Importance of impulse response

[fineMen]

1st sample in test signal "1Wa" is around 300 ms, without time-reversing:

2nd sample in test signal "1Wa" is around 1300 ms, with time-reversing:


Time scale of the second sample is reversed to make difference to phase response and group delay. Amplitude responses are exactly equal. Got it?

Thanks a lot for coming back to this, appreciated. But again my question isn't answered. I quote myself:

The 'white paper' tells that the few people in the test panel had to decide, if there was a difference between two signals:
x) an original monophonic testsignal with especially a bit more low frequency content, played over headphones simultaneously into both ears
y) the same testsignal, but ... (please explain in detail)

What does the 'time-reversal' do?

Now you only described, what it is, or in particular how it looks like to the eye. What does it do in case (y)? I need the logic behind it (regularly I'm quite competent to analyse the logic of things).

 

[fineMen]

What did Griesinger use in this video to demonstrate and why?

Coming back to this again. Much talking, very much fear mongering and even less proof. Only speculation.

You don't have to, you're not adding anything useful. You're just in denial.

I see, my clear argumentation before spoils that talking around.

If you want the first, read Mr. Griesinger's papers. That video is just a start. By the way, the Pro industry, including the recording business is quite aware of the perception of phase. It's where I got my information from to be able to do the same.

Have a look there ( http://www.davidgriesinger.com/asa05.pdf ), especially go through the list of references. Griesinger refers to himself only which I think is suspicious. There is absolutely no experimental proof, neither done nor suggested, just none.

AES is not science, it is marketing. Guess from what I know.

 

[NTK]

AES is not science, it is marketing. Guess from what I know.

You can count the Acoustical Society of America in it too, then, since they awarded Dr Griesinger with a medal.

 

[fineMen]

You can count the Acoustical Society of America in it too, then, since they awarded Dr Griesinger with a medal.

Was it really the gold medal? Anyway, Dr. Griesinger's talking point is phase coherency mostly with people's talking (pun not intended). But, dear hifi-buffs, if you might have dared to read an article, mostly devoid of mathematics and strictly performed experimentation, then you might have read the magic number: 100. Namely 100ms. We are talking 1ms here, aren't we? One per cent of that talking point of Dr. Griesinger. And also Dr. Griesinger says, there is an effect, but I (Dr. Griesinger) do not understand it.

Why don't you understand the articles, white and scientific papers that you throw into the discussion?!

 

[Wesayso]

Luckily I'm not trying to turn you, @fineMen. I brought up the work of David Griesinger for the readers of this thread that are truly interested in the "why phase matters" discussion. I've done the song and dance with you before, not going there again.

I'm pretty sure that Toole, Olive, Geddes etc. all would agree that Mr. Griesinger is the expert in 'understanding electroacoustics and human perception of sound' as well.
That's a good enough reference list for me. All readers here interested in the 'human perception of sound' should be (made) aware of his name i.m.h.o.
Famous for his work for Lexicon making reverb algorithms for hard and software and, among other things, Logic 7.

Some fun articles spanning his career:
https://www.vintagedigital.com.au/lexicon-224-digital-reverberator/
https://www.soundonsound.com/people...con-creating-reverb-algorithms-surround-sound
https://www.audioholics.com/audio-technologies/surround-sound-upmixer

 

[NTK]

Now you only described, what it is, or in particular how it looks like to the eye. What does it do in case (y)? I need the logic behind it (regularly I'm quite competent to analyse the logic of things).

It seems the logic is pretty clear to everyone else in this discussion.

 

[Wesayso]

Was it really the gold medal? Anyway, Dr. Griesinger's talking point is phase coherency mostly with people's talking (pun not intended). But, dear hifi-buffs, if you might have dared to read an article, mostly devoid of mathematics and strictly performed experimentation, then you might have read the magic number: 100. Namely 100ms. We are talking 1ms here, aren't we? One per cent of that talking point of Dr. Griesinger. And also Dr. Griesinger says, there is an effect, but I (Dr. Griesinger) do not understand it.

Why don't you understand the articles, white and scientific papers that you throw into the discussion?!

I guess that you didn't quite get what Griesinger said. Simply scanning some of his articles won't help you understand. care to quote him instead of just naming a number?
Taken out of context, a number like that means nothing.
That's what I'm betting on, you taking another thing out of context here (again), like you've done before in this thread (and others). Heck, why do I even bother to reply. I don't care if you sway your opinion (that's set in stone already). You won't sway my opinion as it is based on personal experience.

One note: Toole is a proponent of using early reflections to create a sense of space and envelopment. Griesinger's theory does not support that point of view. Mentioning that all early reflections degrade the imaging. You can still get spaciousness and envelopment though, just follow Griesinger's lead.
I definitely have to side with Griesinger, and in the absence of those early reflections, I found that phase does matter for perception. I decided to test this for my own education and/or pleasure, instead of relying on 'hear say' on a forum.

Personally I think that checking phase audibility trough headphones is telling only half the story. We feel music as well as hear it.
If you never felt some notes on your eye lids as well as heard them being played simultaneously, you're missing out on the senses that contribute to musical enjoyment.
And that is just one example. We listen with our whole body, not just the ears.
Music played with a wide frequency bandwidth and following minimum phase throughout that bandwidth at the listening spot will be able to startle you much like "live music".
Avoidance of early reflections (at least the first ~20 ms) will also maximize imaging capabilities, the harmonics that are preserved in the recording will make it easier to follow the music as well as separate them from other sounds in the composition. Granted, not all harmonics will be preserved in all recordings, but why throw away what is still there.
The ability to do so its out there and it works, just try it for yourself. Preferably without the haze of early reflections to listen trough getting in the way.

 

[Wesayso]

Why don't you understand the articles, white and scientific papers that you throw into the discussion?!

I'm not the one confusing pitch detection with group delay...

 

[fineMen]

It seems the logic is pretty clear to everyone else in this discussion.

View attachment 248416

And still there is no relation to performing the discriminating test with focus on regular phase distortion aka group delay with a headphone playback (mono, both ears) as a model for loudspeaker playback in-room. What other get, I don't know.

In particular, why would one want to have maximum phase difference, what is the purpose of that?
I argue something, but obviously that's not what other get "clearly". It was in the very first paragraphs of the 'white paper'. If I''m right, the investigation speaks exactly against the perceptibility of 'phase distortion'.

What appears clear to me is that some may thoughtlessly trust the statement to be relevant, and give nothing else to it. Which is a pity anyway.

 

[fineMen]

One note: Toole is a proponent of using early reflections to create a sense of space and envelopment. Griesinger's theory does not support that point of view. Mentioning that all early reflections degrade the imaging.

Yes and no. I don't think Griesinger has such a clear focus on stereo as to state that early reflections degrade 'imaging' (which is a marketing term only, btw)).

You can still get spaciousness and envelopment though, just follow Griesinger's lead.

Agreed, but Griesinger doesn't address the widely inevitable 'phase distortions' as they appear in speaker-tech. What I read was all about early reflections, which, to begin with, come from other directions than 'phase'. To take his honourable work as proof for silly 'audiophile' nonsense is the evil deed I'm talking about.

I myself experimented with highly directional speakers and added quite late, diffuse adjustable reflections from the room. This was documented here, no interest--at all!

I definitely have to side with Griesinger, and in the absence of those early reflections, I found that phase does matter for perception. I decided to test this for my own education and/or pleasure, instead of relying on 'hear say' on a forum.

Good move! And likewise that's the essence of my caveats. Forums mislead people due to lack of ... personal responsibility maybe?

Personally I think that checking phase audibility trough headphones is telling only half the story. We feel music as well as hear it.
If you never felt some notes on your eye lids as well as heard them being played simultaneously, you're missing out on the senses that contribute to musical enjoyment.
And that is just one example. We listen with our whole body, not just the ears.

And again I feel deficiant, in that my ability to enjoy the most precious stereo equipment is retarded. At least that fits my mental abilities, sure. So I'm left with sitting on my friend's grand piano getting Schubert's songs explained. Pity me, with stereo I neither feel immersion nor involvement

 

[Wesayso]

Yes and no. I don't think Griesinger has such a clear focus on stereo as to state that early reflections degrade 'imaging' (which is a marketing term only, btw)).

You make of 'imaging' what you like, I do not share that opinion. Griesinger didn't speak about Stereo at all in this particular video. It's all about perception of humans, and mostly related to halls etc. He has way more work than this though, but that wasn't the point of showing this particular video. What is the point is that he stated: human phase detection works over a larger part of the frequency spectrum than was previously assumed.

Agreed, but Griesinger doesn't address the widely inevitable 'phase distortions' as they appear in speaker-tech. What I read was all about early reflections, which, to begin with, come from other directions than 'phase'. To take his honourable work as proof for silly 'audiophile' nonsense is the evil deed I'm talking about.

Think a bit harder, you're not quite getting it why I showed the video. Now his work has been upgraded to 'honourable' work, at least that's something worthwhile. I didn't get that same impression from you in your earlier replies. Well deserved though in the case of Dr. Griesinger.
Read all (global) reports of people that have studied the audibility of phase rotations induced by crossovers. The most often stated reaction: sure I've heard some tonal differences, but that was only minor. I don't even know which I preferred.
Now go back to the Griesinger studies/video and see what he has to say about our ability to detect pitch and the role of phase:

Onsets of speech and musical sounds are far more important to comprehension than the way sound decays. The small segment of direct sound that carries with it accurate information about the timbre and localization of the source is often quickly overwhelmed by reflections. To predict acoustic quality we need to know under what conditions precise data on timbre and localization are lost.

Our ability to separate the harmonics in the vocal formant range from two or more sources at the same time depends on the phase alignment of the harmonics from each source. The phase alignment of the harmonics from each source creates amplitude modulation of the basilar membrane at the frequency of each fundamental, and these modulations combine linearly. The brain stem can separate them from each other and from background noise by their pitch.

Would you think it is easier to recognize pitch when played back with a pure minimum phase system or one that has phase rotations due to crossovers, most probably at crucial points in frequency? Think back about those differences people observe in the tests done on the perception of crossover phase rotation. I know which one I would gamble on being "more correct". As long as the means to come to that result don't disturb or destroy the main pulse. So be aware of things like pré ringing. It's better (if you can) to avoid it.

And Griesinger said about reflections:

Reflections from any direction alter the phase relationships between harmonics of complex tones, reducing and randomizing the amplitude modulation of the basilar membrane. The result is intermodulation between sources, distortion, and noise. Separation of sources by pitch becomes difficult. The brain stem must revert to a simpler method of decoding sound. The sources blend together, and only the strongest of them can be accurately perceived and localized.

I know and realize he's not talking about Stereo reproduction, but the workings of human hearing is important if we want to maximize listening pleasure. If we allow early reflections we sure know we won't keep those harmonics in check that allows us to hear separate voices, instruments etc. I say it is as bad an idea as it is in the halls made for listening to concerts. Same goes for the phase rotation, if we don't have to have this rotation, we keep the signal more true to the source. As long as the way we can unfold the phase, or even avoid the rotation does not degrade the onset of those sounds that form the "close proximity". You'll have to excuse my English, I'm not a native English speaker. What I do is maximize my 'shot' at the direct sound, very low levels of reflection, very low diffraction, and following minimum phase.

I myself experimented with highly directional speakers and added quite late, diffuse adjustable reflections from the room. This was documented here, no interest--at all!

I haven't done or said anything to generate interest, weather I got it or not. I do what I do to learn, I share it because the following discussions trigger new experiments to learn more. But I understand the lack of interest. It happens to me too. Valuable research like that of Dr. Griesinger should also attract more attention i.m.h.o.
I do add ambience, virtually created. Using additional tools created by Dr. Griesinger (Lexicon Random Hall plugin).

Good move! And likewise that's the essence of my caveats. Forums mislead people due to lack of ... personal responsibility maybe?

If phase rotation audibility is valid or not is only part of the whole story of Stereo perception. We have to deal with inter-aural crosstalk when listening to speakers in a Stereo triangle which also doesn't make things easier. But instead of simply denying the ability? I'd rather welcome people to make up their own mind, should they be interested. On this forum I notice an almost blind following of the teachings of Toole. Yet, after studying the various parts of our hearing system and the way stereo works, I've come across a lot of contradictions. Dr. Geddes always said: (early) reflections degrade our capability of imaging. You can call it a marketing term, I've come to appreciate it, as the more I have learned and applied to my room + speakers (as a system that works together), the more enjoyable it became. Before that happened, I could care less about imaging and everything that was important to me was tonal balance and dynamics. These two still land higher on the list than imaging, but boy is it fun if you (can) get it all at once!

And again I feel deficiant, in that my ability to enjoy the most precious stereo equipment is retarded. At least that fits my mental abilities, sure. So I'm left with sitting on my friend's grand piano getting Schubert's songs explained. Pity me, with stereo I neither feel immersion nor involvement

I can't and won't speak for you. For me, music ranks up there as one of the most important parts of my life. Be it the live music I've been fortunate enough to witness or the joy of hearing good music (and being able to enjoy it) on a Stereo. That enjoyment of Stereo went way up, the more I learned about it and the more I could detect and influence this crazy, slightly broken "invention". The soundtrack of my life has been 'locked up' into this Stereo format, the music that I love, hold dear and have an emotional connection with. So I've decided to find "my way" in this puzzle of sound, to maximize my listening pleasure. To do so I've build my own speakers, changed up the room within the rules set by my spouse and started working/thinking and applying all I could come up with to really max out (my) listening pleasure. Dare I say I've accomplished more than I ever could imagine in advance.

One thing I promised myself: Don't get caught up in the game of building several speakers, instead choose one you believe in and optimize that. Keep playing the songs you love. Those are the songs that count! I need to be able to enjoy the "soundtrack of my life". That's the whole point, for me anyway.

The system doubles as a HT capable system and I'm actually starting to appreciate that too!

 

[fineMen]

I can't and won't speak for you. For me, music ranks up there as one of the most important parts of my life.

For the time being I assume you kind of understand my perspective, while not agreeing. Fair enough. I'll come back to this later.

 

[Wesayso]

Way earlier than this thread, this subject has been discussed with some different participants. The most notable input in that thread for me was this post by @mitchco.

https://www.audiosciencereview.com/...t-matter-in-audio-no.24026/page-2#post-809585

Mitch was of influence for my own journey into DSP quite a while ago and we've had many conversations trough the years. I can state that my experience has been similar for bass management. I've optimized my Bass to still function in stereo, parts of it using techniques that resemble the multisub solution.

To all: feel no need to believe me or anything I say. Just find out for yourself. Find your own truth. Experiment!

 

[dualazmak]

The soundtrack of my life has been 'locked up' into this Stereo format, the music that I love, hold dear and have an emotional connection with. So I've decided to find "my way" in this puzzle of sound, to maximize my listening pleasure. To do so I've build my own speakers, changed up the room within the rules set by my spouse and started working/thinking and applying all I could come up with to really max out (my) listening pleasure. Dare I say I've accomplished more than I ever could imagine in advance.

To all: feel no need to believe me or anything I say. Just find out for yourself. Find your own truth. Experiment!

Really impressed since I am on almost the same direction!

As you may find here, the layout of my audio gears is always "within the rules set by my spouse"; I wrote that "I slightly modified the layout of the amplifiers and DAC8PRO on the large wide side-cabinet for nice usual/standard positioning of the completed 12-VU-Meter Array. This layout change was critical in getting approval and consent from our chief interior coordinator (my wife!);"
Fortunately, she has been always a very nice "auditor" for our audio setup, and also she loves enjoys listening to our beloved music tracks with me.

You wrote;
>So I've decided to find "my way" in this puzzle of sound, to maximize my listening pleasure.

I feel exactly the same in my audio project , and in my music listening enjoyments such as sharing here.

Thank you for your wonderful comments.

 

[Doodski]

Really impressed since I am on almost the same direction!

Lol. Like DuH! ( Slang: It means like, Yes, of course! ) (I will be using slang and colloquialisms.)

As you may find here, the layout of my audio gears is always "within the rules set by my spouse";

We see your spouse regulating everything and we wish we had a spouse like yours. (I am being silly...)

"I slightly modified the layout of the amplifiers and DAC8PRO on the large wide side-cabinet for nice usual/standard positioning of the completed 12-VU-Meter Array. This layout change was critical in getting approval and consent from our chief interior coordinator (my wife!);"

Of course...lol. I imagine that the VU meters have the best viewing angle now that your wife has tweaked the room.

Fortunately, she has been always a very nice "auditor" for our audio setup, and also she loves enjoys listening to our beloved music tracks with me.

That's the best part. I have enjoyed evenings at home alone with my sweetie pie just listening to music and those are memories that I shall keep.

 

[fineMen]

Think a bit harder, you're not quite getting it why I showed the video. Now his work has been upgraded to 'honourable' work, at least that's something worthwhile. I didn't get that same impression from you in your earlier replies. Well deserved though in the case of Dr. Griesinger.

O/k, my argumentation, dismissed all the way by all was like that:
- a stereo recording cannot be made "phase neutral" because of the inevitable recording process to begin with; multiple microphones, varying distances to distinct sound sources, mixing, panning etc.
- nearly all material, that the audiophile uses to enjoy his stereo (beware, not the music) was not recorded with 'phase' in mind; monitors are regularly not phase neutral
- a stereo replay (incl/ 'surround') is way different from natural hearing; e/g head related transfer function with two speakers for mono versus single source
Summary: stereo is not virtual reality, it needs an active process performed by the intellect (means: mind, not brain) of the listener to work

- all evidence for the relevance of phase in stereo replay is either fraudulent, plain wrong by error, misunderstood intentionally, and unintentionally, or gives clear limits for decades now, namely, expressed as a tolerable group delay of 1ms around 500Hz..2kHz, 2ms around 100Hz; such values are easy to achieve with conventional technology so much so, that nobody has to actually care about it
- nearly all proponents of a 'phase neutral' speaker have not the slightest clue what they are talking about; e/g take a visual representation of a "pulse" for reference as seen here again
Summary: phase distortion from a speaker's cross-over is a non issue despite the neurotic doubt of an audiophile who will never (!) tempt to just enjoy the music; it is exactly the same game as with cables and what have you, just--sorry to say, mislead incompetence and revolving dissatisfaction with something that no one actually needs, go figure!

- Dr. Griesinger distances his work from stereo, there is no connection at all

Think You about it: what is the quality of reflections with a natural single source in a room compared to reflections from two (!) sources (the speakers) that should mimic that same single source?

With the latter question I refer to Griesinger. But with stereo we are not halfway where Griesinger comes from. The timescale is different by an order of magnitude, the direction of reflections are different, reflections make chaotically ragged phase versus smooth and plain phase shift in cross-overs, etc pp and more and all.

 

[fineMen]

O/k, my argumentation, dismissed all the way by all was like that:
...
With the latter question I refer to Griesinger. But with stereo we are not halfway where Griesinger comes from. The timescale is different by an order of magnitude, the direction of reflections are different, reflections make chaotically ragged phase versus smooth and plain phase shift in cross-overs, etc pp and more and all.

To be very clear about it, I think it is a psychological thing. The audiophile, for me, runs around in a vicious circle. He is under the impression, that the reason for not enjoying the music was a lack of qualification with his actual specimen of a stereo equipment in exchange with sub-par recordings. So he doubts the engineers, accuses them of cutting corners etc. That is an easy move because the audiophile is not exactly an expert in technical things, let alone higher mathematics or science.

Actually he doesn't understand the inherent limitations of the stereo as a general technique. And he ignores his lacking need, in that he isn't interested in music at all.

The latter is the reason why there is no healing. To switch focus would do, but ... ignored.

That neurosis is the origin of this reiterated discussion of a settled topic. My opinion, not a statement of truth.

 

[Wesayso]

O/k, my argumentation, dismissed all the way by all was like that:
- a stereo recording cannot be made "phase neutral" because of the inevitable recording process to begin with; multiple microphones, varying distances to distinct sound sources, mixing, panning etc.
- nearly all material, that the audiophile uses to enjoy his stereo (beware, not the music) was not recorded with 'phase' in mind; monitors are regularly not phase neutral

Sure, it still depends on the recording as parts of it (like vocals etc.) may still be close mic recordings that can pop out from the background

- a stereo replay (incl/ 'surround') is way different from natural hearing; e/g head related transfer function with two speakers for mono versus single source
Summary: stereo is not virtual reality, it needs an active process performed by the intellect (means: mind, not brain) of the listener to work

Which is why I see it as my job to make the intellect work less hard, like neutral phase response and compensation for head related stuff etc.

- all evidence for the relevance of phase in stereo replay is either fraudulent, plain wrong by error, misunderstood intentionally, and unintentionally, or gives clear limits for decades now, namely, expressed as a tolerable group delay of 1ms around 500Hz..2kHz, 2ms around 100Hz; such values are easy to achieve with conventional technology so much so, that nobody has to actually care about it
- nearly all proponents of a 'phase neutral' speaker have not the slightest clue what they are talking about; e/g take a visual representation of a "pulse" for reference as seen here again
Summary: phase distortion from a speaker's cross-over is a non issue despite the neurotic doubt of an audiophile who will never (!) tempt to just enjoy the music; it is exactly the same game as with cables and what have you, just--sorry to say, mislead incompetence and revolving dissatisfaction with something that no one actually needs, go figure!

I don't think like the above, far from it. Just because the phase might not be preserved like we would have wanted, it's no reason for me to put other "time errors" on top of that... If a recording already has timing errors, and we don't even know how large or where, and we put the timing error from our speaker on top of that. How is that going to get me closer to any ideal? In my setup I've come across recordings where it mattered if I invert the stereo channels. It can even make the singer pop out from behind the music. So not all recordings will be done ideally. So I've noticed. But far more recordings are thoroughly enjoyable than are advertised by, dare I say it, audiophile notions.
I've come to enjoy more music, not less.

- Dr. Griesinger distances his work from stereo, there is no connection at all

He's worked on several components that were used during mixing etc. and was the creator of Logic 7, a system that was dedicated to take 2 channel music and make it work for surround. While other up-mixers like Dolby etc. used pretty simple steering, Griesinger has tried to maximize the listening pleasure of music taken from 2 channels.
I've never had the pleasure to listen to Logic 7 but did see favorable reviews of it compared to other up-mixers for music. Sadly in this industry, the best standard for something doesn't need to win/become the most popular choice.

Think You about it: what is the quality of reflections with a natural single source in a room compared to reflections from two (!) sources (the speakers) that should mimic that same single source?

With the latter question I refer to Griesinger. But with stereo we are not halfway where Griesinger comes from. The timescale is different by an order of magnitude, the direction of reflections are different, reflections make chaotically ragged phase versus smooth and plain phase shift in cross-overs, etc pp and more and all.

Didn't I say I absorb/avoid all the early reflections? In fact: they keep me from being able to hear what has been recorded. Griesinger wouldn't be a fan of early reflections in Stereo, Toole is the proponent of that. I side with Griesinger and rather have spaciousness and envelopment coming from later arriving lateral reflections/reverb.

I guess I can't call what I do Stereo or HiFi. It is My-Fi though, set-up for my personal enjoyment. Take from it what you will. I won't give a #$#$ anyway .
I'm much too busy enjoying the fruits of my labor. The advantage of the absence of those early reflections is that it can double as a system for HT.

I guess there are many roads to audio nirvana. I chose my own, unconventional, road and have no regrets... Find out what YOU like, not what someone else tells you to like.
I guess that makes me a strange bird on this site that seems to want to agree with all of Toole's teachings/findings. Like I mentioned, i'm grateful for all his hard work he presented us, but I see certain things in another light. As that leads me to more enjoyment.

 

[Wesayso]

To be very clear about it, I think it is a psychological thing. The audiophile, for me, runs around in a vicious circle. He is under the impression, that the reason for not enjoying the music was a lack of qualification with his actual specimen of a stereo equipment in exchange with sub-par recordings. So he doubts the engineers, accuses them of cutting corners etc. That is an easy move because the audiophile is not exactly an expert in technical things, let alone higher mathematics or science.

Actually he doesn't understand the inherent limitations of the stereo as a general technique. And he ignores his lacking need, in that he isn't interested in music at all.

The latter is the reason why there is no healing. To switch focus would do, but ... ignored.

That neurosis is the origin of this reiterated discussion of a settled topic. My opinion, not a statement of truth.

I can honestly say I don't resemble that.

 

[NTK]

O/k, my argumentation, dismissed all the way by all was like that:
- a stereo recording cannot be made "phase neutral" because of the inevitable recording process to begin with; multiple microphones, varying distances to distinct sound sources, mixing, panning etc.
- nearly all material, that the audiophile uses to enjoy his stereo (beware, not the music) was not recorded with 'phase' in mind; monitors are regularly not phase neutral
- a stereo replay (incl/ 'surround') is way different from natural hearing; e/g head related transfer function with two speakers for mono versus single source
Summary: stereo is not virtual reality, it needs an active process performed by the intellect (means: mind, not brain) of the listener to work

- all evidence for the relevance of phase in stereo replay is either fraudulent, plain wrong by error, misunderstood intentionally, and unintentionally, or gives clear limits for decades now, namely, expressed as a tolerable group delay of 1ms around 500Hz..2kHz, 2ms around 100Hz; such values are easy to achieve with conventional technology so much so, that nobody has to actually care about it
- nearly all proponents of a 'phase neutral' speaker have not the slightest clue what they are talking about; e/g take a visual representation of a "pulse" for reference as seen here again
Summary: phase distortion from a speaker's cross-over is a non issue despite the neurotic doubt of an audiophile who will never (!) tempt to just enjoy the music; it is exactly the same game as with cables and what have you, just--sorry to say, mislead incompetence and revolving dissatisfaction with something that no one actually needs, go figure!

- Dr. Griesinger distances his work from stereo, there is no connection at all

Think You about it: what is the quality of reflections with a natural single source in a room compared to reflections from two (!) sources (the speakers) that should mimic that same single source?

With the latter question I refer to Griesinger. But with stereo we are not halfway where Griesinger comes from. The timescale is different by an order of magnitude, the direction of reflections are different, reflections make chaotically ragged phase versus smooth and plain phase shift in cross-overs, etc pp and more and all.

For a change, I am agreeing (mostly) with @fineMen on this one. Phase "accuracy", in the grand scheme of things, isn't important.