Importance of impulse response

[Multicore]

I'm not sure I get your point, but what I was trying to say is that I have no interest in manipulating the recording on playback to create an artificial soundstage. I know that some sound engineers may also manipulate things, or streamers (usually video) also may add spatial effects.

The stereo standard and market expectation forces it. For example, mixing any multitrack recording to stereo forces them into having to make these arbitrary aesthetic choices. (See my previous two posts in the last hour above.) Often what they do is so annoying that I use my own "mono button" (e.g. in APO Eq mixing 0.5xL + 0.5xR to each output channel) to defeat it so that I can better concentrate on what the musicians did prior to the addition of these stereo effects.

To be clear, I am not denying that a good stereo recording of a singular acoustic event played back on a well controlled system cannot produce a satisfying experience.

 

[fineMen]

Thanks I try to

There is no pay wall for the article I linked, down at the bottom there is a link to the full paper on the University's site. Do you mean another paper that is pay only?

I think it was reference #9 in the paper You linked, the survey regarding HRTF with which the time reversal was introduced. The abstract of #9 doesn't give a clue why time reversal may be beneficial? Or was it something else in relation to the modelling of HRTF in the first place? Fll text has to be payed by a considerable amount. At least the authors of Your link don't explain anything, despite it being upmost crucial.

It makes sense when trying to test if waveform accuracy matters for audibility, if you can listen to the same thing forwards or backwards and have it sound the same then any flaw in it is inaudible. Some things were audible which is evidence that ...

Exactly the reasoning behind Your somehow reiterated statement is what I don't get. I'm a fool sometimes. But I think that is in order once in a while. It doesn't make any sense to me for the time being, sorry. If You explain it to me successfully, I'll give You a comprehensive lecture on Special Relativity for free using only primary school mathematics (if desired).

You've lost me on where the figure of 8ms is coming from at what frequency.

Graph #11 c), presumably a 'measured' loudspeaker instead of modeled; but who knows? Anyway, I published the timely behaviour of my current speaker boxes in my room. They were never intended to be somehow time correct; regular as can be, one might say, due to audiophile (I like music more) sloppyness here and there, even sub standard in regard to nearly all stylish detail, e/g no waveguide, sharp rectangular corners, not counter sunk drivers of cheapest prevenience, flimsy enclosure, what have You ... a junkyard of a speaker. Still: perfect.

 

[fluid]

I think it was reference #9 in the paper You linked, the survey regarding HRTF with which the time reversal was introduced. The abstract of #9 doesn't give a clue why time reversal may be beneficial? Or was it something else in relation to the modelling of HRTF in the first place? Fll text has to be payed by a considerable amount. At least the authors of Your link don't explain anything, despite it being upmost crucial.

The full paper is here
https://www.researchgate.net/public..._head-related_transfer-function_phase_spectra

Exactly the reasoning behind Your somehow reiterated statement is what I don't get. I'm a fool sometimes. But I think that is in order once in a while. It doesn't make any sense to me for the time being, sorry. If You explain it to me successfully, I'll give You a comprehensive lecture on Special Relativity for free using only primary school mathematics (if desired).

"the time reversal produced the maximum phase difference while simultaneously keeping the magnitude response unchanged"
By comparing forwards to backwards gives the greatest range of phase change without a change in magnitude.

Graph #11 c), presumably a 'measured' loudspeaker instead of modeled; but who knows? Anyway, I published the timely behaviour of my current speaker boxes in my room. They were never intended to be somehow time correct; regular as can be, one might say, due to audiophile (I like music more) sloppyness here and there, even sub standard in regard to nearly all stylish detail, e/g no waveguide, sharp rectangular corners, not counter sunk drivers of cheapest prevenience, flimsy enclosure, what have You ... a junkyard of a speaker. Still: perfect.

Perhaps the companion paper sheds more light on the specifics of the modelling
https://acris.aalto.fi/ws/portalfil...Equalization_on_Loudspeaker_Responses_AAM.pdf

 

[fineMen]

The full paper is here
https://www.researchgate.net/public..._head-related_transfer-function_phase_spectra

Cute, the time reversal is used as a, may I become colloquial, stinky rotten fish in between all the cake. They try to model a more generalizable head related transfer function (HRTF) in order to feed some plug-in headphones with it. To make the experience of p/i-phones more natural. Good thing, worth my taxes! Think of people with impaired hearing who need and shall get aid. On the other hand, I would even grant them a subjectively measured HRTF for the necessary equalization.

(Scientific) question was, if the HRTF is just amplitude and frequency independent time delay or is there is a further phase shift left./.right to be considered. And if so, which would be a good (and easy) model to replicate that particular phase shift. The "time reversal" is the stinky fish in that (presumably) for sure it has nothing to do with the real thing. So, if people are willing to accept even the stinky fish--plus proper time delay and amplitude, phase is irrelevant. The test was logically performed 'binaural' with two ears at the same time. With 'monaural' people didn't get any (!) clue what is what.

Okey dokey. Now it is Your turn to tell, how that applies to the phase response of a modelled single speaker box, listened to monophonic over not linear, not corrected, presumably not even evaluated headphones. What does the stinky fish do in all the tests? For the time being I'm so super arrogant, I would rather assume the authors fell in a fallacy. Please prove me wrong. What am I missing? What didn't these guys explain?

Perhaps the companion paper sheds more light on the specifics of the modelling
https://acris.aalto.fi/ws/portalfil...Equalization_on_Loudspeaker_Responses_AAM.pdf

Yep, 8th order FIR filters. Planning for the future on Mars? And again fallacy in some points, but off topic here.

Would You mind concluding this side path of the thread with a not necessarily lengthy but still understandable explanation what went wrong on which side?

 

[fluid]

Would You mind concluding this side path of the thread with a not necessarily lengthy but still understandable explanation what went wrong on which side?

I would if I could but I find it very hard to understand your writing. Like all research, read it, assess it and decide if it has any value to you.

 

[fineMen]

I would if I could but I find it very hard to understand your writing. Like all research, read it, assess it and decide if it has any value to you.

Sorry, its not my writing for sure. Even if in case was actually bad. Better we all read and understand the article(s). Then after we together may understand the question I asked. And maybe there is an answer. Simple, right?

Why is the time reversal used in this investigation:
https://research.aalto.fi/en/publications/audibility-of-loudspeaker-group-delay-characteristics ?

Because the reference (#9) in that article to another article doesn't reveal why:

https://www.researchgate.net/publication/12962379_Sensitivity_of_human_subjects_to_head-related_transfer-function_phase_spectra

To the contrary I assume. Or is it just another case, that we wave with papers because the summary ('abstract') remotely relates to high-end audio?

I told You, I'm a scientist by education. I quickly get serious with things like this. But I work on it to hopefully become a better person sometimes in the future.

 

[NTK]

How much clearer does it need to be?

 

[JanesJr1]

The stereo standard and market expectation forces it. For example, mixing any multitrack recording to stereo forces them into having to make these arbitrary aesthetic choices. (See my previous two posts in the last hour above.) Often what they do is so annoying that I use my own "mono button" (e.g. in APO Eq mixing 0.5xL + 0.5xR to each output channel) to defeat it so that I can better concentrate on what the musicians did prior to the addition of these stereo effects.

To be clear, I am not denying that a good stereo recording of a singular acoustic event played back on a well controlled system cannot produce a satisfying experience.

Then we completely agree! On electronica and most pop, I take things as-is, for good or bad. But I also listen to classical, folk, a little jazz, and a little country. I just like to tweak the you-are-there fidelity of the better recordings. I know my brain is the sound-processor-in-chief for soundstage, but I can tickle it in the right direction during playback often enough to be worth the effort. On the hardware side, we have to be objective. On the listening side, subjective is king! YMMV.

 

[gino1961]

is there a commercial speaker with a SOTA response to impulse ? or at least a single transducer
My feeling is that passive xovers tend to mess up things very badly ... less so active xovers ? this would be very interesting for me to know

 

[NTK]

is there a commercial speaker with a SOTA response to impulse ? or at least a single transducer
My feeling is that passive xovers tend to mess up things very badly ... less so active xovers ? this would be very interesting for me to know

Here are the step responses of Kii Three as measured by Erin.

Kii Audio THREE Review

Kii Audio THREE 2-Way Studio Monitor Review

www.erinsaudiocorner.com

The first plot is the DSP "phase corrected" response. The second is what one would expect from a minimum phase passive crossover for a 3-way speaker.

 

[gino1961]

Here are the step responses of Kii Three as measured by Erin.

Kii Audio THREE Review

Kii Audio THREE 2-Way Studio Monitor Review

www.erinsaudiocorner.com

The first plot is the DSP "phase corrected" response. The second is what one would expect from a minimum phase passive crossover for a 3-way speaker.

Hi ! thanks a lot for the very valuable reply Can you confirm about passive crossovers negative influence on the dynamic behaviour of a speakers ?
i am deciding to go or not with an active crossover speaker (and powered)

 

[NTK]

Hi ! thanks a lot for the very valuable reply Can you confirm about passive crossovers negative influence on the dynamic behaviour of a speakers ?
i am deciding to go or not with an active crossover speaker (and powered)

The prevailing belief is that human hearing is highly insensitive to phase. For speakers with DSP, it costs nothing to correct for phase, and so it is often done. IMHO "phase correctness" is low on the list of things I'd consider important.

 

[fineMen]

Then we completely agree! ... But I also listen to ...know my brain is the sound-processor-in-chief ...

So You understand: its neither the 'signal' nor the 'information' to the 'hearing system'--it is Your mind to de-code music as an abstract structure without any connection to real things. Get a telephone call and win the Nobel prize. 'Won't believe, because the 'impulse resonse' on the line wasn't right?! So I know my beloved audiophiles gone 'science'.

Sorry, I'm going to treat myself with an additional dose of 7ties Hawkwind. Godspeed You.

 

[fineMen]

I have seen a lot of people here say that impulse response is not relevant, and that basically only frequency response matters.
This confused me because I happen to use Eclipse single driver speakers, which I like a lot and I indeed think they sound really transparent like they claim, and their whole philosophy is basically designing for good impulse response. Is it just BS?
Also I always thought that it makes sense that a smaller driver would be faster and thus sound faster, due to it being lighter.
Some people say that if it can reproduce 20Khz its fast enough which also makes sense. Is that actually true? and if it is, is fastness really FR related too, because it really feels like a different "sensation" if that makes any sense.

Your initial post spiked a lot of controversy. In regard to Your last sentence, it doesn't make sense. Is that enough? Some people wave "scientific papers" that are at the same time b/s and logically not understood. It has been a long battle about so called 'impulse response'. Truth is, all claims of that being relevant for enjoying music were debunked as b/s. There are pathological designs like the Klipsh Horn, the big one which actually has problems. But for common domestic speakers the 'time response' is a non issue.

No, a smaller speaker is not faster and so on. There is no thing like fast sound. That is true. Just the truth. Marketing is plain lying at You, that simple. Another aspect of reality. Welcome!

 

[ernestcarl]

Is there a way for the graph to look like Kimmosoto's graph of ETC, Step response in REW? Is it as simple as choosing ETC and Step and thats it?

VituixCAD graphs tend to look a lot more dense… yeah. In REW, what would probably make things easier is if you find a model(s) of known good speakers and how they measure in various rooms.

Maybe open two separate instances of REW so you don’t have to go back and forth in-between the “currently selected” measurements so much.

Compare those to your own graphs. We know that rooms can sometimes mangle the final measured response at the MLP incredibly bad… but what we probably would really want to know is how the response without the room (anechoic or however as much as possible “quasi-anechoic”) compares to one with the the room and distance at the actual listening position.

When I said your impulse response graph looks weirdly mangled — a DIY tri-amp setup? — you should maybe try to figure out where it’s coming from. And, yeah, I’d cycle through all the other display view settings and individual driver measurement overlays, and not just look at the magnitude frequency response graph alone, I think more so esp. because it’s DIY.

Oh, and don’t get hung up on the idea that a speaker has to be linear phase or look like its step response has the profile of one that is a requirement for it to sound any good.

 

[ernestcarl]

In-room frequency response examples from full IR swept sine measurement data can be hard to come by... however, here's one mdat file compilation I found over gearslutz/gearspace today:

Bunch of Gearslutz REW results in one .mdat file - Gearspace.com

A question that gets asked a lot on this forum is: “How good are my REW measurements?”. And the way I’ve always approached this is to compare my own room results with those of other forum members, especially if they share a similar room size. I think it’s

gearspace.com

Hmmmn... and there's always the few old "sample data" measurements in Room EQ Wizard's own website which I found quite valuable for comparison with my own and in learning REW in the past.

I'll attach two of mine (front mains and subwoofer) in here too, yet again -- eh, cause... why not? It's the same-same speakers used in my couch bass managed setup example I've shown here and elsewhere: https://www.audiosciencereview.com/...etation-and-understanding.38984/#post-1373627


*things have been positioned as best as possible (measurement-wise to get better results for these in-room sweeps).

Mind you, not perfect measurements at any one point in the room or even in the limited spread across the listening couch itself... but overall I like the objective final result (and subjective listening as well) -- esp. at my main listening position which really is the most important thing anyway.

 

[fluid]

Or is it just another case, that we wave with papers because the summary ('abstract') remotely relates to high-end audio?

Not on my part, I posted a link to some research that I thought relevant to a question being asked

I told You, I'm a scientist by education. I quickly get serious with things like this. But I work on it to hopefully become a better person sometimes in the future.

I don't have a problem with getting serious, but the answer in this case is so obvious I struggle to see what an educated scientist is having trouble understanding.

 

[fluid]

The prevailing belief is that human hearing is highly insensitive to phase.

In a broad general sense I think that is true. In my own experiments there is a very obvious difference in sound at lower frequencies when phase is manipulated. Exactly what is at play that causes the difference is still not clear to me, but there is a lot of research that points to the theory of temporal hearing being more correct at lower frequencies than it is at higher ones.

IMHO "phase correctness" is low on the list of things I'd consider important.

I agree with this too but once you have started to deal with some of the bigger problems, the lesser ones can become more obvious. I have often found the difference between good and great wasn't actually all that much.

 

[Tangband]

I have seen a lot of people here say that impulse response is not relevant, and that basically only frequency response matters.
This confused me because I happen to use Eclipse single driver speakers, which I like a lot and I indeed think they sound really transparent like they claim, and their whole philosophy is basically designing for good impulse response. Is it just BS?
Also I always thought that it makes sense that a smaller driver would be faster and thus sound faster, due to it being lighter.
Some people say that if it can reproduce 20Khz its fast enough which also makes sense. Is that actually true? and if it is, is fastness really FR related too, because it really feels like a different "sensation" if that makes any sense.

We seems to have different sensitivity to group delay depending on the frequencies we are talking about.
The Genelec paper says this :


”Loudspeaker impulse responses were studied using a paired-comparison listening test to learn about the audibility of the loudspeaker group-delay characteristics. Several modeled and six measured loudspeakers were included in this study. The impulse responses and their time-reversed versions were used in order to maximize the change in the temporal structure and group delay without affecting the magnitude spectrum, and the subjects were asked whether they could hear a difference. Additionally, the same impulse responses were compared after convolving them with a pink impulse, defined in this paper, which causes a low-frequency emphasis. The results give an idea of how much the group delay of a loudspeaker system can vary so that it is unlikely to cause audible effects in sound reproduction. Our results suggest that when the group delay in the frequency range from 300 Hz to 1 kHz is below 1.0 ms, it is inaudible. With low-frequency emphasis, the group delay variations can be heard more easily.”

————

1 ms soundtravel is 34,3 cm in 20 degree celcius. 1 ms is also the wavelenght of 1 KHz . This should have consequences when using different crossover frequencys, regarding the distance between the drivers that cant be to big.

 

[Tangband]

Other studies have shown when you have the exact same speaker with the exact same crossover slopes etc, the linear phase version is mostly preferred over the common allpass phase version. The more crossover points you have at lower frequencies (<1kHz) the stronger the preference. Subwoofer XO at ~80Hz is especially bad for "speed" and "compactness" of bass transients.

Remember, "transient" does NOT mean a sharp and short pulse here, rather it means a short but tonal burst of just a few cycles of a sine wave with a smooth envelope, often called "blips". Those are even standardized, by now (CEA-2010 Burst, 6.5 cycles, Hann window envelope). Phase distortion now manifests itself in different arrival times of those bursts at different frequencies (the lower ones coming later, typically) even though they started at the same time (or had their "center of gravity" aligned) in the source signal. And that's what we can perceive in a direct comparison, some more than others...

Thanks for this teaching.