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.
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.