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Post by Deleted on Apr 26, 2012 23:34:13 GMT
It's just that we don't ever think about all of the other things besides a file's contents. The file header stored by the O/S, the method of allocation of the contents on the disc or other media, various other things. If I send a file to six people, and each one of them does a "save as" to their computer using the same filename, that eliminates one factor of difference, but not others. Hi Dale, Unfortunately I do think about other things. Obviously filenames can not make any difference. I could write a program that does alter content depending on the filename but why would I do that for a audio program. You start mixing in other factors and computers, and even when the checksummed contents are the same, you may get differences. No.
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Post by Deleted on Apr 26, 2012 23:53:06 GMT
That may indeed force something to occur in the transmission that keeps the bits ordered a certain way when written to the destination disc. Now the checksum program will of course use the Operating System facilities to get the bits from the file in the order that the FAT or NTFS etc. table says is the correct order, and thus the checksum will be consistent, the same each time hopefully. But while the music players certainly would also depend on the O/S to read the data in the correct order as well, certain anomalies are possible. The older programming languages like 'C' offered several methods of reading data, not just one. Buffers come into play also, and while you would expect that a modern O/S like Windows or Mac to have resolved all possible buffer conflicts long ago, I can tell you that our database systems like SQL Server and Pervasive SQL for PC's are not 100 percent perfect in that regard - and I'm not talking about transaction processing either - just the ordinary stuff. SQL systems gain a lot of performance by grabbing a lot of sequential stored data that may be discarded when it extracts what it needs from the stream it reads. Some of those systems may use drive access methods that are lower level than what a file allocation table would support reliably. I can't prove anything there without a bunch of research to get article links, but the principle is valid. If your computer is a good performer, your software would not have to resort to unusual methods to read and write data, but that doesn't mean that your software would automatically scale up to a more reliable method just because more power is available. Hi Dale, TCP/IP doesn't understand file contents. It just concernes itself with sending and receiving packets of data, in the right order and with a checksum. I believe modern computers do this on the network cards. RE: SQL You are making this way to complicated. Audio playback is a simple program on a single user PC reading one or two files at a time. A modern PC can do this with no trouble. There is no database server, usually no networking, no multi users, no 100's of files open, no network security, no routers, switches or, firewalls, etc.
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Post by dalethorn on Apr 27, 2012 2:45:22 GMT
It's good to know I can feel safe about all of these things, Greg. If you take a look at dalethorn dot com and see my work there, I'm at the top tier in computer file manipulation and so on (not to brag or anything useless like that). So I do have a handle on the issues, but my occasional brush with logic and the unexpected has taught me to not say "It can't happen because things don't work that way". I do agree in principle that if two files compare exactly (using for example dale's Diff code), they are the same. And for most or nearly all practical purposes on my computers, filenames don't make a difference. But for me to project that onto software I can't evaluate at length for anomalies, I decline to do so and hold out the possibility that anything can happen. Murphy's Law.
I'm not going to lose any sleep over this, but I am curious about where the audible differences are coming from, and whether someone can construct a reliable test. So far, it's been obvious to me that any file I copy onto my computer is being written with the normal O/S services, and if a second or third file is so written, regardless of source, and contains the same bytes in the same order, then it will be the same and sound the same. But that's my computer. I'm not prepared to say that everyone else will experience the same thing. I can suggest that *very* likely if someone else writes two files onto their computer that have the same content, and by writing I mean unpacking a zip or otherwise copying from somewhere, they would sound the same. But ripping files that have the same byte content that sound different? It's not intuitive from the perspective of someone like me who is rooted in 30 years of high-tech software development, but if they sound different then I say "look for the difference - it must be there somewhere".
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Post by Deleted on Apr 27, 2012 3:53:09 GMT
Thanks for the post Dale, makes a lot of sense. It sounds like you pip me by a few years on IT experience, only my first few programs were written on punch cards before the Decwriter came along. I agree anything is possible in a once off, random instance, but if it occurs in a reproducible manner, it has to be able to be explained.
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Post by Deleted on Apr 27, 2012 7:05:25 GMT
Copying and transferring files and getting all bits in the correct order and value (1 or 0) is not the problem at all. It ONLY becomes a problem when ANALOG restrictions, such as bandwidth, interference from outside, noise that exceeds decision levels (or ringing) or jitter becomes so grave that bits alter.
If a bit it altered somewhere in the 'audio stream' and it's only 1 or 2 times this might go completely unnoticed in the resulting audio depending on where that bit is located in the data word(s), in other word WHAT that bit represents/means. Not all bits in an audiostream are 'audio related' there are a lot of control bits and incase pictures or songtext is included or additional info and a bit is altered in these bytes this will go unnoticed for the audio part (checksum could give that away but not all players look at that) If a bit is altered in the audio related data the effect too can vary between a 'tick' and 'inaudible'. If it happens a lot multiple ticks, dropouts or a 'stop' (freeze) may occur.
BUT this is NOT what THIS is all about.
There is another aspect that (in some cases) also has an influence but does NOT have influence on software handling at all. These are only hardware related problems and involve timing.
This is where the speculative culprit lies as we know bit perfect files are just that. Every bit is accounted for and these determine the actual described waveform.
It is beyond all doubt and can easily be shown that the described waveform is always the same in all those files.
Now the timing (jitter aspect) is another matter as that may or may not influence the ACTUAL waveform that comes out of the DAC depending on HOW data is handled and clocked out.
The data value itself (the famous 1 and 0) is always determined in a small window that is shortly opened (sampled as it were) at double the speed of the bit and is determined by the clock frequency. This works like a charm and makes sure the bit is determined correctly. That clock may be a separate signal or derived from the leading (or trailing) edges of the data signal in case this is a hybrid signal. SPdif is one of those, regardless if it is optical or electrical.
Now where the 'possible' differences between described and actual waveform COULD come from is if that SPdif derived clock or separate clock sort of wanders in time. In case of a badly designed DAC (with poor jitter rejection) which is not very common these days, that (derived) clock is used (cheap way) to clock out the aalog signal. In this case the sample itself could be outputted a fraction (nanoseconds) earlier or later. This would result in a marginal 'ripple' in the output signal.
Also noise on DAC related powerlines COULD influence the output signal (amplitude) if that chip has a bad PSSR or influence timing.
This can be verified (and has already been done) by analog technigues where the analog signal is 'recorded' and compared to the described waveform. Technical obstacles however make this extremely hard to do and involves extremely expensive ADC and fast computers.
Anyway in this case it doesn't matter as it appears as if the differences originate at the RIPPING part. Simply because it is determined by ear that power supplies matter, drives matter, cables matter, PC (OS) matters, OS mode matters, ripping way and location matters, ripping program matters, data transport matters, data transport vehicle matters, data processing matters, and all 'analog' problems (that are supposed to be ruled out by digital) also appear to be present still e.t.c.
Now here comes the 'difficult' part for techs (those that are quite familiar with HOW bits are electrically determined and how the hardware AND analog work as well as how data formats on digital media are PHYSICALLY stored and retreived.
The difficult part is that yes 'we' do recognise and understand how jitter and timing aspects matter in the DAC (and ADC) domain and that power supplies matter (a bit) and for which cases and what circumstances. No secrets there. The technical problem is these timing aspects are ONLY relevant at the interface point from digital to analog and vice versa and have NO influence in the ripping or data transport and storage level as timing is NOT used in a sense that it can influence the described waveform (bit pattern) and if it does the effects are described above as bits would ALTER.
Since the reported differences can ONLY be 'verified' by ear and by certain people this makes it hard to analyse and to resolve this issue (real or placebo) we NEED to examine both variables. hearing/perception and the digital process. The latter is 'known' to techs so only the first variable remains. This is wehere the 'resistance' begins because a: it is insulting, they and others clearly hear it' b: in tech controled tests the differences magically disappear and the 'trick' can not be repeated.
Techs and hearing people separate again confirming both their 'convictions' and then gap remains.
IF ONLY that audible aspect were 'proven' beyond a level of much doubt (which I wish could happen but think will not) to those that can investigate the claims on an electrical/technical level and perhaps shed some light IF the differences are indeed perceivable.
FAT chance to see any cooperation on that level simply because of the 'conviction' that the techs are ONLY out to discredit, for whatever reason that might be mentioned.
a matter of trust.
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Post by Deleted on Apr 27, 2012 7:27:44 GMT
Hi Frans,
That was an excellent post and states the case pretty well.
May I just add, that those who do hear differences between files of identical checksums but different details in the method of ripping, are just as frustrated that there is no technical, measurable way of confirming the anomaly.
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Post by Deleted on Apr 27, 2012 7:33:05 GMT
The gap remains because certain "Techs" refuse to accept the findings of highly qualified engineers, who have a great deal of expertise in this area. There were 6 positive listening sessions involving Blind A/B/A/ 3 minute sessions. To suggest that the results were manipulated to achieve a particular result is insulting, especially as present knowledge would have suggested that all of the results should have been either negative or inconclusive. My co-operation in this area is still ongoing, just not with those who demand it.
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Post by Deleted on Apr 27, 2012 8:18:33 GMT
Chris, I can understand the frustration. I have been there myself (hearing and measuring not appearing to have FULL relevance). Alex, Well... let's put it this way.. IF these 'highly qualified engineers' are 'highly capable' as well they should have little problems finding out WHY. That is they could find clear proof that would satisfy the ignorant technical people that do not know what monster (digital audio) they created and how analog it still is despite its principle of operation. This is a bit sarcastical... I know. I wish you and the highly qualified engineers very much luck and hope they(you) find convincing evidence. Believe it or not, I REALLY like/want to know what I, and the rest of the technical community, missed. Judging from the track record of these 'highly qualified' engineers and how much resistance they get regarding their theories, views and testing methods from other (obviously less ?) qualified engineers in their own and other forums doesn't inspire much confidence to me personally. But then again... maybe they can prove me wrong. Anxiously awaiting their technical report/findings and hope they will submit to and pass AES/Hydrogen scrutiny afterwards.
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Post by Deleted on Apr 27, 2012 8:31:18 GMT
M.C. runs a relatively recent magazine and a forum. The magazine has no advertisers. This means that most tests are outsourced, and the budget is limited.You are also ignoring the independent findings of "screenmusicargentina"in the jPlay Forum, and he also mentioned loss of SQ after J.K. sent the files back to him, He was unaware of the findings of myself and J.K. at the time of the initial post. There is also a late report about one of the D.S. files that I UL for HFC members in the HFC Forum.The most recent poster has admitted that he didn't expect to hear any differences due to very average gear. Added to that, Chris sent me some comparison .wav files from Spain, and I correctly identified the Safe Mode File without knowing which was which.
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Post by Deleted on Apr 27, 2012 8:54:49 GMT
I know my 'ignoring' of the findings is what is bothering you and find dismissive and insulting. The J-play thread fizzled and I have not seen any test results nor disclosure of test methods and competences of the people participating, so pardon me if I don't take this very serious as independent 'evidence'. To you MC is a hero and will be also for many others as well. His magazine being advertising free is not relevant to THIS reserach as NO vendors are active in this field so see no relevance of this. To me (and MANY others) he is not nearly as 'qualified and noted' as he is to you. Did Chris sent 2 files with different names or 10 files which you had to pick the correct ones out of ? In the first test/comdition you are 100% sure to find differences and have 50% chance you pick the correct one. In the last case we can speak of blind testing, not double blind, and has statistically more 'proving power'. I will have to take your word for it then and accept it is real despite what every fibre in my being tells me.. This requires and act of faith (as in religion) by simply accepting, without doubt nor any evidence, other than claims or hear-say. In court it wouldn't fly in any case. I am afraid your beyond all doubt evidence is good enough for you and many others but not for me (and others) for obvious reasons. www.stereophile.com/content/carver-challenge... a fun read with surprising conclusions as well.
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Post by dalethorn on Apr 27, 2012 21:25:36 GMT
I read the whole thing. Very nice. In my mind it adds some credibility to NaAvGuy's claims about a low-cost headamp design. The relevance to what's been discussed here also seems clear to me - i.e. to identify and reduce the differences people are hearing in ripped tracks is going to require a team on site where the rips take place, just like the Stereophile team and Bob Carver.
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Post by Deleted on Apr 28, 2012 3:07:05 GMT
What a load of old codswallop ! They were comparing amplifiers from around 1985!!! Amplifier design has progressed a little in the last 27 years.Research by Douglas Self has also resulted in major improvements in many areas of amplifier design since then. They are talking about amplifiers that have S/N of -100dB and .1% distortion both channels driven . I couldn't even find channel separation figures. The new SC ULD3 for example, is quoted at <.0025%,1kHz ,20Hz- 22kHz bandwidth, 90W (both channels driven. S/N is around -115dB WRT 90W into 8 ohms. Even the SC ULD3 quotes a miserable channel separation of around 50 dB, and it seems highly likely that these oldies were no better. They wouldn't even come remotely close to the Halcro reviewed here.
TNT-Audio BEST OF SHOW by Richard George While there were many exhibits that were entertaining and informative, there were two that stood out due to the quality of audio output and despite limitations of the hotel suite environment: The Australian audio company, Halcro, demonstrated their DM68 Super Fidelity Monoblock amplifiers at the Tuscany Hotel. Rated at 225 watts per channel, but with headroom unmatched by almost any amplifier, the DM68 was designed to drive any loudspeaker on the market. The specifications are impressive, including total harmonic distortion of 0.000001%, and a power factor corrected power supply that will operate on 85 to 270v, without any internal or external switches. However, specifications don't tell the whole story. The dynamic range and tonal balance were superb. More to the point, the music reached into the room and enveloped the listener with a presentation that was involving and moving. What more could you ask for? If only multi-channel audio could surround the listener with music in the same manner as a pair of Halcro DM68 monoblocks. The DM58,a slightly less powerful version of the same design, also was demonstrated. The sound quality was almost as good as the DM68.
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Post by Deleted on Apr 28, 2012 8:51:34 GMT
You funny guy. ;D speaking of a load of old codswallop ! 0.000001% means a S/N ratio of 160dB ! That'll be the day. You could print those figures in 'SandyK's joke of the day' instead of being 'informative'. When you want to impress people you better print the actual figures: 0.0002% = -114dB hmmm... that looks more realistic. 85-260V is a quite common voltage range for switch-mode power supplies (called a wide range power supply) And what do I detect ? ... a briliant amp with an SMPS, surely that can't be good ! SMPS= BAAAAAAD ;D I wonder who could tell it apart from any other amp when tucked away behind a curtain... more recent (2006) old codswallop: www.matrixhifi.com/ENG_contenedor_ppec.htmBut you are perfectly right though the test is old but funny.
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Post by Deleted on Apr 28, 2012 9:04:10 GMT
Whatever you say Frans. Whatever you say.... I suggest that you do a bit of reading about Bruce Candy's highly unusual Halcro designs , that also use RF techniques IIRC. He also has a 1999 patent that incorporates a diode between the normally tied b and c junction of the typical Current Mirror.That is part of one method of front end balancing that RG member david2vk has been using for some time before that. Yeah. Funny, peculiar. ;D Attachments:
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Post by Deleted on Apr 28, 2012 11:39:33 GMT
Urmm no... The diode has nothing to do with front end balancing techniques at all. Front end balancing is done here with part 13 and 14 and is very similar to what's found in most newer opamps and you can also find this in most textbooks about amplifier design b.t.w. and is not what's so 'special' about this design. I even suggested 'similar' front end balancing for a certain circuit b.t.w. as it doesn't require any adjustment and is always perfectly balanced. You see, for the best behavior of a front end it is not only 'important' to have the voltages the same but also as low as possible. The design above incorporates this low front end voltage technique and uses a hybrid input transistor as well. The patent here has to do with a different kind of implementation of the old NAD power envelope technique with 2 voltage rails. ???Has nothing to do with double blind testing b.t.w.. This design could just as well be behind the curtain in the above mentioned test instead of one of the other amps. Who knows what would have happened then... But you are probably right again. I could use some brushing up in my analog electronics knowledge. Too bad technical matters and audio don't seem to go hand in hand though.
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Post by Deleted on Apr 28, 2012 12:23:05 GMT
Unless I am mistaken,the diode helps to equalise the voltage drops across both halves of the Current Mirror. At least it does in david2vks version of our front end balancing in conjunction with fine tuning of the VAS current. Your suggestion would have needed another relatively expensive dual transistor and a complete PCB redesign. The present design has been found to work quite well, even in the colder U.K. climate after correct initial adjustment. Here we go again, more of the usual sarcastic crap. You must be still smarting after coming unstuck with your 1985 amplifier design comparisons reference . It would appear that you need a trip in the attached. P.S. Sorry to spoil your fun, but I'm going to bed! Attachments:
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Post by Deleted on Apr 28, 2012 12:47:43 GMT
What card will you pull out of the proverbial hat next to trump that ignorant EE ? Partly mistaken would be the more correct definition... It is part of the current mirror circuit though and a different implementation as used in the mentioned design on top of that. I still keep wondering what would happen if we stuck that amp behind the same curtain... Ah.. we'll never know ... (sarcastic) Would more designs be found to work well in the Australian as well as the U.K. climate ? (again... sarcastic) Our ears also have evolved in the last 25 years so while we couldn't detect 'added sounds' below -80dB, human hearing fortunately is now capable of detecting anomalies below -120dB. (oops also sarcastic) Now.. while you are sleeping I am going to browse my music collection in search of recordings with these kind of noise and distortion levels (-120dB) and really enjoy it on my 'transparant' gear. (dammit... more sarcasm) Not having to question if I had only replaced that ....(fill in your personal favorite tweak part) so sonic bliss would be markedly improved.
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Post by Deleted on Apr 28, 2012 22:18:29 GMT
Keep digging that hole and you will beat Sir Richard Virgin to the centre of the earth ! ;D
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elysion
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Post by elysion on Apr 28, 2012 23:14:22 GMT
Did I miss anything? The rumble in this thread was sensible even over here in Switzerland. ;D At least a 9.1 on the Richter magnitude scale. (Myself seeking save cover in other threads.)
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Post by Deleted on Apr 28, 2012 23:32:56 GMT
Did I miss anything? The rumble in this thread was sensible even over here in Switzerland. ;D At least a 9.1 on the Richter magnitude scale. (Myself seeking save cover in other threads.) Christian Do you seriously believe that amplifiers designed in 1985 (27 years ago) as per the Stereophile link, would sound exactly the same as the best of the modern amplifiers, especially after all the research done in the last 10 years or so by prominent Audio designers, and authors such as Douglas Self from the U.K. ? Douglas Self is unashamedly anti-subjectivity, but I think that even he, after at least 5 editions of his Audio Power Amplifier Design Handbook would be pretty pissed to find that all of his efforts had been in vain. Kind Regards Alex
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Post by Deleted on Apr 29, 2012 7:40:43 GMT
Ignoring the 2006 test again ? The latest amplifiers may measure better (have lower distortion/noise figures) BUT can it be discerned behind a curtain ?... that's the question. about the deep hole I was diggin'... is it behind curtain number 1 or number 2 ? ;D 50% chance you fall in the deep hole, 100% chance you are taking a gamble. ;D
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Post by clausdk on Apr 29, 2012 7:42:45 GMT
Better or worse I can not say, but i KNOW that some of those old Tandbergtape players give the modern Headamps a serious run for their money.. So they were able to make good amplifiers when I was a young man.. I better run for cover now.. Did I miss anything? The rumble in this thread was sensible even over here in Switzerland. ;D At least a 9.1 on the Richter magnitude scale. (Myself seeking save cover in other threads.) Christian Do you seriously believe that amplifiers designed in 1985 (27 years ago) as per the Stereophile link, would sound exactly the same as the best of the modern amplifiers, especially after all the research done in the last 10 years or so by prominent Audio designers, and authors such as Douglas Self from the U.K. ? Douglas Self is unashamedly anti-subjectivity, but I think that even he, after at least 5 editions of his Audio Power Amplifier Design Handbook would be pretty pissed to find that all of his efforts had been in vain. Kind Regards Alex
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jkeny
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Post by jkeny on Apr 30, 2012 21:58:28 GMT
Frans, You did a great post no 29 above - at least for the first half of it, it was great - then you went into mis-statements & mis-information. Pity I wasn't around when you posted it but it's probably too late to drag it up now. You know I believe if we were put in the same room we could come to some mutual agreement Anyway, here's what I want to introduce: - Firstly, has anyone here actually ever been involved in a REAL, SCIENTIFICALLY CONTROLLED DBT? I haven't but I've read that their requirements re onerous & costly. They seem to me to require very, very strict control of any factors that might influence the outcome. - In the absence of running one of these DBTs, can somebody provide me with the evidence that removing sightedness is the most important bias? I mean is there some scientific evidence that this has the highest biasing factor, as opposed to other biases? It would be good for those that insist on this approach to provide the evidence. Or are we just fooling ourselves by thinking that we have removed the major bias but really the actual real bias is psychological & just not as evident? What about monetary, what about emotional - I'm no psychologist but I'm sure a psychologist would be able to give the breakdown on this? - Yes, I use informal blind testing for when I want to verify that sightedness is not influencing me but I'm just as happy to take the evidence of a largish number of anecdotal reports which concur with what I hear. I don't insist on blind testing - some things are blindingly (pardon the pun) obviously different.
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Post by dalethorn on May 1, 2012 1:08:10 GMT
Seeing is a problem. It distracts from hearing at the very least. I don't think that requires any proof.
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Post by Deleted on May 1, 2012 7:40:11 GMT
Frans, You did a great post no 29 above - at least for the first half of it, it was great - then you went into mis-statements & mis-information. In your point of view I can see why that would be your opinion. Anyway, here's what I want to introduce: - Firstly, has anyone here actually ever been involved in a REAL, SCIENTIFICALLY CONTROLLED DBT? I haven't but I've read that their requirements re onerous & costly. They seem to me to require very, very strict control of any factors that might influence the outcome. DBT are very costly and not needed IF you are serious about the test. When you make your own DBT machine (PC and driven relay board) it can be done at little cost. Point is DO you really want to know ? I did.. it 'cost' me a lot of time and a lot of things I valued to be true in audio. Didn't take away the fun though, just increased it AND got me interested in the field of perception. I have and conducted BT myself.. many times. Mostly with unsuspecting (and unknowing afterwards) customers and for my OWN verification. Also with interested people that make 'bold' statements. Simply leave out the knowing part and/or tell them something changed (pokerface obligated or hide behind equipment) and await the responses... very fun to do (IF you are on the 'objective' side of the fence) They come at NO cost at all, pokerface and cunningness is needed... well not if the test subjects are unaware. - In the absence of running one of these DBTs, can somebody provide me with the evidence that removing sightedness is the most important bias? Oh, simply surf the web with terms like perception and read the MANY MANY articles out there. What I did was test myself... gives you more insight in yourself and hearing than just reading opinions. You'd have to be very open minded for this to accept the results of your own tests PLUS you would have to fully understand HOW to create/do valid tests. - Yes, I use informal blind testing for when I want to verify that sightedness is not influencing me but I'm just as happy to take the evidence of a largish number of anecdotal reports which concur with what I hear. I don't insist on blind testing - some things are blindingly (pardon the pun) obviously different. I don't take any largish number of anecdotal reports which concur serious. Reason is very simple and fell for it many times (and still do). IF one person can 'hear' something that MIGHT not be there is there any reason why any other human being cannot experience the exact same (perceive the same)? Afterall you might have seen many of those fun optical illusions where things start to rotate (on printed paper where we consciously KNOW it doesn't move) or see dots where they are not there e.t.c. Everyone falls for those things (same with tasting and seeing products that only have a color added) you cannot help it and is the same for everyone (the effect). Also one tends to 'replicate' mods already described or buys on reviews and reads on what to expect. One can always say one is NOT influenced and may even consciously expect the opposite (because of conscious convictions something cannot matter by lack of knowledge in general). In the back of the mind (WHICH SETS the bias, not conscious levels) the 'damage' has been done. This effect is well documented b.t.w. (at least in my opinion) Problem of blind testing is it is only valid as 'evidence' when both believing and skeptic party are present to 'oversee' and log th results. Otherwise they are for your enlightment only. You believe in subjective testing where sighted may or may not be a problem, based on your experiences. I believe in tests where the knowing part is taken away, based on my experiences. As far as I know of the many tests where both camps joined forces (and are conducted and accurately logged/reported) the claimed differences in ..... could not be detected by any party. If one looks hard enough maybe one or two tests might prove different but there might be a good reason for that. a matter of opinion and preference.
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