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ADEL Technology - Discussion Thread - Update: March 27, 2016: Please Read 2nd Post of the Thread

Discussion in 'Sound Science' started by eaglewings, Mar 7, 2016.
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  1. krismusic Contributor
    I mean. Is ADEL addressing a problem that actually exists?
  2. Ruben123

    That is the thing were all wondering. Does it exist, is it a problem, and if it is a problem, is it significant to solve the pressure "thing" while still having the volume/loudness.
  3. Ruben123

    I've read it, thanks! Unfortunately a lot of claims are made, and no many proves are given. A lot of speculation which the authors find probably common sense.

    1 thing that for sure is very wrong: the m. Stapediusreflex causes a decrease of 15dB in the lower frequency range and certainly not 50dB!!! So conclusions based on that claim are wrong too. Will come back at the rest this afternoon when I finally have some more time.
  4. WCDchee
    I would not mind taking part if the timing is right.

    Perhaps I could list some issues I have with the concept of the ADEL module.

    With regards to hearing loss, as some of us discussed previously, what actually matters is the amplitude of vibrations reaching our inner ears. If you take a look at the ADEL claims, all that is ever mentioned is that lower volumes are required because the stapedius reflex isn't triggered as early. However, that really doesn't answer any questions as the triggering of the stapedius reflex merely means that the amplitude of the vibrations reaching the inner ear is reduced. It would be lovely to hear Stephen chime in on this.

    Now with regards to this thing called pneumatic pressure, I fail to see how this damages the ear. If anything with the build up of pressure in the ear, the eardrum compliance falls, resulting in a decreased amplitude of sound waves reaching the inner ear, and this actually protects the ear if you get my drift.

    The third issue is regarding the concept of listening fatigue. What exactly is that? Because to be honest, I have never experienced it. And neither have a lot of my friends. Perhaps I'm lucky, I don't know, but it has to be something quantifiable. And scientifically, until listening fatigue can be properly quantified, it should not be something upon which an argument is based.

    And now, given my understanding of the ear, as well as hearing loss from the ENT perspective (I understand audiology has a lot of research in this too, I'm in no way attempting to put it down, it would be lovely if I could better understand it :) ) I cannot see how pneumatic pressures or the triggering of the stapedius reflex damages the inner ear. If anything, they protect your hearing.

    Similarly, there's a big jump from the concept of listening fatigue to hearing loss. Firstly, listening fatigue must be quantified and explained adequately, only then can we examine the causes for it, for if listening fatigue cannot even be fully and properly quantified and explained, there is no point examining the causes of listening fatigue, because there would just be way too many confounders. After deciding the scientifically quantifiable and objective definition of listening fatigue, we must then examine the causes, and how this listening fatigue links to hearing loss, if there is a link at all.

    I hope what I've said makes sense :) I've previously chatted with a few guys and Tyll on PM regarding this, and I've got a pretty Long write up to explain the mechanics from my understanding, if you guys are interested, I will be happy to post it here :)
  5. ken6217

    Well if they are saying that this will save our hearing, then they are wrong.

    I do not need to know anything more than common knowledge and common sense that playing something loud into your ear can cause hearing damage at some point.

    As I've mentioned before, being exposed to lawn equipment, heavy machinery, concert venues, etc, over time can lead to hearing damage, and there is NO PNUEMATIC PRESSURE IN YOUR EAR.

    The only argument that they can try to make is that pressure plus volume can cause hearing loss, but with the ADEL module the pressure is relieved and this makes us safer than IEM's with no module. The save your hearing comment is marketing and deceptive I believe.

    There is a reason why OSHA publishes safety decibel levels in the workplace. I cut and pasted from their website:

    "The employer shall administer a continuing, effective hearing conservation program, as described in paragraphs (c) through (o) of this section, whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent. For purposes of the hearing conservation program, employee noise exposures shall be computed in accordance with appendix A and Table G-16a, and without regard to any attenuation provided by the use of personal protective equipment."

    Since they are not talking about IEM's, then it is obviously known about loud volumes and hearing damage from external noises. Then we can all conclude loud noise does cause this. We also know that playing music in ones ear can produce loud volumes. So therefore IEM's can cause hearing damage from volume alone.
  6. Brooko Contributor
    Jeepers - a lot of absolutes in here - and I'm surprised that there is not more questions on how the science is supposed to work instead of all the "no it can't".  Isn't the idea of this to actually see if there is new science/thinking/knowledge behind it?
    I'm no expert - but reading what is available so far, see if this makes sense.
    What we think we know:
    1. The louder sound, the more likely we are to induce temporary, and more likely permanent hearing damage
    2. The ear has a safety mechanism (the acoustic reflex) which when triggered by loud sounds, lowers the amount that can get through to the inner ear.  This refelx has limits.
    3. When we're talking about loud sounds/noise/music - we're talking about the sound pressure level
    What Stephen and his team are proposing (and he's got funding for research, so some scientific types seem to think he's onto something)
    1. When closing the ear with an IEM, you not only get normal sound pressure, but this is multiplied (small space, nowhere to escape) so you also get magnified pneumatic pressure.  Whatever it is, it is increased pressure.
    2. This increased pressure causes the acoustic reflect to kick in early, possibly even at lower actual sound levels - which means to our senses, music is a lot quieter (because of the acoustic reflect defense mechanism)
    Now here is the connection a lot of you may be missing
    1. The natural reaction to thinking the music is too quiet is to turn it up
    2. This continues to tweak the acoustic reflect until it reaches its limits
    3. All the while pneumatic pressure continues to build, as does the true loudness of what we're putting into our ears - and hearing damage/loss is a likely result
    4. Eventually the acoustic reflex is overwhelmed, we get to the volume we prefer, and we're in for some long term trouble.
    The ADEL proposal (I think) goes like this.
    1. The ADEL module releases some of the pneumatic pressure so that the acoustic reflex is not triggered too early
    2. Because of this, at much lower (safer volumes) we are more likely to be satisifed with the volume we have, and not turn it up to an extent where the sound waves will naturally trigger the reflex.
    3. If we're not in a continual loop of turning the volume up and triggering the reflex, then the sound waves won't get to the point where damage occurs.
    Ergo - yes - it has the ability to help prevent hearing loss if used correctly.  Or maybe more correctly - IEMs without ADEL have the ability to trigger the acoustic reflex earlier, starting the dangerous cycle of increased volume.
    Does this start to make sense?
    Of course the caveat in all of this (as some of you have already pointed out) is that for it to work, we need to be prepared to listen at safe volumes.  Unfortunately ADEL can't save the people who listen loud anyway (and there are a lot who do).
    In my particular case with the U6 I have - some of the things I've noticed:
    • I am actually listening quieter (I'm a quiet listener anyway - mid 60 - mid 70 dB most of the time. With a good seal with the U6 I tend to be at the bottom end of that scale.
    • More often than not, I tend to turn the U6 down over time.  A lot of other IEMs I tend to turn up.  I wonder how many of you (with other IEMs) do the same? (now relate that to the points on acoustic reflex and sealed canal)
    • I have permanent tinnitus.  One of the big things that has happened with the U6 (and my lower listening) is that it doesn't flare as much as with other IEMs.  A couple of hours with other IEM's and when I stop the ringing will be more apparent.  With the U6 it is a lot quieter and I don't notice it.  If we're talking listening fatigue - this might be a sign
    Now - before anyone jumps in boots first with the critiques of my not very learned understanding:
    1. I don't work for Asius
    2. I have no skin in the game - I paid for the U6 (KS price) - what I've written above, and especially the bits about the lower listening over the last few months and the tinnitus fatigue are true.  I have no reason to make this up.
    3. I'm keeping an open mind on everything until I learn a lot more - but what I'm experiencing at the moment tells me that there might just be something in this ......
    Canyon Runner likes this.
  7. Ruben123
    Short-cant wait for this evening to have time.

    First: I indeed always lower the volume over time, be it with speakers or headphones.

    Second (and last): if you're listening at 90dB and the m stapediusreflex works at max damping, your inner ear will "hear" 75dB. If you're listening with the adel at 75dB and IF it works and the m stapediusreflex is not used, it stays 75dB for the inner ear.

    So what does it add? This evening I will take many of the statements and put it in my post.
  8. WCDchee

    Yes this is precisely my point :)
  9. Brooko Contributor
    But we already know that 75dB measured isn't going to cause as much damage as 90dB measured. So how do you expliain that - if the acoustic reflex has been triggered and they both are same in inner ear?
  10. Brooko Contributor
    Thought some more about this - 
    • Speakers and headphones are not what I asked about.  I specifically asked about IEMs as the others will not have the effect of building pneumatic pressure.
    • So if 90 dB and 75 dB put same volume at max damping to my inner ear - why is the 90 dB un bearably too loud for me - while the 75dB would be OK?
      Actually I should qualify this as well - with IEMs I listen even lower - will measure when I'm home.
    • Could you please cite references for the bits you quoted on how the inner ear dampening works (the 15 dB difference) 
  11. WCDchee

    Let me try to explain it from my understanding :)

    Hearing loss is brought about by trauma to the hair cells in the cochlear. This is caused by excessive sound pressure levels in the cochlear.

    The cochlear is a snail shell shaped bony organ which is filled with fluid. When sound reaches the eardrum, it is conducted via the ossicles to an opening called the oval window.

    Now imagine the cochlear as a drinking straw coiled up into a helical shaped object. Now put two diaphragms, one on each end of the straw, and fill the straw with fluid. When you press one of the diaphragms, the other end will bulge out. This allows the fluid in the straw to oscillate, and is pretty Much how the cochlear works. One of these diaphragms is the oval window, the other the round window.

    Now back to the above. Vibrations are transmitted to the oval window, causing the fluid in the cochlear to oscillate. When the amplitude of these oscillations becomes too large, there will be trauma to the hair cells.

    Now, if we look at what happens in the stapedius reflex, what actually happens is that a muscle contracts to make the eardrum more taut. As such, the same sound pressure level hitting the eardrum results in a now smaller amplitude of vibrations in the eardrum.

    As such, answering your question above, when comparison two situations

    A) the stapedius reflex is activated
    B) the reflex is NOT activated

    90db of sound pressure would result in a smaller amplitude of oscillation of the eardrum in A Than in B.

    Now the conduction of vibrations down the ossicular chain is just a lever mechanism, and thus, having smaller vibrations at the eardrum results in smaller vibrations sent down the ossicular chain, and thus smaller vibrations in the cochlear itself.

    This is the reason that the sound seems softer to us, because it is literally, physically damped before reaching our inner ear.

    This damping mechanism is what's described in my textbooks :)

    Therefore, assuming now, that 90db is being played, and the stapedius reflex damps 15db (this is purely arbitrary in this case), then in scenario A, there would actually be less inner ear damage than in scenario B.

    I would love to share a little more of my understanding of the hearing physiology if you guys would like, but my computer is down at the moment, so typing on my phone is quite the pain. If you have any more questions regarding this, I would gladly find a computer to type more out :)

    Hope this answers some of what you're asking paul!
    sonitus mirus, Brooko and Ruben123 like this.
  12. WCDchee
    If you would like to better understand this damping mechanism, you could check out something called the tympanogram, where eardrum compliance is measured at different pressure levels of the outer ear. This basically shows that as the eardrum becomes more taut, compliance decreases, and as such, a larger Force is needed for the same amplitude of vibrations. This explains why the damping occurs. As for why this means that we actually hear less, it's because the ossicular conduction chain is merely a lever, it merely takes the vibration at the eardrum and multiplies it by a fixed magnitude (20-30 times if I remember right). Thus, a smaller amplitude of vibrations at the eardrum would necessarily mean that a smaller amplitude of vibrations reach the inner ear.

    Also, Brooko, another thing I would like to point out. You did mention that the sound pressure in a small sealed area would be magnified. This is not too accurate as this would literally mean creating energy. Also, you used the terms sound pressure level, pneumatic pressure, and pressure, rather interchangeably. I must note however, that these are completely different things, and shouldn't be confused to be interchangeable :) for example, building up of pressures will not cause SPL to rise. Pneumatic pressures also do not cause SPL to rise. Hope this clears things up :)

    I think the main beef I have with a lot of the marketing claims, is that a lot of these extremely technical and specific terms are used very loosely and carelessly.

    Now don't get me wrong, I must re-iterate that I am in no way claiming that the ADEL module does nothing. I am absolutely convinced that it can affect the sound, positively or negatively. What I am contesting is the claim of improved hearing protection over standard IEM solutions :)
    sonitus mirus and Brooko like this.
  13. LoryWiv
    I too paid full fare for my A6 and have no dog in this fight, except that like Brooko, I find lower volume pot settings are satisfying with my A6 versus other IEM's. Clearly, the impedance, sensitivity and other factors play a role and I concede I do not have a dB meter to quantify. As for the science, what I have observed after 30 years in healthcare is:
    1. Hypothesis are developed from 1st principles, but require well-controlled clinical trials to prove or disprove.
    -At this point I accept that the underlying 1st principles are reasonably compelling, and think Brooko's post above formulates the premises and assumptions well, but they are only that until subjected to clinical trials.
    2. Cause and effect conclusions reduced to a single variable causing an effect are very tenuous, requiring a univariate analysis with all other factors well-controlled for.
    -As noted, hearing loss is quite likely multi-factorial, with exposure to excess dB a major factor and including both IEM related and not (most of us do go out in the world, where jet engines, rock concerts and screaming children lurk around many corners.)
    -Thus, a well-controlled experiment with univariate analysis may be very difficult to design and conduct regarding the effect of ADEL-equipped IEM's on hearing loss versus non-ADEL equipped IEM's
    -In the absence of a well-controlled, randomized prospective clinical trial, other methodologies (EG - comparisons of ADEL IEM users with with historical control cohorts, matching / controlling as well as possible for confounding variables) may be considered but represent less rigorous quality of evidence, just a bit better than anecdotal or consensus of expert opinion in the "Evidence-Based Medicine" lexicon.
    3. Pending the next level of evidence, people make the most informed choices they can about managing their health and risk mitigation. Reasonable people can differ.
    For myself, I have chosen an ADEL-equipped IEM as I greatly enjoy the sound signature and do not feel I am compromising on enjoyment. If pneumatic pressure is more rigorously determined to mitigate hearing loss, I am ahead of the game. If not, I've still got a terrific IEM that brings me joy.
    I'd offer 2 last comments based on meeting Mr. Ambrose (and Vitaly) recently at CanJam SoCal.
    1. His passion for examining new technologies that sound great and may diminish hearing loss risk was palpable. I've seen a lot of snake oil salesman in my career who knowingly and purposefully sell snake oil for profit. I got no such vibe at all from this man, and he's either an awe-inspiring actor or (far more likely) a man with great passion and integrity trying to advance a meaningful contribution to the industry beyond just market share and profit margin. Dismissing 64Audio's newer technologies as purely a marketing gimmick doesn't resonate, and is what critics all too often reduce to when they don't know how else to win the debate. Healthy skepticism is fine, but accusing 64Audio of hiring actors for their videos etc...has no place in the discourse.
    2. To my knowledge no-one at 64Audio is claiming that they have a whiz bang new technology that allows you to listen as loud as you want without risk. Obviously loud music causes hearing damage. They are looking at a piece of the equation, much as one can work to mitigate coronary risk by lowering blood pressure even though we all recognize that if we do so in a patient who has uncontrolled diabetes there remains risk. That said, better blood pressure control is still a good thing, even if it's not the only thing.
    Thanks for indulging my min-rant, and wherever one stands on this issue it has made for some (mostly) civil, respectful and lively reading.
    FUYU and Canyon Runner like this.
  14. WCDchee

    Great points you've brought up sir :)

    I hope that my Long posts haven't put anyone off or offended anyone. As I've mentioned, I'm not outrightly claiming that the ADEL is ********, if anything I believe that it can impact the way we hear things. What I would like to see more evidence on is how hearing protection comes into play.

    I've brought up some points regarding the fundamentals of the hearing physiology which I feel so not quite agree with the claims of hearing protection. If someone can provide a reconciliation for these two views, I will be happy to give it deep consideration :)
  15. LoryWiv

     Thank you for your comments, WCDchee.You fall squarely into the civil, respectful and interesting camp, good sir. [​IMG]
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