[rdale]

"When the CD was designed, 44kHz at 16bits was chosen because that exceeds the limitations of human hearing."

No it wasn't, it was designed to be implementable given the technology of the time. Philips thought they were working on a 14 bit system, until Sony changed the spec to be 16 bits. That wasn't because Sony changed their minds about 'the limits of human hearing', it was because they thought they could implement the technology. 30 years later we can implement a bit depth of 24 bits with no problems.

According to the Wikipedia article on the history of the Compact Disc (http://en.wikipedia.org/wiki/Compact_Disc) the sampling rate was defined for the following reason:

"the exact sampling rate of 44.1 kHz was inherited from a method of converting digital audio into an analog video signal for storage on U-matic video tape, which was the most affordable way to transfer data from the recording studio to the CD manufacturer at the time the CD specification was being developed."

So again this has absolutely nothing to do with 'the limits of human hearing'.

Recording engineers, such as Barry Diament of Soundkeeper Recordings, think that the sound of 24/192 digital matches the output of the live microphone input of their recording desk. Barry Diament doesn't think 16/44.1 is nearly as good.

If you buy a recording at a high resolution you can always encode it as an MP3 or ACC so that it fits on your portable player. On the other hand if you buy an MP3 or AAC recording you can't bring back the lost resolution. So if I can fit my entire CD collection onto a cheap 1 TB hard drive, why do we care about how much disk space high resolution 24/96 or 24/192 audio will take up? When you don't have physical media it is trivial for a site to offer a range of resolutions according to the needs of the buyer. If I want 24/96 and someone else is only interested in 128 kps MP3s, then we can both download from the same site and only pay for the quality we need.

[Someone]

"the exact sampling rate of 44.1 kHz was inherited from a method of converting digital audio into an analog video signal for storage on U-matic video tape, which was the most affordable way to transfer data from the recording studio to the CD manufacturer at the time the CD specification was being developed."

So again this has absolutely nothing to do with 'the limits of human hearing'.

That is fairly selective quoting. A few linea up, that wikipedia article states:

The selection of the sample rate was based primarily on the need to reproduce the audible frequency range of 20 Hz - 20 kHz.

So, 44100 Hz is both 'around 40kHz' and 'a fixed number of samples per PAL scan line'. That is similar to how the first Mac got 22kHz sampling (http://www.folklore.org/StoryView.py?project=Macintosh&s...)

[ugh]

If people can’t hear the difference in blind tests all that talk about the supposedly better sound is utterly irrelevant.

[rdale]

Why would you value a 'blind test' over what an expert recording engineer, such as Barry Diament, thinks?

There are a lot of problems with blind tests, and there has certainly been much discussion about the arguments and counter arguments.

If you wheel in a bunch of untrained listeners off the street and get them to listen to recordings they are not familiar with, using a Hi-Fi that they are not familiar with, in stressful un-relaxed circumstances. Why would you expect to get some kind of definitive answer about 16/44.1 vs 24/192 for instance, that somehow trumps the opinion of highly regarded recording engineers?

[ugh]

Evidence trumps authority. I thought that was a basic lesson of science education?

[rdale]

I thought I listed some of the possible flaws in blind tests - there is nothing unscientific about that.

If you value the results of any sort of blind test, no matter how badly conducted, over the opinions of recording engineers, then it doesn't seem to be a purely scientific matter to me.

[ugh]

Your methodological criticisms are sound, it‘s just that they don’t seem to apply to the quoted paper (I found the PDF): http://www.mesoscale.nl/aes_article.pdf

[rdale]

OK, thanks I've read the paper.

If we are talking about whether 16 bits is sufficient dynamic range (the main subject of this Hacker News discussion) they say:

"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.)"

To me, this confirms that a bit depth of 16 is insufficient for high dynamic range music such as classical orchestral music. Maybe we don't need more than 20 bits (or about 16 bits plus 14 dB), but as we have the disk space, internet bandwidth and electronics to comfortably handle 24 bits I don't see the problem.

As far as sampling rate is concerned, they aren't comparing 24/192 PCM with 16/44.1 and so it isn't really relevant to a discussion about whether it is possible to hear the difference between these two formats using a current state of the art DAC.

I've no idea about the pros and cons of convertings SACD to 16/44.1 and doing a comparison as I don't personally care about SACD and don't think it has a future in downloadable non-physical formats.

They only talk vaguely about the actual equipment used which isn't normal for a Hi-Fi review. They say they inserted a comparator:

"always in the 16/44.1 signal path. Audio switching was handled by an ABX CS-5 double-blind comparator"

Have they done a double blind test to ensure that the effects of the comparator were inaudible?

They don't say what DAC or CD player they were using:

"For the CD loop we used a well-regarded professional CD recorder with real-time monitoring."

I don't have enough to go on here. Certainly DAC and CD players have improved a great deal in the last five years since these tests were made. From the description I can't tell whether of not the CD player and its DAC were state of the art five years ago.

So overall I agree the paper is an interesting read, but hardly the last word in answering the question of whether we should move to 24 bit recordings, or whether a sampling rate of 44.1 KHz is sufficient.

[bodyfour]

> Why would you value a 'blind test' over what an expert recording engineer, such as Barry Diament, thinks?

Because one is the scientific method, and the other is just an opinion?

[Nick_C]

I remember it was sold to the world as being because it exceeded human hearing. I remember it very clearly because I was into high-end hi-fi at the time and didn't believe it.