Hi-Rez - Another Myth Exploded!

[firev1]

Quote:

 
You're referring to this
 
"In one brief test with two subjects we added 14 dB of gain to the reference level quoted and tested the two sources with no input signal, to see whether the noise level of the CD audio channel would prove audible. Although one of the subjects was uncertain of his ability to hear the noise, both achieved results of 10/10 in detecting the CD loop. (We have not yet determined the threshold of this effect. With gain of more than 14 dB above reference, detection of the CD chain?s higher noise floor was easy, with no uncertainty. Tests with other subjects bore this out.)"
 
I'm referring to this
 
"4 A NOTE ON HIGH-RESOLUTION RECORDINGS
Though our tests failed to substantiate the claimed advantages of high-resolution encoding for two-channel audio, one trend became obvious very quickly and held up throughout our testing: virtually all of the SACD and DVD-A recordings sounded better than most CDs? sometimes much better. Had we not ?degraded? the sound to CD quality and blind-tested for audible differences, we would have been tempted to ascribe this sonic superiority to the recording processes used to make them.
Plausible reasons for the remarkable sound quality of these recordings emerged in discussions with some of the engineers currently working on such projects. This portion of the business is a niche market in which the end users are preselected, both for their aural acuity and for their willingness to buy expensive equipment, set it up correctly, and listen carefully in a low-noise environment. Partly because these recordings have not captured a large portion of the consumer market for music, engineers and producers are being given the freedom to produce recordings that sound as good as they can make them, without having to compress or equalize the signal to suit lesser systems and casual listening conditions. These recordings seem to have been made with great care and manifest affection, by engineers trying to please themselves and their peers. They sound like it, label after label. High-resolution audio discs do not have the overwhelming majority of the program material crammed into the top 20 (or even 10) dB of the available dynamic range, as so many CDs today do."
 
 
 
 
There is no lack of a positive result - http://www.aes.org/e-lib/browse.cfm?elib=15398
 
If you'd like to replicate it ...
 
- Recording microphones (a pair of Sennheiser MKH 8020), FR of 10Hz-60kHz.
- Two stereo feeds from the mic preamp (Millennia HV-3D) to two Micstasy ADCs, one set to 44.1/24 the other to 88.2/24
- Test signals: five musical/instrumental (orchestra, classical guitar, cymbals , voice, violin) recordings from live performances, taking place in several halls/rooms with varying dimensions & acoustics.
- For use in tests, 5-8 sec excerpts were used, with no processing except fade in.out via Pyramix 6 software.
- The 88.2 excerpts were downsampled to 44.1 via Pyramix software, so there were three sets of signals, native 44.1, native 88.2, and downsampled 88.2-->44.1.
 
- Playback: 5 blocks corresponding to the 5 excerpts, 12 trials per block ( i.e. all pairwise combinations of the three versions, each presented 4 times, twice in each of the two presentation orders), randomized ABX protocol.
- Playback hardware was an RME Fireface 800 DAC, a Grace m906 monitor controller, and a Classe CA-5200 stereo amp, feeding a pair of B&W 802D loudspeakers (FR 70Hz-33kHz).
- To avoid clipping a 750ms switching interval was employed, set in the user interface which was Cycle '74's Max/MSP/Jitter software package, all playback was at 24 bits.
 
 
Note:  In my personal opinion, I think the 750ms interval is good.  I think rapid or immediate time aligned switching in ABX could cause an illusion that two sounds are the same.
 
This test used very well controlled recordings completely under their own jurisdiction (unlike other tests selecting titles randomly, without knowing the recording technique involved).
 
 
 
 
High-rez isn't necessarily about hearing above 22.05kHz.  If that were the case, I'd suspect an extremely limited number of people could perhaps hear information in the 22.05~26.00kHz range, with a very subtle difference in overtones and such, however it that were the case I'd declare it as a useless format.
 
Clearly, recording at 1Hz~100kHz is truer to reality, especially if it removes the need for all kinds of filters.
 
When you start discussing the various side-effects and designs of these filters, whether the extended frequency range is actually perceivable or not, and discuss the hardware limitations or performance of various ADC / DAC chips or if your speakers have IMD, it starts to become very academic.  You could ill-quote different spec sheets all night, it just depends on the scenario of the situation, and the same rule applies to all listening tests looking for transparency, they are limited to the equipment in the scenario and human perceptivity.
 
 
Just to OT for a moment, Lavry says about 192kHz " the negative consequences of the reduced oversampling ratio far outweigh any benefits derived from the higher sample rates."
 
Really?  My DAC states "...[size=x-small]this DAC has up to 10 times less out-of-band noise compared to anything similar on the market today.  It also has the capability to accept a 216KHz sample rate while keeping the same digital filter oversampling rate and the same speed of the modulator."[/size]
 
It all seems situational to me.
 
My current DAC costs less than $200 and SACD's are pretty cheap, with lamented higher sound quality, so I don't see how the marketing side is an issue either, DSD/.DSF playback will come down in price eventually.
 
The marketing to watch out for is fake high-rez and fake DSD.  You can do this with a program like http://spectro.enpts.com/, but as high-rez content becomes more popular the content above 22kHz could be fabricated as well.
 
All in all microphones, speakers and the music itself is 6000 times more important than this sector, but I really fail to see the issue in trying to improve every component in audio playback to it's highest potential or slightly beyond.
 
For musical enjoyment I'll keep listening to 92 kbps MP3 with $10 Sony earbuds, but for the curiosity and intimacy of audio playback I'm very happy to try DSD and headphones with an FR like this... whyever not?
 

 
On the 750ms switch, this is to prevent audio illusions rather than introduce them, small differences are a lot more "visible" with quick change because our brains, with time, disposes audio memory and inserts its own perception of the audio into our hearing. Harmon studies have shown that quick change blind testing with trained listeners are a lot better than long term testing. 
 
On 192khz, I don't think our ears are really trained/tuned for ultrasonics http://people.xiph.org/~xiphmont/demo/neil-young.html
 
On high resolution mics with extended HF range, obviously recording with such mics have a sure benifit which is off course, transient response but to me, thats about it.
 
But anyway, high rez whether fake or real, the mastering of such recordings are very well taken care of, the few SACDs I own have better mastering than their CD originals.

 

[kiteki]

 
On the 750ms switch, this is to prevent audio illusions rather than introduce them, small differences are a lot more "visible" with quick change because our brains, with time, disposes audio memory and inserts its own perception of the audio into our hearing. Harmon studies have shown that quick change blind testing with trained listeners are a lot better than long term testing.

 
I'm not sure about that, I think it depends on what the comparison is.  I think very quick switching will make very minor changes in FR or volume easier to detect, yes, but perhaps not other sounds.  Our mind does actively delete sonic information too, it "organizes" it for faster processing, in linguistics or deleting room acoustics for example.  When the track is time aligned and the switch is instantaneous in 0.01 seconds, the mind might want to "organize" it in the same way we delete room acoustics, see this post - http://www.head-fi.org/t/510526/how-does-fidelity-relate-to-musical-enjoyment#post_6904141
 
 

 
On 192khz, I don't think our ears are really trained/tuned for ultrasonics http://people.xiph.org/~xiphmont/demo/neil-young.html

 
If it's present in real life, then I think over the last few million years we're more used to 1Hz~100kHz rather than the 20~20khz slice of cake, (if you want the recording to be as close to real life as possible).
 
That link in the "listening tests" section holds up the M&M study as empirical evidence, which I covered in my last two posts, and only cites one other study.

 

[firev1]

Quote:

 
I'm not sure about that, I think it depends on what the comparison is.  I think very quick switching will make very minor changes in FR or volume easier to detect, yes, but perhaps not other sounds.  Our mind does actively delete sonic information too, it "organizes" it for faster processing, in linguistics or deleting room acoustics for example.  When the track is time aligned and the switch is instantaneous in 0.01 seconds, the mind might want to "organize" it in the same way we delete room acoustics, see this post - http://www.head-fi.org/t/510526/how-does-fidelity-relate-to-musical-enjoyment#post_6904141
 
 
 
If it's present in real life, then I think over the last few million years we're more used to 1Hz~100kHz rather than the 20~20khz slice of cake, (if you want the recording to be as close to real life as possible).
 
That link in the "listening tests" section holds up the M&M study as empirical evidence, which I covered in my last two posts, and only cites one other study.

Pseudo science at work, I do agree with that post by Pio2001(I read it before), I never believed we are ever there yet or ever will be unless with have walls of mics or something along with a new format that supports 1000+ch surround sound. However psychoacoustic studies has indeed shown that short term, fast track switch sessions are preferred to long term sessions. Its like brain burn-in of new headphones, it changes your "neutral" perception and gives you wrong a judgement. I remembered once a test where some receivers were purposely modified for 1% THD in RMA and given back to their owners(the owners I believe were without the receiver for quite a long time) and they couldn't tell a difference. They were then given back their receivers properly soon afterwards but some of the owners claimed that the repaired receiver sounded "wrong". This test demonstrates the flaws of long term listening test. 
 
Personally, I believe we can perceive the 1-19Hz range, but that is because of visceral impact than auditory information. However above our hearing range of 20-22Hz, there is really little in the ultrasonics to hear and I don't believe that any of today's equipment is capable of even playing it back decently(lack of amplifiers with good specs AND extended ultrasonic range(increased IMD))  even in the case we do hear it. 
 
Even say if we can perceive ultrasonics for location images(like bats), I can't imagine how a mastering engineer is supposed to work with ultrasonics reliably given the inconsistencies in room acoustics of the listeners.
 
Oh, and sorry if the last paragraph is unrelated.
 
Also your theory of evolution is flawed, through the "millions" of years of human history, we have lost body hair, mass, strength and a bunch of other good stuff as well but also gaining more intelligence, you ask why, it is because we have no need to echolocate or hunt. If anything, I say our auditory senses may have well decreased over time because of the lack of need to use them to hunt. The human body only gives us information we need to know and I think it thinks that we have no need for ultrasonics unlike bats. 

 

[nick_charles]

Quote:

 
 
There is no lack of a positive result - http://www.aes.org/e-lib/browse.cfm?elib=15398
 

 
Ah, the Pras and Guastavino paper. Have you read the whole paper ? It is an interesting paper and hints at audible differences but there are a few methodological questions raised about it and their selection of data (possible cherry picking)  and statistical methods.
 
There is a thread about it on hydrogenaudio
 
http://www.hydrogenaudio.org/forums/index.php?showtopic=82264
 
I would hesitate to rush into using this paper as close the book proof positive - some of the results seem contradictory - nevertheless it is worth the $5 to buy it if you are an AES member. As a general rule it is unwise to cite studies where only the abstract is avavilable, authors (self included) tend not to mention possible study limitations or statistical legerdemain until the end of a paper

 
Seeing the raw data is always a good idea if at all possible.

 

[anetode]

If it's present in real life, then I think over the last few million years we're more used to 1Hz~100kHz rather than the 20~20khz slice of cake, (if you want the recording to be as close to real life as possible).

Before setting up a hopeful premise and looking for bits of supporting data you need to consider the basics.

Over the last few million years we have been exposed to, for instance, the entire electromagnetic spectrum; that doesn't mean that colorspace needs to include infared and ultraviolet to somehow improve the fidelity of the small band of information decipherable by human rods/cones. Likewise, though in a wholly different sense, the hair cells in the human cochlea have a range of sensitivity and simply don't respond to 1hz and 100khz frequencies of *any* SPL (at least any SPL they would ever survive). Bone conduction provides for an alternate stimulus which interacts with portions of the brain responsible for perception, however at high frequencies this is negligible due to the short wavelengths and the attendant limited penetration of human tissue.

 

[mnarwold]

Thanks for the awesome post. I love when science can trump hype!