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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. dprimary
    You can't picture much at 130dBSPL your eyeballs start bouncing around at around 126dBSPL. 150 dBSPL is unpleasant on your whole body even though you have all the hearing protection you can get.
     
    Steve999 likes this.
  2. bigshot
    Too much is never enough!
     
  3. bigshot
    I have no problems just turning the volume knob down a bit. Perhaps your amp doesn't have a volume control. I know there are ones without tone controls. That is the height of stupid
     
  4. dprimary
    The scary part it modern touring systems are so clean and have so much headroom in most venues, you don't even notice how loud it is. When it harsh and distorted it easy to notice. I was at and outdoor jazz concert a few years ago near FOH thinking this sounds really good, then a few minutes later thinking this seems pretty loud, I pull out a meter shocked at the level I grab my wife to move back about 80 feet.
     
  5. TheSonicTruth
    130 SPL & up sounds like IDLING 747 territory.

    And the primary reason why I no longer attend any live concerts, and seldom even go to my church! Louder is not all!
     
  6. TheSonicTruth
    Tone/EQ not as critical as a pair of attenuators, even if they're behind a flip-up face cover.
     
  7. gregorio
    1. Firstly, if you "agree entirely" that a null test "will demonstrate even the tiniest differences" then your previous post was at best misleading: "If you hear a difference, but can't seem to find a measurement that would account for it....- maybe you're simply not measuring the right thing ... - maybe you're not measuring it accurately" - Because a null test, one of the oldest and most commonly used tests, completely covers all these assertions! Secondly, it is NOT true that if you null two of anything you will always find a little difference. For example, if you null two identical digital audio files you will find absolutely no difference. Your assertion is true only for analogue signals/components, due to the random nature of thermal noise. However ...
    1a. You appear to yet again be employing that same typical audiophile fallacy/falsehood. Maybe you personally haven't tested it and/or are not aware of the testing which has been done but it's a complete falsehood to state it doesn't exist just because you personally are ignorant of it. In actual fact the exact opposite is true, it's been tested exhaustively, over numerous decades by countless thousands of people! You say we should obviously include some common sense but then don't. For example, when I'm dialogue editing I will typically employ a null test 50 or more times a day. You think maybe that if the test reveals a small difference I just say to myself "oh well" and move on or do you think I test it to find out if it's audible and by how much? Actually, a lot of the time I do just move on, because after 20 odd years and god knows how many thousands of tests to determine if the difference is audible, I can often tell just from looking at a spectogram of the difference file. I still end up having to physically test a fair proportion of the time though, probably about a third of the time. And of course, I'm just one of many thousands of engineers who edit dialogue around the world. Furthermore and again, countless thousands of sound engineering students are taught how to conduct a null test, determine the significance of the result and demonstrate the ability to do this under examination conditions. Also of course, there is a wealth of scientific evidence to draw from. As simple and obvious example would be that if the difference file exhibits a small difference that's above 20kHz, then the science tells us it will be inaudible and this is just one of several similar examples.

    2. But of course, we need to apply some common sense! Anecdotes ARE evidence, although typically the least reliable form of evidence but also, I don't recall reading a single published scientific hearing study that didn't have at least one flaw. Audiophiles will therefore often invent a completely fallacious equivalency; anecdotes are flawed and so are scientific studies, so I logically choose to believe the Head-fi poster who actually owns a Chord Hugo over a scientist who probably doesn't even know a Chord Hugo is, let alone what it sounds like! This is a complete fallacy though because omits common sense, the common sense that all flaws are not equivalent and neither therefore is all evidence. Even within anecdotal evidence one can apply common sense and give it more or less weight. For example, I would tend to give more weight to the anecdotal evidence from Bob Katz than to the average head-fi poster because I know that Katz has considerable knowledge/experience of controlled testing while the average Head-fi poster probably isn't even volume matching. Even so, as it's anecdotal evidence I still wouldn't just accept a Katz anecdote as fact, unless it was corroborated by more reliable evidence. It's up to the individual reader whether they choose to believe the test results I have reported, which is effectively anecdotal as I can't provide the actual data to corroborate it. However, common sense dictates that there must be considerable testing, hearing ability and listening skills are absolutely fundamental to a music/sound engineer and therefore it's common sense that students hearing is tested, that they're taught listening skills and those skills are tested/examined. Therefore, it's both factually incorrect and contrary to common sense to state that "we" don't test!
    2a. There's an obvious problem with your statement. You assume that we just individually decide that a difference is inaudible and that's the end of it. Is it common sense to assume that music/sound engineers differ from other human beings in that we are all completely devoid of any curiosity? If all competently designed ADCs/DACs are transparent (have no audible differences) then no competent engineer would ever test them, however we do, regularly, because of curiosity. But how do you audibly test inaudible differences? Again, common sense, we magnify/amplify the differences. For example, it's standard procedure to loop a recording through an ADC/DAC ten times and audibly compare the result with the same 10x loopback recording through a different ADC/DAC. We've effectively magnified the artefacts of each of the ADC/DACs by 10 times and the differences are audible. Or, when testing different dither algorithms, we record the dither and then amplify it by 40dB or so and then we can audibly compare them. The obvious problem with your statement is therefore "the massive difference in the hearing acuity of a five year old", there's no evidence to even hint at the possibility that five year olds have a massive difference in hearing acuity, the evidence suggests a difference of very roughly 10% and possibly as much as 20% compared to an adult but that's no where near the 1,000% or 10,000% which we commonly have to apply in order to discern differences!

    4. Again, we need to apply some common sense! Hundreds of thousands of people, probably well in excess of a million, have had their hearing tested over the decades. Is it possible an outlier exists who has 10% more hearing acuity than anyone ever measured? Sure, somewhat unlikely but certainly possible. What about 10,000% more hearing acuity? No, that's not credible. The physiological structures in the ears aren't capable of it and anyone who had say 40dB more hearing sensitivity than me would be in constant pain, they wouldn't be able to function normally and they would have been discovered.

    1. That depends. A really loud noise that makes you jump doesn't actually need to be really loud, the human perception of loudness is relative. See #5 below.

    2. The problem with that of course is that who in their right mind would want to make their ears bleed? This appears to be a quite common view amongst Americans, that they should be free to make their ears bleed if they want or for that matter, own a gun and shoot themselves in the head. The problem is that in reality the majority of people who do make their ears bleed will either not be in their right mind, in which case you are enabling those with mental health issues to self-harm or will be children and adults who do so by accident. For this reason the EU has strict legal limits on the max level of headphone output on mobile devices, as several studies indicated young people's hearing was being damaged and incidentally, we also have strict laws on gun ownership. Also, if the level has to be raised to an "ear bleeding" level in order for some artefact to become audible, then that artefact is inaudible.

    3. Yes, but again, how loud is a cymbal crash? At 2" probably 120dB or more but at the ideal audience position, probably lower than 90dB. BTW, cannons are not a standard member of a symphony orchestra!

    4. Applying common sense, the response is that it depends. Sure, many/most amps become increasingly non-linear and noisy beyond around 80% of max amplification and I would always advise an amp powerful enough to allow at least 20% headroom. A DAC on the other hand does not require headroom.

    5. Yes, to start with, it's relative. An 80dB sound will sound very loud if it's preceded by say 40dB sound but if it's preceded by 75dB sound it won't. This fact of perception has been routinely employed in film sound for many decades, if fact audiences are commonly so expectant of a subsequent loud noise when the level gets lower, that we can use that expectancy to further surprise them.
    5a. Our hearing can adapt quite quickly, just a few seconds in the case of loudness within safe levels but up to several hours if levels have been extreme. In other words, an average level of 80dB is going to sound about the same to a librarian as a jet engine repairer as their hearing would be adapted to the level of car/traffic noise on their way home.

    You'd have noticed that I gave very different and higher figures for being close to the orchestra than for being in the audience, the close figures are based on mic'ing positions but the figures for being in the audience were not, they were based on my experience as a live sound engineer and with audiences being present. However, I'm typically basing my peak levels on a window of 0.3 secs, a peak level using a slow response would measure somewhat lower. Also, for safety sake, I'm basing my peak level of around 90dB on the most extreme examples. Although very loud for it's day and still very loud compared to say a Mozart symphony, Wagner's ring isn't as loud as it gets. Later pieces/symphonies can get louder still, Mahler being a good example but Holst, Stravinsky, R. Strauss and various others. For the vast majority of audience members, for the vast majority of performances, in the vast majority of concert venues and using a slow response to measure peaks, 80dB or so would likely be about the maximum.

    BTW, typical SPL meters are extremely poor at measuring low levels/noise floors. Typically they're only accurate for levels of around 60dBSPL and higher. Unless you have a meter specifically designed for low levels and/or a very expensive one (thousands of dollars) with particularly low self-noise, your measurement of 32dB is likely to be out by a significant amount.

    G
     
  8. Steve999
    Thanks! This is an instance where I didn’t know what I didn’t know. It makes sense though, because I don’t see any dB meters on Amazon that go below 30 dB.:)
     
    Last edited: Jun 15, 2019
  9. KeithEmo
    Anyone who worries about their hearing would be well advised to acquire a set of earplugs and bring them along when attending any live event... just in case.
    (There are specific brands and models that are deisgned to reduce the level while preserving as much fidelity as possibly - which are quite different than "safety earplugs".)

    Several years ago I attended a free public sponsored outdoor concert here in Nashville - one of our "Concert On The Green" series. However, I purchased one of the VIP tickets, which includes drinks, food, and special VIP seating. The special VIP access included the option of sitting or standing up front - just to the side of the stage - directly in front of the main front speakers. By that I mean that you could lean on the fronts of the actual speakers if you chose to do so. At that position the music was bordering on uncomfortably loud - with earplugs - and certainly far above safe limits without them. Don't assume that you won't be subjected to dangerous sound levels... or that, at some concerts, there will even be a spot in the far corner that is not uncomfortably loud. You're much better off always having a set of earplugs along in case you need or want them.

    And, no, I don't think cannons are a standard instrument for most symphony orchestras. But I'm also pretty sure I've read of at least one recording of the 1812 Overture that did feature real cannons - presumably firing blanks. It was recorded, and you can buy the recording, although I've never heard it personally.

    And, yes, some people do like to listen to music at dangerously high levels.
    I distinctly recall a customer returning a small pair of our powered speakers "because they wouldn't go over 118 dB in his listening room".

     
    Last edited: Jun 15, 2019
  10. TheSonicTruth
    The Telearc release is supposed to feature real cannons.

    I'll keep saying it - without shame - but if ear protection is needed at any spectator event besides airshows and car races/monster truck, then something is wrong.
     
  11. KeithEmo
    I kind of agree....

    However, the fact remains that many live events are unpleasantly, or even dangerously, loud....
    In many cases, the band, and/or most of the audience, prefers it that way....
    Some are hust poorly laid out - and, in order for the people in the back to hear at all, it's going to be too loud in the front.
    In others it is situational.....
    In the concert I mentioned, and many others, there were certainly areas where the sound level was reasonable, but the choice was between "dangerously loud" and "bring binoculars".
    (Whether we happen to agree or not... in most rock concerts "the good seats" is synonymous with "the really loud seats".)

    There is also a big difference between the situations you commonly encounter with classical and popular or rock music.
    With classical music, the performance will often be at a symphony hall, or some such venue with excellent acoustics.
    And, in addition, you will often have choices - for example, to avoid the local hall that you know is always loud, or to choose seats towards the back.

    However, with a popular rock or heavy metal group, on tour, they are often only at one venue in a given area.
    And, in many cases, that venue is either a multi-purpose stadium, a sports arena, or a bar that offers live bands.
    And, with many bands that tour, they may only appear in one place in each area, and quite infrequently - especially if you live outside a large metropolitan area.
    Therefore, if you want to hear your favorite band live, you may have little choice beyond "go or stay home".
    And, personally, I'd rather have earplugs in my pocket, and maybe need them, and put up with the compromise in sound quality, than miss my favorite band altogether.
    It's just one of the unfortunate facts of mnodern life - like cell phones dropping calls.
    (Sure, I'd probably attend more live concerts if that wasn't the case, but it is what it is.)

     
    analogsurviver likes this.
  12. bigshot
    To some people an anecdotal impression is an invitation to perform controlled tests to verify it. For others, anecdotes are all they need, especially if it validates their preconceived bias. Similarly, absolute extremes are only relevant at the North Pole, in an anechoic chamber or in a space station, not necessarily in a person's living room. Yet some people are more concerned with extreme examples than ones that hold true for the vast majority of circumstances. Again, it helps if the extreme example validates.
     
  13. analogsurviver
    I have been - unfortunately - to many shows that went past any reasonable SPL - and, given the correct legislation, would have put he perpetrators out of bussinbess for sure.

    In my late teens, I had a infection of the right ear. And after that, for years and decades, any excessive bass has been giving me pain in the right ear - within minutes.
    I remember leaving Wishbone Ash concert - after the first song - around 1979. It was unsupportable; not only me, many others have complained, endured a few more songs, and eventually left. Too much is too much.

    Recently, in 2017, it was Phil Niblock https://en.wikipedia.org/wiki/Phill_Niblock - at Sajeta festival. The "drone" music accompaniying his movies in a cinema theatre NEVER went below about 80- 85 dB SPL - and I would have to check the actual file, but IIRC "dynamic range" averaged below 10 dB, with an ocasional "peak"of maybe 15 dB. I have been appaled that he DEMANDED these high levels - for a non stop one hour or so. I have been to his concert three times - first, last and never again. Had ringing in the ears lasting to the next morning...

    Compared to that, rock/alternative/electronic/whatever music that followed has been - a relief... And no, it is NOT purely subjective assesment of levels - metering on Korg recorders is quite OK , and I had to use the lowest gain settings on mike preamp available to avoid overload - just barely. After that, the levels - even the peak, let alone constant - have been considerably lower.

    SPL meters that do give meaningful results are quite costly - particularly those that can accurately measure below 60 dB SPL. Regardless which "number" we assign to the loudness of music, the really relevant figure is average SPL over larger period of time. A normally compressed acoustic recording with dynamic range below 50 dB would actually register louder than the non compressed version of the same recording - despite non compressed version registering considerably higher peaks. No one would count drum rim shots as being particularly loud - but, in fact, there is little else that registers with such peak SPL - simply because the duration of rim shot is so short.

    Reproducing such uncompressed recording requires MUCH more powerful amplifiers - and whatever transducer at the end has to be capable of playing it back without severe limitations.
    A typical commercial recording might get away with less than 1/3rd of the peak output capability - but still sound subjectively louder than non compressed recording played back with equipment that can do it justice.

    A good example of great recording that is anything but squashed by loudness wars is https://www.discogs.com/Bill-Berry-And-His-Ellington-Allstars-For-Duke/release/3551938 It WILL clip the amplifiers that are thought to be "powerful enough" with regular commercial recordings - particularly brass. I can vouch for the original direct to disk release only; few samples in digital are available here : http://www.kreiselsound.com/downloads_1.php
     
  14. TheSonicTruth

    That expression makes me want to VOMIT. (Nothing personal Keith!)

    Anything of human origin or design can be changed if enough folks give a damn.

    So then what "is what it is"? The sun, for that matter. Many millions of years from now, it will run out of fuel and go super nova.

    It cannot be stopped. Unnecessarily loud concerts, or church worship, can be.

    The best way to protest is simply to not go - even if it's a once in a lifetime appearance in your hometown. Second best? Write the show organizers, or the artist's management, and tell them you don't like it so loud you need hearing protection.

    Keep that wave of resistance going!
     
    Last edited: Jun 15, 2019
  15. analogsurviver
    It , unfortunately, IS at it is.

    They have sold a s..tload of CDs by a VERY popular female singer - and only one friend and myself have been complaining for being clipped sky high. Only to be pitied by the staff ( including one ex-colleague ...) and being brushed off by : " ... you're just too old ..."

    I know a guitar player that would crank it up to and beyond the capability of the sound equipment - and when I first complained in private, but then in public, he turned his nose up, probably thinking what right do i have to interfere with his artistic freedom.

    Concert organizer are doing concerts for PROFIT - and in order to do that, they have to reach large enough audience. And if the audience is mainly young and not (yet) concerned about their hearing and more or less expects and demands it LOUD, that is what concert organizers have to provide - or someone else will do it for them. We can "resist" as much as we may , we may be as right as it can be - majority will have it its way. The show will go on with or without us...

    I am glad church worship here has not gone THAT loud as it has , obviously, the case in your neck of woods. That is, or should be, possible to rectify with the local church people ; but it is next to impossible with amplified live concerts, where money is at stake.

    So... - which ear plugs are considered not too detrimental for SQ and do not cost an arm and a leg ? Many musicians I would still like to see performing live won't be around forever - and the concert in (censored) acustics hall at herendous levels is likely the only chance I will ever get.
     
    old tech likes this.
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