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Offline Martin Colloms  
#1 Posted : 11 June 2014 08:24:39(UTC)
Martin Colloms

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High Resolution : Capturing The Moment
London AES Meeting 10, 06, 2014
De Vere Rooms, High Holborn, London
By Bob Stewart and Peter Craven

With his formidable understanding of psychoacoustics Bob took the audience through a lightning review of more recent literature and discovery in psychoacoustics, in so doing illuminating how older listeners with some loss of high frequency sensitivity could still show high sensitivity to subtle sound quality differences. In fact he took the view that the last octave of audio, which does not carry much musical information anyway is typically severely compromised by the overall audio chain, source, studio and finally replay, notably by the long and inevitable cascade of low pass filters, and can at present play only a minor part in sound quality per se.
He showed with reference to psychoacoustic research from the last 10-15 years that traditional models of hearing needed adjustment in view of these later discoveries in auditory processing, for example showing that our discrimination of time is extraordinary, of the order of 10 microseconds implying an effective perception up to 100kHz even if for example steady state tones are inaudible above 12kHz at standard level. It’s to do with fast edges in sounds. As Bob noted our hearing is honed by millions of years of evolution for a rainforest ambience. To identify potential danger all around us, even in the dark, a twig breaking can be instantly assessed for location and distance in the forest ambience, and if animal generated, to some degree, how large the beast is. We are designed to spatially analyse transients, and this provided the basis in the talk for an exploration of how we should be encoding high resolution audio, and how Shannon and sampling theory, as currently applied may not be enough for true signal path transparency. The presentation led to a proposal for a high resolution audio practice which could offer higher sound quality while providing economies in data rates, transmission and storage.

Martin Colloms
Offline sandyk  
#2 Posted : 11 June 2014 10:20:32(UTC)

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Hi Martin
Much of this shouldn't be new to you, especially as this 75 year old with industrial type hearing damage (thanks to 44 years with Telstra,) and an Acoustic Neuroma pressing on the right ear canal, has been reporting hearing things that are impossible according to presently accepted hearing knowledge, and some of these findings have been confirmed by you previously.
I shouldn't be able to hear the difference between 320 MP3, 16/44.1 AAC (Youtube)Yuk ! 16/44.1 wav, 24/96 and even well recorded 24/192 from Barry Diament, but I can, and I have posted many times previously in C.A. and another forum that it's the rise time of the waveform that matters. Recording Engineer Jon P provided samples of 16/44.1 , 24/44.1 and 24/48 of the same recording in C.A. several months ago ,and I was only one of 2 people who posted their results. 24/48 seemed to just "come together", with 24/44.1 an improvement over 16/44.1
I shudder to think just how low my maximum sine wave hearing response would be these days.


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