"SACD and DVD-A proven no better the CD in a year of listening tests"

http://theaudiocritic.com/blog/index.php?op=ViewArticle&articleId=41&blogId=1

Discuss!

And if this subject has caught your eye, David Griesinger's home page http://world.std.com/~griesngr/ should interest you as well, if you're not already very familiar with it.  Several weeks of reading to be had there on all sorts of audio matters.

Reading further I've now gone through the powerpoint document at http://world.std.com/~griesngr/intermod.ppt - and it makes really intriguing reading (and I think that the soundcard manufacturer beginning with "C" referred to in the document is well known here!).  The author concludes at the end of his presentation -

"Conclusions for “High Definition” Audio:

Adding ultrasonics to a recording technique does NOT improve time resolution of typical signals – either for imaging or precision of tempo.  The presumption that it does is based on a misunderstanding of both information theory and human physiology.

Karou and Shogo have shown that ultrasonic harmonics of a 2kHz signal are NOT audible in the absence of external (non-human) intermodulation distortion.

Their experiments put a limit on the possibility that a physiological non-linearity can make ultrasonic harmonics perceptible.  They find that such a non-linearity does not exist at ultrasonic sound pressure levels below 80dB.

All commercial recordings tested by the author as of 6/1/03 contained either no ultrasonic information, or ultrasonic harmonics at levels more than 40dB below the fundamentals. 

Our experiments suggest that the most important source of audible intermodulation for ultrasonics is the electronics, not in the transducers.
Some consumer grade equipment makes a tacit admission of the inaudibility of frequencies above 22kHz by simply not reproducing them.  Yet the advertising for these products claims the benefits of  “higher resolution.”

Even assuming ultrasonics are audible, loudspeaker directivity creates an unusually tiny sweet spot, both horizontally and vertically".

The author notes earlier that sample rates of 48kHz and above were largely justified by the limitations of early AD DA converters, but that even inexpensive converters were now able fully to reproduce all frequencies which can be proven to be audible in musical signals at 44.1kHz (I hope that summary is correct).

I suspect those wedded to 96kHz etc recording standards will not accept a word of this, however.  I've always been totally wedded to 44.1kHz as representing all I can hear (and more), and therefore of course I accept it with glee!

I'm with you 100%, Peter.

A couple of years ago I was listening back to a live concert recording of some chamber music which had been recorded multichannel at 24-bit with a back-up direct to regular audio CD-R. The replay was on a good hi-fi set up in a pretty poor listening room and the performers were mulling over their performance. Also present was a prat from the company which had supplied the recording equipment - he'd flown over from London to fix (again) the Tascam multitrack HDD recorder. Whilst we were trying to listen to the recording he kept blethering on about how obviously inferior the 16-bit CD was to his 24-bit recording, and couldn't we hear the 'graininess' in the sound from the CD.

I resolved never to consider buying audio equipment from his company...

So it ain't my ears and gear making me not hear any difference...

The only advantage so far I found is that "they" seem to take more care about those sacd/dvd-a recordings.

In the real world, the punters don't get to compare and contrast anyway.  For instance, over here the local radio stations each get to record the major touring classical performers in their city's major hall.  Some of these guys use pretty high-end equipment at 24/96, others use similar equipment at 16/44.1, others perhaps use less exotic equipment such as good old minidisc.

Occasionally we compare and contrast the results we've got, and there are inevitably significant differences - but those differences plainly arise from different mic techniques, different mics, different halls, different post-pro methods and tastes, etc etc.   Discerning amongst those variables the 24/96 recordings from the rest, even if you admit there are audible differences, would be a hopeless task.  And that's what the record-buying public are supposed somehow to be able to do, even to the extent of funding the costs associated with the more "advanced" ways of recording - whereas it's increasingly clear that in practice the bulk demand is for mp3.  The commercial case seems to me to be very hard to make.

Yep, I knew it: more snake oil, green markers, and welder's cable for mains.  Oh, what? We have some sensible science on the Internet?

The commercial case has been hard to swallow even for the small part of the public that cares.

So the Journal article isn't on the 'net.  That would be a good read.

But I like the idea that 1) higher bit depth gives more slop room and 2) we're talking current-standard converters here, or the bets are off. 

This is a nice confirmation of what most of us have agreed on long ago: there are greatly diminishing returns past a certain point.  What's bold here is placing that point where audio was set 25 years ago!  Great fun.

I'll still record 24bit whenever I can, to leave "sloppy" room, and surround sound is a different animal altogether.

I'm with you 100%, Peter.

He's not the only one...

Also present was a prat from the company which had supplied the recording equipment - he'd flown over from London to fix (again) the Tascam multitrack HDD recorder. Whilst we were trying to listen to the recording he kept blethering on about how obviously inferior the 16-bit CD was to his 24-bit recording, and couldn't we hear the 'graininess' in the sound from the CD.

I've heard the odd horror story about the Tascam multitrackers as well - rather overpriced and overhyped - especially compared to the Alesis, that just keeps on going, is easy to use and sounds at least as good most of the time, and a lot better when the Tascams aren't working!

I'm well pleased with the HD24XR - best multitrack machine I've ever bought.

Occasionally we compare and contrast the results we've got, and there are inevitably significant differences - but those differences plainly arise from different mic techniques, different mics, different halls, different post-pro methods and tastes, etc etc.   

When you consider just the mics and the halls, the differences will completely outweigh any fractional differences in performance, even between only moderately competent equipment.

I have, on one occasion, been very naughty. I've played back a recording from a CD, where I have processed the HF from about 7kHz upwards to have a very slight upward tilt - it's got to no more than about 3 or 4dB @ 20kHz,  to somebody (who couldn't see what I was doing) in direct comparison to the original material, played from the Alesis - so that's 24bit 44.1k. It won't take a genius to work out which one the punter swore blind was a 96k recording, would it?

I have a few mics that will produce output above 20kHz when provoked by trumpets, etc. and on the occasions that I've recorded the output for any reason, I've always rolled them off above about 18kHz, probably got cleaner recordings, and never heard a word of complaint from anybody about the result.

The other reasons for rolling off everything above 20kHz, even if you are recording at 96k (which I don't, except for experiments) are primarily two-fold. I'd roll it all off anyway, just to stick a finger up to all these people who insist that it's necessary, although none of them can actually tell whether it's present or not... and the more practical reason, when doing the experiments, was ultimately because of the one creature who can hear it - and doesn't like it - and that's the cat. Oh yes, I can reproduce content very comfortably up to 35kHz or so; that's where the Adam P11 ribbon tweeters start to roll off. And if you play anything like that through the system, with all of the LF removed, he gets pretty cross. Everybody thinks that dogs are the creatures with the extended hearing response - but cats can hear a lot higher up than any dog can.

This discussion reminded me that we have a (supposed) pest control device which emits ultrasonic audio, and which makes a handy test of the upper reaches of audio reproduction.  I've just heaved it out from the back of a cupboard and plugged it in, and recorded it from about a foot away with the little Zoom H2 running at 96kHz, 16 bits.

Looking at the result in Audition. one can see the result in the Frequency Analysis display very clearly.  With the noise floor knocking around -108dB, there's a sudden increase in level at 35kHz up to -72dB, which disappears back into the noise floor at about 45kHz.  The spectral display shows that the ultrasonic device emits a sweep between those frequencies with a period of about 1.3 seconds, and in fact it probably goes up to much higher frequencies still, judging by the shape of it.

Needless to say I can't hear it.  Nor can the dogs (they seem unconcerned when the device is turned on).  Attempting to record it playing back on Tannoy 607 speakers results in nothing significant showing, apart from a curious spike at 45kHz which I suspect is coming from something else (what?!). 

Conclusion - the Zoom can, remarkably, make ultrasonic recordings, but it looks like my speakers can't reproduce them.  I guess I could create a test tone in Audition to see, via the Zoom, what they can do at the top end.

These days my hearing gives out at about 12kHz at best.

I did once work with a producer in her late 40's who registered very high frequencies as pain.  We had a squeak in a piano which for the life of me I could not hear, but she ripped off her headphones exclaiming "ouch"!  Slowing down the recording later on, indeed there was a squeak at about 18Khz which I could not hear, but she found most unpleasant.  It would have been interesting to have had her on the SACD investigation listening panel.  If anyone could have heard the SACD difference it would have been her.

A little more on topic - see http://www.bostonaudiosociety.org/explanation.htm for details of the actual test gear and locations.  Apparently people in other forums are doing their best to rubbish this study on the ground that "other people using other test setups would be able to tell the difference" but I don't think they've realised the comprehensiveness nor the high standard of the test.

If anyone could have heard the SACD difference it would have been her.

When a student, Michael Gerzon had a measured response up to 23kHz.  I have heard, curiously, that an extended response is somewhat more common in severe asthmatics, as he was.  With a few people like that around, it is not surprising that the best previous study I know of indicated that 44.1kHz and 48kHz could sometimes be distinguished, but not any higher sampling rates.

Paul

When a student, Michael Gerzon had a measured response up to 23kHz.  I have heard, curiously, that an extended response is somewhat more common in severe asthmatics, as he was.  With a few people like that around, it is not surprising that the best previous study I know of indicated that 44.1kHz and 48kHz could sometimes be distinguished, but not any higher sampling rates.

The problem with all of those tests is that you are never sure exactly what you are listening to, and there's a good chance that it's not the sample rate change per se  that causes the difference in what is percieved anyway. Even if the anti-aliasing filters are perfect (haha!), just running the same converter at a different rate will alter things like the monotonacity, and what happens on the leading edges of every step change, which will almost certainly make minute differences to the summed output - within  the audible range, never mind outside it. The real culprits, in earlier tests, were the anti-alias filters though - had a sound all of their own!

What I don't know though is whether anybody has repeated any of these tests seriously with modern over-sampled D-A systems, which behave far better than their predecessors. I suspect that even if the tests could be run without serious experimental problems, they could only be done with headphones to be in any way reliable. And where do you get enough sensible children to test this on? I find it very hard to believe that there would be very many adults at all who could reliably distinguish any difference.

It would be interesting to try this with Apogees - a lot of people think that their converters running at 16/44.1 sound better than some of the 24/96 kit around.

The link between asthma and hearing is interesting, and I have no idea what a causal mechanism might be. I was mildly (not severely) asthmatic for many years, and my measured hearing response held up pretty well into my 20's, at least - although it never extended to 23kHz, I'm pretty sure. Well, it might have done when I was about 3, I suppose, but nobody tested it then...

Funny - as I recall it the producer with the extended hearing ability that I mentioned early had an asthmatic tendency.  Interesting.  And many years ago I read that there was some connection between asthma and the tonal analysis of a mother's voice.  Kind of circular!

Heck, there's some unbelievable crap being posted in other forums concerning this paper.  One guy suggested that only people who had spend a long time acclimatising in a studio should have been included in the listening panel.  Or, presumably, be allowed to buy "high res" players.

Heck, there's some unbelievable crap being posted in other forums concerning this paper.

I've just seen this result attributed to "bias"!  Someone has no concept of what testing means, I think.

Paul

If anyone is interested enough to do a search, there was a thread not more that a few weeks ago on this paper on the Hydrogen Audio Forum
http://www.hydrogenaudio.org/forums/index.php?act=portal
that quoted a few relevant parts of the paper. Towards the end of the thread is a post from one of the paper’s authors and also some links to where he wrote pointed replies to various specific criticisms in some of the audiophile oriented forums.

This discussion reminded me that we have a (supposed) pest control device which emits ultrasonic audio, and which makes a handy test of the upper reaches of audio reproduction.  I've just heaved it out from the back of a cupboard and plugged it in, and recorded it from about a foot away with the little Zoom H2 running at 96kHz, 16 bits.
Needless to say I can't hear it.  Nor can the dogs (they seem unconcerned when the device is turned on).

We have a similar device. When I bought it I plugged it in and waited for the dog to doze. Then I turned it on. He lifted his head and looked around, then got up and quietly left the room.