Speaker time alignment, does it matter?

[BenB]

Not so easy. Did You check that the only parameter You changed was the phase / group delay / time alignment whatever You name what You are after? There were so and so many more or less focussed investigations and anecdotes which tell the contrary. So, better to double check.

Yep, I am sure, and perfectly willing to submit whatever I do for public scrutiny / verification (should there be a concerted effort that stems from this discussion).

 

[QMuse]

uh oh.

I'm looking for you to now explain why you are asserting that the presence of room reflections (which are obviously not coherent with respect to the sound coming directly from the speaker), make it impossible for a listener to hear the difference between a speaker with ideal transient response and a speaker where phase rotates through 360 degrees multiple times from low frequency to high frequency. It is obvious that this is the assertion you have made, but you didn't make any effort at all to back up this assertion. Instead, you included these graphs as though you expected the graphs would support this assertion, but all they really do is demonstrate that which is patently obvious and not the least bit subject to dispute, i.e., that reflections are not coherent with the sound directly from the speaker.

Please note also that when you say, "No wonder you can't hear ...", this statement takes your assertion as a forgone conclusion, thereby suggesting through innuendo that your assertion is an established fact beyond dispute. This is argumentatively impolite.

When you time align a speaker you actually time align a direct wave over it's frequency range. Now imagine 10 or 20 of those same waves coming 1 ms away from each other and each summing to the original direct wave coming from the speaker. That is what you will actually be hearing in a room where reflections occur and that is what will destroy the beauty of the time aligned direct wave that you would be hearing in anechoic chamber or over the headphones. When that happens our ears/brain are not able to distinguish early reflections from direct sound and any effect of time aligning is lost. As the same process happens when we are listening to other person speaking in the room we are simply accustomed not to care about the mess reflections are causing so we don't recognise time aligned waves as such thing doesn't exist when listening sounds in a room. Many studies have been made on that topic so educate yourself before making any further claims.

 

[NTK]

Yep, I am sure, and perfectly willing to submit whatever I do for public scrutiny / verification (should there be a concerted effort that stems from this discussion).

I generated some test signals on the audibility of phase differences a while back, and posted them in this post.
https://www.audiosciencereview.com/forum/index.php?threads/phase-shift.9602/#post-255460

 

[KaiserSoze]

When I did that test, I tried to get forum members to repeat it (might have been the madisound forum, or PE... I can't remember at this point), but I didn't get much traction. This forum is a lot more technical, so it may go over better here. I can generate all-pass filters to mimic the phase distortion of various crossovers, and post those. I could also filter some short audio files and post in a lossless format, but that opens up a whole discussion about what to include. I don't have that much free time to commit to this. It would be great to get some help from others if they wanted to provide instructions for downloading foobar (or something similar) and installing the appropriate plug-ins. Also, anyone with matlab or octave (which is free) can perform the filtering... there are probably many others programs capable of it as well. If there is substantial interest, I could certainly support an effort to bring others into this kind of testing, though my time is somewhat limited due to numerous responsibilities and other projects.

What support would you need to make it possible to perform this investigation yourself?

I do think that knowing the impact of phase distortion is important for audio consumers and producers, so that engineering efforts can be targeted at the right areas. Engineering is the optimization of compromises, and we have to know which ones we can get away with, and which ones we can't.

Ben, I like this idea very much, and I think that if it is done well, with the participation of this forum and with the fundamental premise of using high-quality, high-bandwidth headphones, it would have the potential of becoming a definitive experiment for future reference. But I'm not presently in a position where I would have the time this would take. Possibly before the end of this year, but I couldn't even guarantee that. Also, I fully expect that I would end up being a source of frustration for you, with you ending up doing all the hard work that I couldn't do because I'm too much of a dummy. So for me, it makes sense to keep this in mind as a potential project for a future date. In the meantime, my starting point for doing the required research will be with those all-pass filters.

 

[KaiserSoze]

When you time align a speaker you actually time align a direct wave over it's frequency range. Now imagine 10 or 20 of those same waves coming 1 ms away from each other and each summing to the original direct wave coming from the speaker. That is what you will actually be hearing in a room where reflections occur and that is what will destroy the beauty of the time aligned direct wave that you would be hearing in anechoic chamber or over the headphones. When that happens our ears/brain are not able to distinguish early reflections from direct sound and any effect of time aligning is lost. As the same process happens when we are listening to other person speaking in the room we are simply accustomed not to care about the mess reflections are causing so we don't recognise time aligned waves as such thing doesn't exist when listening sounds in a room. Many studies have been made on that topic so educate yourself before making any further claims.

This is the exact same assertion you already made. As for my "further claims", all I did was relate a personal experience. YOU are the one who has made claims, and as such the onus is on you to provide the research to back up your claim. I like BenB's proposal. If you can refer us to existing research that conclusively demonstrates that multiple full cycles of phase rotation from low to high frequency will be undetectable in a typical listening room, then by all means spare us the effort and produce the research. PLEASE NOTE, though, that if you do this and provide research that proves something that is loosely related to the specific question at hand but not exactly the same thing, i.e., something that is concerned with our ability to resolve sounds closely spaced in time into distinct sounds vs. a single sound and not concerned very specifically with the specific question at hand, that if you do this, you will have no grounds to protest if I do not treat you with kid gloves.

 

[GelbeMusik]

PLEASE NOTE, though, that if you do this ... that if you do this, you will have no grounds to protest if I do not treat you with kid gloves.

What is all that em-phasis about? Another topic that raises doubt in the real-ness of stereo re-production, at least subtle, no preference ever made it into the urban ledgend, just some change that is more felt than clearly recognized, as far as people tell?

I dare to say, the less competent the design of e/g a speaker, the more it will suffer from overdrive. As audioenthusiasts nearly always prefer tiny shoe-box speakers of magically "revealing" powers, the phase matters! It determines the cone excursion, which is so delicate. Good speakers? I would say very bad speakers, just right for our audiophobic friends.

These guys don't search for solutions, they wanna spoil the fun of all others.

If You need it, just do it! Use digital correction, do it! WTF!

 

[MZKM]

As best as I could tell, what that Mr. Brunhaver is saying is that even if physical alignment of drivers is used to achieve phase coherency in the overlap region of two drivers that interface, this won't eliminate the overall rotation in phase that occurs in a speaker from low frequency to high frequency. So what? Does he mean to imply that since the overall rotation in phase cannot be avoided through physical alignment of the drivers, that there isn't any benefit to making the two drivers phase coherent in the overlap? The impression I'm left with is that he doesn't understand the reason that with most speakers the tweeter is vertically aligned with the rear of the woofer cone. This is done for reasons that have to do with the proper summation of the two individual wavefronts within the overlap frequencies, such that the main lobe, for any frequency within the overlap, will extend along a horizontal plane, rather than tilt up or down. If the lobe tilts up or down, then the tonality of the speaker will be different at different distances from the speaker. In order to avoid tilting of the lobe, it is necessary for the two individual wavefronts to be phase-coherent, not merely at the exact crossover frequency, but throughout the overlap region. Vertical alignment of the two drivers is one aspect of achieving this goal. It might not be essential to do this in order to achieve this goal, but when it is done, it is done toward achieving this goal, and it makes perfect sense, irrespective of the fact that there will still be an overall phase rotation from low to high frequency.

I mean, he is the one that convinced Paul to ditch Arnie Nudell’s prototype for a new design where the midrange is physically behind the tweeter:

 

[KaiserSoze]

I mean, he is the one that convinced Paul to ditch Arnie Nudell’s prototype for a new design where the midrange is physically behind the tweeter:
View attachment 69910

Is this supposed to be corrected in the crossover, i.e., with an all-pass network?

 

[GelbeMusik]

Yep, I am sure, and perfectly willing to submit whatever I do for public scrutiny / verification (should there be a concerted effort that stems from this discussion).

Please do not do that. Since it is a quite common pattern with this. Some people tell You about some extra ordinary experience they had. You tell, that it cannot be. But as the experience was so striking, an enlightment so to say, people insist. The more You grab out reasonable arguments, the more those people use verbal aggression against opponents, but confirmation for everyone who is willing to listen to their ourrageous claims.

Always it comes to the point, where You find Yourself in a position to defend Your point of view against ever worsening accusations. As if it was You to approve their reality!

Why don't these guys reach out to investigate their point themselves, and possibly win the Nobel prize? In many cases it is due to lacking methodology, they simply cannot do, because the appropriate skill is (very) missing. And one might argue, the final motivation for actually putting their own claims to the test, is missing too.

Again this thread is full of mislead assumptions, a severe misunderstanding of nearly everthing this possibly could be about. There is actually not a hint of a concept that would bring that "something" into any workable shape. I tell You, once You might have done Your tests of whatever, and it wouldn't please, it would be dumped to the garbage can. Without questions, without grace, heartlessly. And then they leave, maybe to another place.

There are so many investigation already done, with top notch equipment, with a wide panel of subjects, with all control of everything, a huge amount of background education, long experience, not the least some peer review, in short, big money, lots of time, how could You re-do that all at once? It would be a pitty to see You fail on this impossible task, hunted down.

 

[QMuse]

This is the exact same assertion you already made. As for my "further claims", all I did was relate a personal experience. YOU are the one who has made claims, and as such the onus is on you to provide the research to back up your claim. I like BenB's proposal. If you can refer us to existing research that conclusively demonstrates that multiple full cycles of phase rotation from low to high frequency will be undetectable in a typical listening room, then by all means spare us the effort and produce the research. PLEASE NOTE, though, that if you do this and provide research that proves something that is loosely related to the specific question at hand but not exactly the same thing, i.e., something that is concerned with our ability to resolve sounds closely spaced in time into distinct sounds vs. a single sound and not concerned very specifically with the specific question at hand, that if you do this, you will have no grounds to protest if I do not treat you with kid gloves.

Every week there is a guy on this forum claiming that time alignement matters and instead of providing proof for that claim when told it doesn't he requires proof that it doesn't.

Various research papers from Toole and others have been quoted and linked at least dozen times so on this forum so use Search button and educate yourself instead of writing the same nonsense that has been written many times before.

 

[GelbeMusik]

I mean, he is the one that convinced Paul to ditch Arnie Nudell’s prototype for a new design where the midrange is physically behind the tweeter:

Exactly, nothing helps. A LASER like phase coherence would ask either for an infinitely small radiator of infinitely small efficiency, or for a bubble with a homogenious drive over all its surface and enough damping to prevent from partial movement. Or someone finds a solution in quantum mechanics of course. ( I suggest that string theory is secretly looking for that. )

 

[Deleted member 16502]

Here is an article about phase distortion audibility that I was provided with by a kind forum member when I asked the same question some days ago.

 

[KaiserSoze]

Please do not do that. Since it is a quite common pattern with this. Some people tell You about some extra ordinary experience they had. You tell, that it cannot be. But as the experience was so striking, an enlightment so to say, people insist. The more You grab out reasonable arguments, the more those people use verbal aggression against opponents, but confirmation for everyone who is willing to listen to their ourrageous claims.

Always it comes to the point, where You find Yourself in a position to defend Your point of view against ever worsening accusations. As if it was You to approve their reality!

Why don't these guys reach out to investigate their point themselves, and possibly win the Nobel prize? In many cases it is due to lacking methodology, they simply cannot do, because the appropriate skill is (very) missing. And one might argue, the final motivation for actually putting their own claims to the test, is missing too.

Again this thread is full of mislead assumptions, a severe misunderstanding of nearly everthing this possibly could be about. There is actually not a hint of a concept that would bring that "something" into any workable shape. I tell You, once You might have done Your tests of whatever, and it wouldn't please, it would be dumped to the garbage can. Without questions, without grace, heartlessly. And then they leave, maybe to another place.

There are so many investigation already done, with top notch equipment, with a wide panel of subjects, with all control of everything, a huge amount of background education, long experience, not the least some peer review, in short, big money, lots of time, how could You re-do that all at once? It would be a pitty to see You fail on this impossible task, hunted down.

Another purely toxic post by GelbeMusik. The manifest intent is to sow disharmony among other forum participants. It adds nothing whatsoever to the discussion, and is written in style so utterly bizarre that I would think it was the output of a robot language translator except for the fact that there are parts of it that are written naturally.

 

[KaiserSoze]

Every week there is a guy on this forum claiming that time alignement matters and instead of providing proof for that claim when told it doesn't he requires proof that it doesn't.

Various research papers from Toole and others have been quoted and linked at least dozen times so on this forum so use Search button and educate yourself instead of writing the same nonsense that has been written many times before.

Wow. I will point out to you for the second time that I did not make any claim of that sort. It was YOU who made an assertion, and as such the only person here who has any obligation whatsoever to back up their assertion with evidence is YOU, not me. It is BIZARRE that you do not get this. EXCEEDINGLY BIZARRE, in fact. It is as though you believe that you are permitted to do this because your opinion is the majority opinion. This isn't how it works in any orthodox scientific setting. The person who has made an assertion (you) is the person who has an obligation to back it up with evidence, irrespective of whose point of view is or isn't in line with the majority view. If your mentality was anything close to that of a real scientist, you would know this full well and would not be trying to flip it around on me and insist that I have an obligation to back up an assertion that you only imagine that I made.

 

[Thomas savage]

Less of the personal beef please , if this discussion is not of interest consider not participating. I know , revolutionary thought lol

This is a audio forum, you can expect theses sorts of things to be discussed , sometimes often.

 

[GelbeMusik]

Here is an article about phase distortion audibility that I was provided with by a kind forum member when I asked the same question some days ago.

Did You notice that back and forth an allpass filter was identified with lesser confidence, the bigger the phase lag was? I read the original publication ( yes, I can ):

http://mue.music.miami.edu/wp-content/uploads/2013/10/MastersThesisDaisukeKoya.pdf

It is public to the public, other than some AES internals.

Read section (5. Results and Discussion). That is what I would call a clear concession of a NULL result. The tests do not in any way lead to a substantial conclusion. All what is left are speculations regarding some other mechnisms in the "auditory system", take note, which were not considered when designing the tests.

"Conducting research of broad test-signal scope and experimental design practicality
resulted in limited results. Obviously, more refined research utilizing a greater signal
variation base (i.e., more frequencies for sawtooth waves across frequency spectra)
and phase distortion levels are necessary to ascertain more accurate permissible levels
of phase distortion for these signals."

"The human auditory system was found to be extremely tolerant of even gross
phase distortion effects. Although the impulse test signals. ... Improved irradiation methods,
such as the use of phase-equalized loudspeakers in an anechoic environment, may
also aid in ascertaining more accurate permissible levels."

Why is it so hard, seemingly, to give up an idealistic requirement regarding the signal, despite the fact that even with compromises the information is there completely?

Additionally it is impossible to maintain phase anyway. Spatially extended sources would change phase relations with angle, e/g a drum kit, piano, human voice. There is directivity, and so there is phase ondulations. Same with microphones, intrinsically. Same with the mixing guy at his desk, and his maybe "timed" speakers--he is going to move sometimes. That would necessarily spoil all the effort on "time". And the same at home.

The best "time alignment" one could have is to listen to music, when You don't think of possible imperfection of that holy device in front of You. Take a time off and just enjoy the music.

 

[BenB]

I'm sick in bed, so took the time to make some impulses (for the 2nd time in my life). It was a little harder than I remembered... my first attempts had about 1/10th dB magnitude ripples, which could possibly be more audible than the phase. In the end, I was able to push that to about 1/100th dB or less. It's always possible that I have done something wrong, and that things look horrible at some resolution other than the ones I've used to create and analyze the filters. Regarding the phase, the filters are the combination of the allpass that generates the phase distortion, along with a fractional sample delay filter, which is required to make the nyquist bin real. The files are 16 bit 44.1 kHz waves, which should match what's most common. I don't know if convolver programs like foobar will be happy with impulses that are in a different resolution than the music.

It would be great to have another contributor check these for correctness. There's 4th order at 100, 300, 1000 and 3000 Hz. If there's interest, I can make 2nd order filters as well.

 

[QMuse]

Less of the personal beef please , if this discussion is not of interest consider not participating. I know , revolutionary thought lol

This is a audio forum, you can expect theses sorts of things to be discussed , sometimes often.

No problem, I'll see my self out, as it seems on this forum moderating doesn't seem to imply cutting off the futile discussions that happened many times before, but in the name of "democracy", it is about letting as many new users to repeat the same bullshit all over again. Anyway, as democracy gets easilly abused with the freedom to express ones opinion, even when that opinon is completely subjective BS, let's see how it works:

For example:

"Yet we are told by many of the smartest technical people in the industry that there isn't any evidence that time/phase coherency is audible except with respect to achieving a flat response through the crossover regions (in which case it is really the phase coherency that matters and time coherency is merely a means to that end).

For me it is difficult to let go of my early experiences. In the early '70s, when I was 19 or 20, in a big old record store that also sold some loudspeakers, I heard a speaker that I'd never heard of. It was immediately apparent to me that there was something different about the speaker I was listening to. This was before college, when I was very technically naive. The music that was playing had some percussion instruments, and to me it was apparent that this speaker was reproducing those sounds in a way that was more realistic than I was used to hearing through amplified loudspeakers. The difference was so stark that my memory of the experience including my reaction remains vivid. "

So yeah, in the name of the "freedom of the speech" lets allow everyone the right to speak their mind, without warning them to think before they speak, or to search the forum before they excersise their right to speak, as it may have been discusse before so one can learn something before speaking.

Or we can let everyone speak never the less, in the name of democracy, as with this forum it is all about quantity and not the about quality.
On the other hand, when time comes to sell it, it may indeed be about number of hits and not about number of wise thoughts, right?

 

[Thomas savage]

On the other hand, when time comes to sell it, it may indeed be about number of hits and not about number of wise thoughts, right?

Iv no financial interest in ASR , this is not a democracy . So as I'm in charge this statement of yours looks rather silly.

Now there's people here discussing time alignment, not for the first time and likely not the last.

Personally I'm of the opinion it's not vital in the absolute sense , but if we can investigate it and test audibility out that's got to be a worthwhile thing to look into . I'm hardly going to shut down the discussion or ban all talk of it as you so bizarrely suggest .

 

[GelbeMusik]

I'm sick in bed, so took the time to make some impulses (for the 2nd time in my life). It was a little harder than I remembered...

There was an investigation already, cited by somebody else, peer reviewd, to some degree by Toole. What are You aiming for?

A third point, which I feel is quite important: today, in contrast to the 70s / 80s /90s we all have the opportunity not only discuss this malicious topic to death. There is light at the end of the tunnel. Change Your perspective. With not so costly software it is possible to phase / time correct every georgious stereo "system". If You want it, there You have it! What is the use in discussing this topic anymore?

So dear time people, just apply an EQ to Your liking, and there You go. Case closed.

Now back to topic: Joanna Newsom, The Sprout And The Bean--what do You think the position at which the string is plugged changes 'phase'? And the voice, the most square wave rendition of a human voice, isn't it?