Do you hear a difference?

[Jean-Marie]

Every ABX studies have shown the same results, and they are the only ones eliminating expectation bias, that we all have whether we like it or not.

By the way, if frequencies above my hearing threshold can produce something that I can hear, this is not very good news for the quality of my reproduction chain, because it means that I have somewhere non linearities that are spilling back in the audible band.

I know that physics is counter intuitive in that case, but the closest your system is to perfection and linearity, the less likely you are to hear any difference between a red book and a higher resolution rendition of the same master.

Jean-Marie

The whole area of testing in audio is fraught with disputes and there are a lot of disputes about a lot of things. There isn't universal agreement about the accuracy/reliability of ABX testing but there isn't universal agreement about the accuracy/reliability of any other sort of testing protocol either. 

If you doubt that frequencies above your hearing threshold can produce effects in your audible range, look at the plots for the sort of tests I mentioned in John Atkinson's reviews in Stereophile. You'll see lots of distortion artefact spikes at 1 kHz intervals from 1 kHz on up from intermodulation between a 19 kHz tone and a 20 kHz tone. Are they audible? Take a look at their level relative to that of the 19 and 20 kHz tones. Audibility will depend on the level of the 2 test tones. Note that those test results apply to distortion produced in our gear. Now take a look at the distortion specs for your Devialet. They're well below the audibility threshold and my Devialet is the cleanest sounding amp I've ever owned. If I can hear distortion in my system it isn't coming from the Devialet but from somewhere else and I don't notice any distortion.

If you can find a copy of the Meredith Monk album "Our Lady of Late" and play the track "Slide" you will hear the tone of the wine glass she's rubbing and the note she's varying as she sings, and a third note which will appear to come from inside your ears. That third note is intermodulation occurring in your hearing. The note of the wine glass and that of her voice are well within the range of your hearing so this doesn't prove that you will hear something produced in this way if one or both tones are outside of your hearing range but it does demonstrate very clearly how 2 tones can generate a distinct and different third tone and the Atkinson test plots show that tones above the hearing range for most of us can produce tones that are well within the audible range. Is this a problem? I don't hear lots of people raising reports of problems of this kind and that says something, in fact it says a lot.

My point was simply to say that assuming anything above 20 kHz can't have an audible effect because it's outside our hearing range is problematic because sounds outside our hearing range can generate effects within the range we can hear. The question is how noticeable the difference between CD quality and higher resolutions is and we don't have a clear answer on that in my view. I buy high res files of music I really llke because I think I hear a difference, a subtle difference but one I like, and I can afford to buy the files. If I had the gear I had 20 years ago I doubt I would hear the difference I think I hear and I wouldn't be buying high res files. I'll tell people that I think high res makes a difference but I won't tell them that it's proven that it makes a difference. I try to be honest about the state of the debate. That's the best I can do. I weighed in here with my original response simply because assuming that anything above 20 kHz CAN'T make a difference because we can't hear above 20 kHz is overly simplistic when that fact was determined with single test tones and almost every piece of music involves harmony, ie several tones at the same time, and when 2 or more tones occur simultaneously intermodulation products can be generated within the audible range. That means that there may be some audible effects from sounds in music which fall outside the accepted range of audibility. I have no doubt that any such audible effects are going to be subtle but they are theoretically possible.

I'll tell one story to illustrate the difficulty of testing for audibility of effects. Years ago when Sony and others were trying to come up with copyright protection strategies for CDs, people were trying to devise "watermarks", signals which could be buried in the audio signal on a CD and identified in copied material but the problem was designing a watermark which wasn't audible because an audible watermark would be regarded as a degradation and distortion of the music. Lots of listening tests were involved because that's the only way you can test for the audibility of a watermark. One company came up with a watermark they claimed was inaudible and they pointed to extensive, well conducted tests for which the results failed to show that the people tested could hear the watermark. They started demonstrating this publicly by conducting demonstrations at audio shows and giving the listeners a card on which they could record their results with those results being analysed and reported to the participants at the time. Several of these demos were apparently conducted with the same result, no proof of audibility, and then at one test where the collated results showed exactly the same thing there was one participant who got every test comparison right. That was a non-random result par excellence. They asked that participant what he was listening for and hearing and he told them. Once they knew what to listen for they heard it also, and anyone told what to listen for could also hear it and get every test right. The watermark was most definitely audible but people who didn't know what to listen for and who weren't listening for it didn't notice it. Audibility is a complex issue and designing and conducting really good and reliable tests is most definitely not easy.

If you want my definition of a really good, reliable test then I'd say it's a test that puts the dispute to rest, one which delivers a test which everyone accepts. It can be done but it can take a lot of time and a lot of money and a lot of tests which don't put the issue to rest in order to come up with a test process that can deliver the goods. There have to be reasons other than simple academic or scientific interest to go to those lengths and those reasons tend to boil down to the return you can make on the investment it takes to get the result. That kind of return on investment usually isn't found in the audio business so if we're going to see that sort of test then it's going to have to be conducted for other reasons than the one we're interested in. These days that's likely to mean that it's going to have to be related to something like electronic surveillance for military or security purposes and it could take some time for people outside those areas to become aware of it. 

For what it's worth I'd love someone to produce a study that resolves the question regardless of whether the result says that I was right or that I've been wasting my money on high res files. Audio advances when disputes like this get clearly resolved and I'm in favour of that. The prospect of being wrong doesn't worry me. I've been wrong and spent money in audio on things I later decided weren't worth it before. No one gets it right all of the time. 

The only thing you said that I might disagree with you on is your statement that "the closest your system is to perfection and linearity, the less likely you are to hear any difference…". In my experience the better your system gets the less it masks subtle differences and the more likely you are to hear small differences you didn't notice before.

I’m fully aware that two tones can combine to generate lower tones. However if you can hear it, it is because it is in your hearing range. And if it is, it will adequately be captured and produced by the chaîne limited to your hearing threshold. 

My point is that anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording. If a higher recording leaves you hear something different, this is something that is produced by the non linearities of complete chain, creating artifacts in the audible bands that were not there if you were listening to the real thing. 

I’m sorry, physics is a hard science and cascading 3 low pass filters: the one in the ADC, the one in the DAC and our ear is dominated by the lowest one which is our ear. 
In that case, the only way to have higher frequency than this lowest low pass filter to have any effect is to have non linearities before that last filter. 

Jean-Marie

[David A]

I’m fully aware that two tones can combine to generate lower tones. However if you can hear it, it is because it is in your hearing range. And if it is, it will adequately be captured and produced by the chaîne limited to your hearing threshold. 

My point is that anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording. If a higher recording leaves you hear something different, this is something that is produced by the non linearities of complete chain, creating artifacts in the audible bands that were not there if you were listening to the real thing. 

I’m sorry, physics is a hard science and cascading 3 low pass filters: the one in the ADC, the one in the DAC and our ear is dominated by the lowest one which is our ear. 
In that case, the only way to have higher frequency than this lowest low pass filter to have any effect is to have non linearities before that last filter. 

Jean-Marie

I- What's physics got to do with it? We're talking about what we hear and that gets studied in biology and neuropsychology which are different fields entirely. Physics is relevant to the sounds produced by our gear but when it comes to whether we can hear a difference between high res and CD quality recordings physics tells us about what the differences in the sounds produced by those recordings are but not about what we hear when we listen to them.

2- what's the relevance of the 3 cascading filter bit? I've never suggested we can hear anything outside our hearing range so the fact that our ears are the limiting factor is something I've acknowledged from the start.

3- you can hear lots of things in a CD quality recording that you would not have heard at the live performance and many of those things have nothing to do with non-linearities. They're due to differences in the sensitivity of the mics to the sensitivity of your ears, to the differences in where the mics are located to where you sit, to how multiple channels are mixed in recordings and the ways in which the engineer adjusts the levels from different channels which can easily produce a different balance in levels between instruments and voices than you would hear at the performance, and how the eventual recording is finally mastered. And all of those differences are irrelevant if what we're discussing is differences between 2 recordings of different resolution.

I have a university qualification in a health science related field. I've had to design and conduct a research study in order to get that qualification, I've presented those results at a scientific conference and I've had them published in a peer reviewed journal. It wasn't great or ground breaking research but I had to follow standard scientific practices so I do know something about the scientific method and all of that.

Do me a favour. Stop misrepresenting what I've said. Go back and read it carefully. I've never claimed we can hear things outside our hearing range or anything like that or what you're implying I said. And don't make ridiculous statements like "anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording" which are patently untrue as any recording engineer will tell you, and the reason it's untrue has nothing to do with physics or non-linearities.

There is still no widely accepted scientific evidence that we can hear differences between high res and CD quality sound but there's also no evidence that we can't hear differences. People are still arguing about it and people are still conducting tests. The jury is still out. I have been at pains to avoid saying that there is a difference though I have said that I think I hear one which is a very different claim. I also said that I could be mistaken and that I'm not trying to convince anyone to start buying high res recordings.

I've been as scrupulously honest as I can be in what I've said. Why don't you try being as honest about what I've said as I've been and why don't you stop making statements like "anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording" which are simply wrong.

[Jean-Marie]

I’m fully aware that two tones can combine to generate lower tones. However if you can hear it, it is because it is in your hearing range. And if it is, it will adequately be captured and produced by the chaîne limited to your hearing threshold. 

My point is that anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording. If a higher recording leaves you hear something different, this is something that is produced by the non linearities of complete chain, creating artifacts in the audible bands that were not there if you were listening to the real thing. 

I’m sorry, physics is a hard science and cascading 3 low pass filters: the one in the ADC, the one in the DAC and our ear is dominated by the lowest one which is our ear. 
In that case, the only way to have higher frequency than this lowest low pass filter to have any effect is to have non linearities before that last filter. 

Jean-Marie

I- What's physics got to do with it? We're talking about what we hear and that gets studied in biology and neuropsychology which are different fields entirely. Physics is relevant to the sounds produced by our gear but when it comes to whether we can hear a difference between high res and CD quality recordings physics tells us about what the differences in the sounds produced by those recordings are but not about what we hear when we listen to them.

2- what's the relevance of the 3 cascading filter bit? I've never suggested we can hear anything outside our hearing range so the fact that our ears are the limiting factor is something I've acknowledged from the start.

3- you can hear lots of things in a CD quality recording that you would not have heard at the live performance and many of those things have nothing to do with non-linearities. They're due to differences in the sensitivity of the mics to the sensitivity of your ears, to the differences in where the mics are located to where you sit, to how multiple channels are mixed in recordings and the ways in which the engineer adjusts the levels from different channels which can easily  produce a different balance in levels between instruments and voices than you would hear at the performance, and how the eventual recording is finally mastered. And all of those differences are irrelevant if what we're discussing is differences between 2 recordings of different resolution.

I have a university qualification in a health science related field. I've had to design and conduct a research study in order to get that qualification, I've presented those results at a scientific conference and I've had them published in a peer reviewed journal. It wasn't great or ground breaking research but I had to follow standard scientific practices so I do know something about the scientific method and all of that.

Do me a favour. Stop misrepresenting what I've said. Go back and read it carefully. I've never claimed we can hear things outside our hearing range or anything like that or what you're implying I said. And don't make ridiculous statements like "anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording" which are patently untrue as any recording engineer will tell you, and the reason it's untrue has nothing to do with physics or non-linearities.

There is still no widely accepted scientific evidence that we can hear differences between high res and CD quality sound but there's also no evidence that we can't hear differences. People are still arguing about it and people are still conducting tests. The jury is still out. I have been at pains to avoid saying that there is a difference though I have said that I think I hear one which is a very different claim. I also said that I could be mistaken and that I'm not trying to convince anyone to start buying high res recordings.

I've been as scrupulously honest as I can be in what I've said. Why don't you try being as honest about what I've said as I've been and why don't you stop making statements like "anything that you would have heard being present in front of the real thing, you will hear it from a 44.1 kHz recording" which are simply wrong.

David,

If I had offended you, please accept my apologies since it was not my intend. 

I will stop on the topic, since I don’t want to risk spoiling this forum which so far has avoided the pitfall of uncourteous discussion and obviously my answers come across as such. 

Best regards,

Jean-Marie

[David A]

David,

If I had offended you, please accept my apologies since it was not my intend. 

I will stop on the topic, since I don’t want to risk spoiling this forum which so far has avoided the pitfall of uncourteous discussion and obviously my answers come across as such. 

Best regards,

Jean-Marie

Jean-Marie,

I'm sorry I responded so strongly but after trying to be as precise as possible in my comments in order to acknowledge the views on both sides, I was extremely unhappy about seeing an implication that I had made a claim I was at pains to avoid making in a response which also said that the issue was in the domain of physics which deals with the properties of sound waves rather than biology and neuropsychology which study our hearing, and that any differences between live sound and a 44.1 Hz recording come down to non-linearities in equipment which totally ignores the  many quite deliberate choices made by recording engineers and which are irrelevant anyway when the argument is about whether there are audible differences between 2 recordings rather than between a recording and the live event.

All this started our from my response to Pim's statement that frequencies above the range of a CD was inaudible because it was above our hearing range. I agreed that frequencies above the range of a CD were inaudible but pointed out that in combination with other frequencies they could generate tones in the audible range. I've never suggested that anyone can hear anything above the range of their own hearing and in fact I clearly stated in my response that I was not suggesting we could hear sounds above the upper limit of our hearing range.

I will add that in his post above, @Confused comments that suggestions have been made that it's the 8 extra bits in 24 bit high res files that contribute to any audible difference. That is a possibility and it has nothing to do with the upper frequency limit of our hearing range. Most of the argument keeps getting limited to the audible hearing range while ignoring the number of bits and they shouldn't be ignored since they contribute to the sound we hear from high res recordings.

I'll call it quits on this topic as well, for similar reasons to you. That's a pity because the thread started with a question about whether or not we could hear a difference with high res recordings. It appears that the only non-contentious answer to that question is that we're all still getting bogged down in arguments about that and that there is no agreement about the answer.