Saturday, March 12, 2011

People's expense accounts depend on their unquantifiable skills!

In 1999 the Super Audio CD format was released - higher sampling rate and longer word-length than the venerable 44.1Khz/16-bit Red Book standard that traces it lineage back to the late seventies and the Sony F1 digital audio system.
I've spoken to audio engineers who have made a very good career out of there being a benefit in re-mastering recordings to this newer standard. Their contention is that the difference is "night and day" (please go back and read that post).
Anyway - in 2007 a couple of chaps from the AES did a double-blind test to see if audio professionals could tell the difference - it turns out they can do no better than random. Remember - that was audio engineers, dubbing mixers, and other people who know what to listen for in properly recorded audio. Mix Magazine did a very good write-up under the title of The Emperor's New Sampling Rate!

This all reminded me of a project I was involved in at Oasis TV in the late nineties where we were home-brewing an audio-FX server for the dubbing suites. At the time 9 gigabyte SCSI drives were £1,500 and so compression was implied! None of the dubbing mixers liked this idea and so I made up a CD of various recordings; spot-effects, different music styles, dry vocal recordings and finished mixed programme. The compression we were using was MP2 (so not as good as the now-ubiquitous MP3) at 128, 164, and 192 kBits per sec (as well as uncompressed).
Remember - these were the golden-ears listening on £10k matched amp/speaker combos. It turns out that somewhere between 164 and 192kBits per sec these guys dropped to about 50% accuracy in discerning the compressed audio from the original.
Actually I think it's a bit more complicated than what these two double-blind tests suggest; I store all my music at 192kbit MP3 encoded using LAME 3.9 - for 99% of my music I can't hear the difference. However;
  • On some passages (typ. splash cymbals and some acoustic guitar parts) I am aware of compression artefact's.
  • An old VT editor once told me (around fifteen years ago) that although he liked the look of (the then new) DV format he felt more tired after a day of editing DV footage compared to BetaSP - the differences aren't immediately clear but over time one is better (in some way?) than the other.

I do believe that you can only get to the truth of these things by statistical analysis - I place no faith in audio professionals who expect their view to be taken seriously without the numbers to back it up. Their salaries depend on them being able to 'hear' the differences - if they are there or not.

1 comment:

Tim said...

At the Brit Awards there was a mobile audio truck brought in for "sweetening".
Tim