what data? come again?
Oh come on, SY! Floor conduction is a pretty well known issue, not some ooga booga that no one has ever studied before!
First a simple empirical test anyone can do:
place your feet firmly on the ground, then play a recording with big bass percussive whacks, spaced apart so you can notice individual whacks.... and put just a little attention to which one you notice first.
Most people, assuming they have enough sensation in their feet, will readily FEEL the conducted wave first.
If you're feeling it, you are also perceiving it, which means you are pre-alerted to the bass transient right? With speakers at 3m or so, this'll be about 7 mS or so before the acoustic wave arrives.
Jeez, doesn't the above seem self-evident?
But maybe the above needs a DBT test to see if the subjects can clearly notice whether their feet are on the ground or not.
OK, so now you want measured data? DIY !! It's easy!
Put accelerometers at the floor under the speaker, and another under your feet at the listening location at 3m or so and measure it. Use a digital scope and then look at the difference in vertical amplitude between triggering signal and what arrives at your feet. Time gate it for various times after trigger, maybe between 5 and 40 mS, and look at them waves.
For transverse waves you can mount the accelerator on a block and secure the block to the floor so the accelerometer is at 90 degrees to the floor. Turn the block 90 degrees to measure lateral transverse waves.
Look, I'm not interested in providing proof for things that are evident from logical deduction. Especially with the rigor demanded by some who presume to be authorities because they have conducted much research in other fields.
However...
about 30 years ago I did some tests on an old suspended floor... using single shot filtered pulses with a digital scope, averaging results to increase s/n ratio, and quite was shocked to see just how little attenuation there was, and even more when I changed the time gating to see how additive interference from reflections, coupled with the floor's resonances were 20 to 30 dB higher in amplitude at the feet than at the origin (at some frequencies).
As for what actually arrives at the inner ear and its audibility? Since you like doing research, I refer you to the medical studies that exist on bone conduction.
Here is a study about feet to ear hearing, where the research is done on elephants, with some parallels drawn to the human auditory system:
Research Labs
When I get the time, I might try to do a comparative study with accelerometers on the feet and the bones in front of the ears just to be able to see how much of is getting through, unless I can find a study which has already been done. But I don't think it's very useful to debate whether it is perceptible or not, that part is pretty well established. and rigorously so.
Where it comes to being able to detect vibration through the floor, it's already QED, but I haven't generated or seen any studies which define by how much.
Look, SY, your bias in favor of doing exhaustive research with scientific rigor is fine, and very much appropriate for publication in scientific journals. But this is not such a publication, and when something is evident from logical deduction, why bother calling it into question?
My own two feet! And yours!
Oh come on, SY! Floor conduction is a pretty well known issue, not some ooga booga that no one has ever studied before!
First a simple empirical test anyone can do:
place your feet firmly on the ground, then play a recording with big bass percussive whacks, spaced apart so you can notice individual whacks.... and put just a little attention to which one you notice first.
Most people, assuming they have enough sensation in their feet, will readily FEEL the conducted wave first.
If you're feeling it, you are also perceiving it, which means you are pre-alerted to the bass transient right? With speakers at 3m or so, this'll be about 7 mS or so before the acoustic wave arrives.
Jeez, doesn't the above seem self-evident?
But maybe the above needs a DBT test to see if the subjects can clearly notice whether their feet are on the ground or not.
OK, so now you want measured data? DIY !! It's easy!
Put accelerometers at the floor under the speaker, and another under your feet at the listening location at 3m or so and measure it. Use a digital scope and then look at the difference in vertical amplitude between triggering signal and what arrives at your feet. Time gate it for various times after trigger, maybe between 5 and 40 mS, and look at them waves.
For transverse waves you can mount the accelerator on a block and secure the block to the floor so the accelerometer is at 90 degrees to the floor. Turn the block 90 degrees to measure lateral transverse waves.
Look, I'm not interested in providing proof for things that are evident from logical deduction. Especially with the rigor demanded by some who presume to be authorities because they have conducted much research in other fields.
However...
about 30 years ago I did some tests on an old suspended floor... using single shot filtered pulses with a digital scope, averaging results to increase s/n ratio, and quite was shocked to see just how little attenuation there was, and even more when I changed the time gating to see how additive interference from reflections, coupled with the floor's resonances were 20 to 30 dB higher in amplitude at the feet than at the origin (at some frequencies).
As for what actually arrives at the inner ear and its audibility? Since you like doing research, I refer you to the medical studies that exist on bone conduction.
Here is a study about feet to ear hearing, where the research is done on elephants, with some parallels drawn to the human auditory system:
Research Labs
When I get the time, I might try to do a comparative study with accelerometers on the feet and the bones in front of the ears just to be able to see how much of is getting through, unless I can find a study which has already been done. But I don't think it's very useful to debate whether it is perceptible or not, that part is pretty well established. and rigorously so.
Where it comes to being able to detect vibration through the floor, it's already QED, but I haven't generated or seen any studies which define by how much.
Look, SY, your bias in favor of doing exhaustive research with scientific rigor is fine, and very much appropriate for publication in scientific journals. But this is not such a publication, and when something is evident from logical deduction, why bother calling it into question?
Floor vibes
But what I CAN attest to is that strong bass pulses were readily "foot conduction discernible" on EVERY concrete slab I've ever listened on with conventional speakers. Haven't you noticed this also?
Keep in mind, the assumptions about whether or how conduction reaches the ear may be insufficient to define this...
There are many studies that have been conducted on clinically deaf subjects, precisely to help identify localization capacities and help them navigate better.
That's an assumption which while it may appear logical, may not actually be true. Perhaps we have some architectural engineers who could comment better on this issue, the brief study I did was on a suspended wooden floor, which most definitely was NOT constrained to near zero.
Although there are many studies concerning this in architectural journals, especially where it concerns earthquakes and LF vibrations, I myself have not tried to quantify it, nor the differences between transverse and longitudinal components.
But what I CAN attest to is that strong bass pulses were readily "foot conduction discernible" on EVERY concrete slab I've ever listened on with conventional speakers. Haven't you noticed this also?
Keep in mind, the assumptions about whether or how conduction reaches the ear may be insufficient to define this...
There are many studies that have been conducted on clinically deaf subjects, precisely to help identify localization capacities and help them navigate better.
My feet tell me that my floor isn't vibrating. Logical or not, despite your claim that concrete's vibration transmission is significant. Maybe the bass extension of my speakers is insufficient...
Bass transmission through floppy floors (anyone with a turntable can tell you about that) is a far cry from the HF fingertip stuff you claimed "corroborated" your "research."
Bass transmission through floppy floors (anyone with a turntable can tell you about that) is a far cry from the HF fingertip stuff you claimed "corroborated" your "research."
One need only visit Gary Pimm's house to know that the floor bass doesn't always get there before the air borne bass. It's quite fun.
One of the reasons I have and like concrete floors in my listening room..
(Well it is a basement listening room, and my second - a deliberate choice.)
Wow
In what way are you threatened by my suggestion that maybe, just maybe it's useful to try measure what's happening to the test subjects too?
Come on SY, you're a scientist, yet the tone, and the verbiage and the implications from your questions resemble something from the inquisition. Are we all here to kneel before the Church of DBT ?
If you want to disbelieve the validity of GSR and EEG testing, go ahead and do so. But first study the issues, and talk to those who know them well... neuro-physiologists. I based my work on the inputs of a team of these guys. I don't feel I need to answer to you !
If you want to call my credibility into account, go ahead. I don't have much to lose, and I'm too old to care.
Only, I'm not going to play this silly game of trying to justify my work to people who claim immense professional credibility and then impugn others work because they won't provide the "evidence" in the format required by the Church of DBT.
In this country we are presumed innocent until proven guilty. My refusal to "hand over" all my data is not an admission of guilt, it's motivated by four factors:
1) It takes too much time.
2) There's no payoff in doing so.
3) I would have to reveal some trade secrets before I'm ready to do so.
4) I don't quite trust your motives.
Impugn all you will, all you can prove is that I haven't given you the data. This means ZER-o when it comes to actually determining if my work is valid.
Besides, the real proof is in the pudding. Despite our obvious disagreements, you are cordially invited to come hear what I have built.
If you do, my guess is your objections will largely fall away, even if you do go away thinking these speakers sound good only because they measure very, very well by conventional FR, THD. IMD and other traditional metrics.
You want me to play by your rules? Try playing fair.
'Nuff said.
Why the specious attacks?
In what way are you threatened by my suggestion that maybe, just maybe it's useful to try measure what's happening to the test subjects too?
Come on SY, you're a scientist, yet the tone, and the verbiage and the implications from your questions resemble something from the inquisition. Are we all here to kneel before the Church of DBT ?
If you want to disbelieve the validity of GSR and EEG testing, go ahead and do so. But first study the issues, and talk to those who know them well... neuro-physiologists. I based my work on the inputs of a team of these guys. I don't feel I need to answer to you !
If you want to call my credibility into account, go ahead. I don't have much to lose, and I'm too old to care.
Only, I'm not going to play this silly game of trying to justify my work to people who claim immense professional credibility and then impugn others work because they won't provide the "evidence" in the format required by the Church of DBT.
In this country we are presumed innocent until proven guilty. My refusal to "hand over" all my data is not an admission of guilt, it's motivated by four factors:
1) It takes too much time.
2) There's no payoff in doing so.
3) I would have to reveal some trade secrets before I'm ready to do so.
4) I don't quite trust your motives.
Impugn all you will, all you can prove is that I haven't given you the data. This means ZER-o when it comes to actually determining if my work is valid.
Besides, the real proof is in the pudding. Despite our obvious disagreements, you are cordially invited to come hear what I have built.
If you do, my guess is your objections will largely fall away, even if you do go away thinking these speakers sound good only because they measure very, very well by conventional FR, THD. IMD and other traditional metrics.
You want me to play by your rules? Try playing fair.
'Nuff said.
Let's stay away from personal remarks and reflections, shall we?
Quite the opposite. I think controlled measurements of test subjects and controlled listening data are of the utmost importance. This is a technical forum, and progress and learning depend on data.
Like I said before, I'd be highly interested in hearing your speakers. I like good quality omnis. Fairfield is a bit of a haul from here, unfortunately.
floored
I made no claim that all floors will show big amplitudes of transmission, only that many do, and every one I have heard so far. I have no doubt there are exceptions to this.
I have an idea: let's research the Architectural Journals and see if they have quantified any of this.
It's entirely possible your floor is really, really good this way. It's also possible you have your speakers mounted on stands that decouple them from the floor... there are people who make a lot of money making stands for this precise reason.
I made no claim that all floors will show big amplitudes of transmission, only that many do, and every one I have heard so far. I have no doubt there are exceptions to this.
I have an idea: let's research the Architectural Journals and see if they have quantified any of this.
So we have Pano feeling the bass through the (concrete?) floor, Jack telling us that he has done tests which have shown this effect & Sigh! telling us he can't & looking for empirical measurements Perhaps there's something wrong with his feet or sensory system? B12 check in order!
Perhaps there's something wrong with his feet or sensory system? B12 check in order!It's progress also is dependent on ideas that are allowed to be expressed without the need for accompanying measurements. The stifling of such ideas is what I believe Jack is talking about in the "church of DBT" reference! It prevents the free exchange of ideas. These ideas can then be tested & evidence produced if it is considered to be warranted by anybody who is interested in doing so or not as the case may be. Ideas that have no value have a way of disappearing & causing no disturbance in the fabric of reality!
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My Onkens actually sit on plywood frames and the direct contact area to the slab for both boxes combined is probably less than 3/4 sq ft. (contact force over that area is probably more than 3psi) I'm relatively sure that I feel little through my 101yr old slab most of the time, but now I find myself questioning that.
Thanks a lot guys! C'mon up...
On my list of things to do for kicks and grins (and yes, for marketing) is to measure and record the suspended hardwood floor here at my place, and then show the graphical comparison between a force-cancel system and a non-canceling system. With both calibrated to the same FR and SPL, and then subtract the one from the other.
I've been trying to figure out how to "convert" data from an accelerometer into useful measurement of SPL, but it's difficult to calibrate...
but maybe the best option is simply measure the floor directly with the mic about 1 cm away, average it many, many times to increase SPL and knock out extraneous LF data, and then time-gate the impulse response to exclude the acoustic wave.
It's funny, I didn't set out to build an omni, I was shooting for time-correct behavior and realized that to do it right, it has to be time correct pretty much everywhere on and off-axis. And so an omni was born. And then I wanted it to be force-canceling, and the big system was born, also omni.
Next up will be an attempt to build a uniformly restricted directionality OB system which is also time-correct through the entire beam-width.
Tell you what though, the DEQX HDP-3 I'm using for this work really allows some great choices, with very little compromise and tremendous flexibility. It's pretty easy to get FR within +/- 0.2 dB with this...hmm.. maybe I should publish a FR graph? It's data, and I'll tell you what, it sure loooks pretty...
Data... what's that?
On my list of things to do for kicks and grins (and yes, for marketing) is to measure and record the suspended hardwood floor here at my place, and then show the graphical comparison between a force-cancel system and a non-canceling system. With both calibrated to the same FR and SPL, and then subtract the one from the other.
I've been trying to figure out how to "convert" data from an accelerometer into useful measurement of SPL, but it's difficult to calibrate...
but maybe the best option is simply measure the floor directly with the mic about 1 cm away, average it many, many times to increase SPL and knock out extraneous LF data, and then time-gate the impulse response to exclude the acoustic wave.
It'd be great if you get the chance.
It's funny, I didn't set out to build an omni, I was shooting for time-correct behavior and realized that to do it right, it has to be time correct pretty much everywhere on and off-axis. And so an omni was born. And then I wanted it to be force-canceling, and the big system was born, also omni.
Next up will be an attempt to build a uniformly restricted directionality OB system which is also time-correct through the entire beam-width.
Tell you what though, the DEQX HDP-3 I'm using for this work really allows some great choices, with very little compromise and tremendous flexibility. It's pretty easy to get FR within +/- 0.2 dB with this...hmm.. maybe I should publish a FR graph? It's data, and I'll tell you what, it sure loooks pretty...
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Got concrete?
BTW, I should mention that in general, I MUCH prefer the concrete slab on ground option... methinks just about any non-force canceling speaker will sound better on such...
of course, there may be exceptions, and someone's wood floor will perfectly complement their speakers and room modes... but that ain't the general case.... I think
TBH, I'd love to have a better floor at my place, it would show my smaller speakers in a better light. The big ones, being force-canceling, are much less bothered by this... in a room w . concrete floors the audible differences between them are much smaller.
AND... it could well be that SY has a really great floor, and really doesn't get much in the way of readily perceptible vibrations from it.
BTW, I should mention that in general, I MUCH prefer the concrete slab on ground option... methinks just about any non-force canceling speaker will sound better on such...
of course, there may be exceptions, and someone's wood floor will perfectly complement their speakers and room modes... but that ain't the general case.... I think
TBH, I'd love to have a better floor at my place, it would show my smaller speakers in a better light. The big ones, being force-canceling, are much less bothered by this... in a room w . concrete floors the audible differences between them are much smaller.
AND... it could well be that SY has a really great floor, and really doesn't get much in the way of readily perceptible vibrations from it.
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I have a terrible fear...nay, more like a conviction.... that the above is what will happen to both me AND my ideas......given enough time, it's a certainty
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My 2 cents for "evident logical deductions" and "bass through the floor" :
I had H frames with 15" EQed to be flat to 25Hz. In the lowest tunes, they were emitting a strange noise, obviously aerodynamic noises from the back of the basket (was not digital distorsion). As a proof, this disappeared with the frames fitted back to back.
Years after, I tried thick soft rubber pads under each separated H frame : no more "aerodynamic noise"...ahhhh.
so :
>>>brilliant evident deductions are sometimes of no value
>>>woofers have relationships with the floor, hanging from a structure cures that
I had H frames with 15" EQed to be flat to 25Hz. In the lowest tunes, they were emitting a strange noise, obviously aerodynamic noises from the back of the basket (was not digital distorsion). As a proof, this disappeared with the frames fitted back to back.
Years after, I tried thick soft rubber pads under each separated H frame : no more "aerodynamic noise"...ahhhh.
so :
>>>brilliant evident deductions are sometimes of no value
>>>woofers have relationships with the floor, hanging from a structure cures that
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