when something peculiar sounds.  At least with me, I sometimes turn my heads or eyes a bit along with this focus to the left or right even when I'm using headphones and hear something curious.  My focus shifts quickly, perhaps before I even realize it.

Is there any way to measure "soundstage?"

Reply #15 –
Quote from: odigg on
I have a headphone that is bass heavy and another that is bass light.  Once I've grown accustomed the bass-light headphone the bass-heavy headphone sounds congested (no soundstage) until I become acclimated to the bass-heavy headphone.


I've just had one of those blinding glimpses of the obvious. High frequencies are more directional than low ones (effect of wavelength and size of sensors--ears--I guess). So, psychologically, perhaps our sense of direction is linked with our perception of direction. So, I speculate, maybe our sense of directionality is swamped if we perceive the sound as bass-heavy.

The empirical testing of this wild guess is left as an exercise by the competent.

Is there any way to measure "soundstage?"

Reply #16 –
Quote from: MichaelW on
Quote from: odigg on
I have a headphone that is bass heavy and another that is bass light.  Once I've grown accustomed the bass-light headphone the bass-heavy headphone sounds congested (no soundstage) until I become acclimated to the bass-heavy headphone.


I've just had one of those blinding glimpses of the obvious. High frequencies are more directional than low ones (effect of wavelength and size of sensors--ears--I guess). So, psychologically, perhaps our sense of direction is linked with our perception of direction. So, I speculate, maybe our sense of directionality is swamped if we perceive the sound as bass-heavy.

The empirical testing of this wild guess is left as an exercise by the competent.


I think what really happens is that many people get really distracted when things don't sound right tpo them.

They then can't do good analytical listening with unfamilair wound like they can do with more familiar sound.

One stage of ear training is where you listen to something and you listen through the obvious faults and also hear the more subtle ones. Or, you listen to something in one context and can accurately imagine what it would sound like in another.

Is there any way to measure "soundstage?"

Reply #17 –

[/quote]


One stage of ear training is where you listen to something and you listen through the obvious faults and also hear the more subtle ones. Or, you listen to something in one context and can accurately imagine what it would sound like in another.
[/quote]

As opposed to audiophile training: Learning to inaccurately imagine what it would sound like if you had actually received your money's worth.

Tim

Is there any way to measure "soundstage?"

Reply #18 –
Quote from: tfarney on
Quote

One stage of ear training is where you listen to something and you listen through the obvious faults and also hear the more subtle ones. Or, you listen to something in one context and can accurately imagine what it would sound like in another.


As opposed to audiophile training: Learning to inaccurately imagine what it would sound like if you had actually received your money's worth.



Yes you're kidding.

I think that you have touched on an operative process in many high end audiophile's enjoyment of their hobby.

A lot of people are interested in bragging rights down at the water cooler, gym or coffee shop.

I happen to live in a community were bragging rights are first based on where you live and how big your boat is. Living in a big new house down on the water with a big powerful boat in the water down at the msot exclusive club is what the people who rule the bragging rights derby do.

Is there any way to measure "soundstage?"

Reply #19 –
Quote from: MichaelW on
So, I speculate, maybe our sense of directionality is swamped if we perceive the sound as bass-heavy.


If I combine this with

Quote
I think what really happens is that many people get really distracted when things don't sound right tpo them.


I end up answering a question I have about where the test should be held.  Would it be better to do a large soundstage test at a public gathering (like an Audio convention) or let people do it at home.

If an unfamiliar sound signature is going to muddy up an analysis of soundtstage than it makes little sense to have people do this in a public gathering where they are testing different speakers/headphones one after another.  It would make far more sense to create something like a web based test they can take at home.  Granted, perhaps the results lose some validity because the test conditions cannot be controlled as rigorously as in a public gathering, but the trade off seems to make sense.