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Testing audiophile claims and myths

Discussion in 'Sound Science' started by prog rock man, May 3, 2010.
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  1. Steve999
    That all is pretty darn speculative, IMHO. I keep a decibel meter by my listening position at home. For me 70 dB average for music in the home at the listening position for any reasonable period of time is definitely a little uncomfortable. Over 90 dB at home at the listening position for me is ridiculous, even for peaks. That’s either a weighted or c weighted. And we don’t know how the Pioneer handled peaks. The test was over 40 years ago. We’ve picked it apart to death. It’s not the be all and end all but it had a lot going for it and it is one piece of important information. And again, who cares? Time to move on to other stuff, maybe less than 40 years old, IMHO. And to change the focus of the thread to testing and away from wild speculation. :)
    Last edited: Jun 13, 2019
  2. taffy2207
    This thread reminds of this lately :grin: :-

    bigshot and Steve999 like this.
  3. GearMe
    Kinda my point...crappy test with incomplete write-up and possibly flawed assumptions.

    FWIW...most folks I know that have good systems tend to play them at realistic levels...not human conversation/dial tone levels.

    Merely trying to emphasize it's not as black and white as this thread often 'paints' it to be.
  4. KeithEmo
    Cables and electronics... I very much doubt it.

    However, the flexible mechanical suspension of speakers and many headphone drivers does change over the first few, or few dozen, hours of use.
    This will result in easily measured differences in performance (the free-air resonant frequency will become lower as the suspension gets softer - resulting in a lower in-box resonance).
    However, usually, the specified performance parameters of the parts involved, and of the entire unit, are measured after this so-called burn-in period.
    (So it's more likely to fail to meet spec before burn-in than the other way around.)

    In sealed enclosures, and those with open backs, the difference is usually minor.
    However, with tuned systems, like ported speakers, where it may cause the tuning to work properly or not, it can make an audible difference.

    analogsurviver likes this.
  5. analogsurviver
    Any mechanical transducer after any longer period of non-use has to "warm up" - say at least half an hour of normal operation.

    There are quite a few known cases there were problems in ported enclosure speaker production - because, at some point, driver manufacturer has made some changes to the mechanical parameters of the drivers - WITHOUT telling the speaker manufacturer. I has only been brought up AFTER the numerous reports of customers auditioning defective speakers at dealers have reached the company - and the complaints by the prospective purchasers turned out to be true.

    One can count burn in as an additional step in Quality Control - which, unfortunately, costs both time and money. In a highly competitive environment, it is all too easy to be left out.
  6. KeithEmo
    If you have EVER found a PERFECT null between anything - including two supposedly identical channels on the same amplifier - I would love to hear where it was.
    (Or are you suggesting that you get to decide what's "a good enough null" that we can ignore what's left?)

    Incidentally, you said that "we tested thousands of teenagers over several years"... and then quoted the "mean highest frequency response".
    I seem to be having trouble finding a precise definition of that term.
    A "statistical mean" is a specific form of average... while the meaning of "highest" seems to be obvious.
    Perhaps, if we could see the actual scores, we could pick out what comprises simply "the single best score" and see what it is.

    I agree entirely with your comment about professional engineers....
    Any test to measure a limit of human hearing "ability"....
    - Should include both professional engineers and professional musicians (because they may reasonably be expected to have the "most well trained ears"....)
    - Should include young children (because we know they usually have the best measured "hearing acuity".....)
    - Should also include subjects from a wide variety of racial and genetic (because we need to consider that hearing acuity may be linked to specific genes.....)
    (It isn't practical to test every human on Earth... but you should at least include any and all groups who it can be reasonably suggested MIGHT be significant outliers.)

    And, yes, all joking aside, you SHOULD allow the widest possible latitude when deciding what subjects to include - because human characteristics are well known to "clump".
    And, yes, that does also include applying common sense.
    I doubt that a human baby would be likely to run faster than a professional adult runner.
    However, it is ingenuous to suggest that has anything to do with whether one may have better hearing acuity than you or I (or anyone else).
    For example, it would be a mistake to attempt to determine "how long humans live" without including people from the one town in Russia where many seem to live exceptionally long.

    Incidentally, for the person who posted about "how ridiculous it would be to believe that a human could run a mile in two minutes"....
    I happened to look at the actual statistics (there's a nice graph on Wikipedia).
    The "best recorded one mile time" has improved a full 20% in the past 180 years.
    I'm not so sure that considering that it might improve 50% in the new few hundred, or the next few thousand, would be foolish at all.
    (Or that it would be beyond possibility that an outlier alive today might conceivably do so. Quite unlikely - yes; impossible - maybe not.)

    Also incidentally, the current official one-mile record is held by a fellow named Hicham El Guerrouj.
    He beat the "four-minute mile" by a solid quarter of a minute.
  7. Steve999
    The equivalent of a fortissimo (that literally means “very loud”) singer three feet from my face or practicing at the piano will do fine for me for long-term listening in the home. ~70 dB average, according to your chart, depending on how you measure it.

    And hey, that’s something I’ve actually researched, tested and measured! Cool!
    Last edited: Jun 13, 2019
  8. Phronesis
    For me, when the discussion goes in circles, it becomes uninteresting. It would be possible for the discussions to enter new territory if they were truly scientific, but the predominant agenda of Sound Science is to debunk audiophile myths rather than do science. That's not an unreasonable agenda, but it mostly amounts to preaching to the choir. Discussions in head-fi outside of Sound Science are no longer particularly interesting for me either, because they usually involve people expressing subjective preferences and propagating audiophile myths (and trying to debunk them can get you banned). Hence no change in avatar in quite a while, but just for you, I've now changed it.
    Steve999 likes this.
  9. bigshot
    I think you have a problem with me because you are more interested in self validation than finding out the truth. There's nothing I can do to help that. I don't think you are capable of interacting normally with me because you can't talk *with*, only *at*. I don't think that is deliberate.
    Last edited: Jun 13, 2019
  10. bigshot
    It's easy to misjudge numbers on a page. I always recommend that people who are interested actually make an effort to experience what those numbers mean in real world sound to be able to put the numbers in perspective. For relative volume levels, I'd suggest picking up an SPL meter, and turning up your home stereo to a normal loud listening level and measuring it. I bet if you measure your own speaker system, you'll find that you aren't going much over 70dB.

    The loudness where the sound reaches your ear is what counts, not the volume emitting from a sound source when you are standing right in front of it. For instance, a symphony orchestra has instruments that can put out volumes of as much as 110dB, but that doesn't mean that you hear it that loud from the audience. Out in the seats, it's more like 60dB.

    For point of reference, 85dB is the OSHA limit for protection against hearing damage. That is well into the "flinch zone". And well recorded music generally has a dynamic range of under 50dB or so, so 80dB is about the point where you can hear all the way down to the theoretical noise floor over a room tone.

    Headphones are a little different. Since there is no space between the headphone and your ear, it's easy to misjudge volume and end up listening too loud. A lot of people damage their hearing that way.
    Last edited: Jun 13, 2019
    Steve999 likes this.
  11. bigshot
    You finally did a blind, A/B switched, line level matched listening test? That's great! I was waiting for that a very long time. What did you compare? Tell me about your test. I honestly want to know how you went about your first controlled test. I don't just want to pick it apart. If you applied the three main controls and compared apples to apples, that is very interesting to me.

    Actually, the purpose here is to apply scientific principles to improving the sound of home audio systems. It's the practical application of science to achieve a specific goal- perfect sound for the purposes of listening to recorded music in the home. We spend so much time on myths because people come in here and try to convince us that up is actually down and right is actually left. That does waste an awful lot of time.
    Last edited: Jun 13, 2019
  12. analogsurviver
    Well, there is no such thing as relative volume levels. It is what it is - at any given moment.

    You seem to forget I deal also with binaural. And that records - and reproduces - PRECISELY at ear levels - both as position and SPL. When using artificial head for recording, monitoring with IEMs under mufflers , I often double check for volume of monitoring - and, despite always seating in some far corner of the venue, where there is less sound than in the centre of the venue behind the conductor, the live sound is almost always a few dB louder than what I am listening to directly from the mics in headphones. I did pay attention to that years ago; monitoring in same acoustic space as live music requires almost perfect sound isolation - and if the opposite is what is used, you end up cranking the sound of headphones WAY too high - just to arrive at point the sound of the monitor overpowers the sound of live music and you get at least vague idea what is getting recorded. Listening to such high volume not only is dangerous, it also totally skews all relationships.
    So, it has been one of my first things to take proper care of.

    If I record using my own head wearing mics in the audience, then it is direct 1:1 relationship - I do not go on stage and crawl into the piano ... - or whatever that silly.

    And, no, Mahler 2 live does not have only 50 dB dynamic range, nor it peaks at only 80 dB SPL - both at the precise location of a person attending the concert.
    Today it is possible to record and reproduce it at true to life levels - at least when using binaural. And proper "headphones" for binaural DO have space between headphone and your ear.
  13. dprimary

    This is news to every audio engineer in the world. Ninety-nine percent of levels are relative. Absolute levels are rarely known. Unless you have measured the dB-SPL unweighted and calibrate to it everything is relative. Until record companies start putting a calibration tone in an album, with instructions on calibration your system to that level they are just guessing.
    Steve999 likes this.
  14. bigshot
    How can I forget? You constantly bring that and phono cartridges up even when it’s irrelevant to the conversation and no one else is particularly interested. Your conversations don’t extend further than your own head. I know that isn’t your fault though.
  15. analogsurviver
    OK, in that context, it is so. For now.

    But, there will come time calibrating the original sound during the recording and making sure that replay gain in player software and volume setting for the headphones/speakers used would be, if not exactly the same, say no more than 2 dB off the target value. Such a requirement would also have to include calibrating/equalizing headphone/loudspeaker . Music is supposed to be played at certain loudness - and reproduction should follow that as closely as possible. Although Fletcher-Munson curves might not be 100% correct, the sound timbre DOES change with volume - thus real music levels and those of reproduction should ideally match. Maybe Fletcher-Munson curves should be re-examined, improved if required and incorporated into player software, where listener would be required to input the desired peak SPL level - and DSP would automatically provide the correct required EQ curve.

    When we arrive at about this kind of universally accepted agreement ( like smartphone world finally agreed on charger connections ) - then we might start talking about "no audible difference". Provided, of course, that electronics and transducers can provide frequency response and dynamic range required or even specified against some kind of minimum requirement standard.

    I concur that remote controlled volume for listening via speakers is more important than the last n-th degree of the sophistication of the amplifier. The volume setting that does work in any given room at home can be off by low enough amount that a listener would not bother making the trip to volume control and back - whereas a remote control can be used for fine volume adjustment.even by a single listener. Having to make fine volume changes by ear in different location than listening area can be hard; particularly with dipole speakers. If your volume knob is anywhere close to the dipole plane, there would be close to zero output at your volume setting position. It is far less hard to do with point source speakers - but still far harder than from listening spot with a remote.

    I have started putting calibrating tones in my recordings from vinyl - referenced at 1 kHz @ -18 dBFS. Both for any comparison purposes among various cartridges/arms/tables, as well as a proof that the cartridge used has actually been properly installed and adjusted. Although this adjustment of recording level can be royal PITA ( cartridge outputs vary from 0.04 to more than 5 mV at reference 1 kHz/5cm/sec ) and is sometime not only impractical but altogeher impossible ( the range of gain control required is outside most equipment) , I do try to follow it as closely - within reason. I would not put yet another line stage between the phono preamp and recorder input if the output of the cartridge "lacks" less than 3 dB from target value. There is always calibration tone of 1 kHz available for comparision volume matching.

    Now, it would be fine if a relatively inexpensive reference "noisemaker" for actual musical recording could be made available to everyone. That could be the beginning of putting calibration tones in the recordings of commercially available music.
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