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AES conference London: High Resolution perception, paper about listening test
Kees de Visser
post Jul 5 2007, 11:25
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Unfortunately I wasn't able to visit the june 2007 AES Conference in London about High Resolution Audio.
The paper/presentation about a high-res audio listening test seems interesting. I'm wondering if anyone on HA happens to have been there and can share some information.

preview of the paper session:
Monday, June 25 11:00 – 12:30
Paper Session 2 — Perception

2-1 Which of the Two Digital Audio Systems Meets Best with the Analog System?— Wieslaw Woszczyk,1 Jan Engel,2 John Usher,1 Ronald Aarts,3 Derk Reefman3
1McGill University, Montreal, Quebec, Canada
2Centre for Quantitative Methods CQM BV
3Philips Research, Eindhoven, The Netherlands

In this listening test, two digital audio systems (B and C), and one analog system (A) were tested by 10 test persons who listened to a surround sound scene “live” (without recording). The main question to be answered was: “Which of the two digital systems meets best with the analog system?” Both digital versions had 24-bit dynamic resolution but differed in sampling rate with which the analog signal was sampled. One version © was sampled with a CD rate of 44.1 kHz, the other (B) 8 times faster. There were also two test conditions, where in one condition there was a bandwidth cut off at 20 kHz instead of the 100 kHz that was possible with special 100 kHz microphones and added super-tweeters. For each subject, the experiment was replicated six times, in each of the two conditions. The outcome of each experiment was a 0 or 1, where the 1 means that the, technically best, digital system B has been chosen as meeting the analog quality. The paper describes the test and the outcome.

Without having read the paper, it's not clear to me whether the test was double-blind or not. Apparently it was not possible to replay sources, since the audio source was "live". How reliable would a test like this be ?
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post Dec 24 2007, 10:38
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Man, this article has the worst abstract I have ever seen! I had to plough through the whole rag-tag thing just to figure out what exactly they had done! Still not sure if I understand it though...

As I can see it, its even worse than Pio2001 states: The 95% CI intervals between C1 and C2 overlap ironically @ 0,5, which make them equal. Thus no conclusions can be drawn (as stated at conclusion 4). I won't even comment on conclusion 5 laugh.gif.

The whole thing about the lowpassed high resolution version being perceived as better than the non-lowpassed high resolution is very interesting. Their hypothesis that ultrasound frequencies actually cause more artefacts seems to go against their recommendation of using a non-lowpassed high resolution for archiving!

Some more interesting bits of information from the article:

- This appreciation must relate to a number of perceived characteristics other than high-frequency response partly because microphones and loudspeakers normally used in studios do not have a substantially wider response than the audible range.

- In double-blind tests, casual and professional listeners could not reliably identify high-bandwidth and high-resolution (192 kHz 24bit versus 48 kHz 24bit) conditions.
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