A World Built of Sound

Mark Bocko

https://rochester.zoom.us/s/92474082834 Passcode: 066310

We are immersed in sound, and much of how we experience and navigate our environment is closely tied to our perception of sounds in space.  From where are the sounds coming? Are the sources of sound spatially concentrated or extended? How far away are they? And what is the size and geometry of the space in which one is immersed? Attempts to recreate spatial soundscapes date back at least 140 years, and today, multichannel audio is a highly developed field, from simple stereo reproduction a laptop computer, to sophisticated AR/VR headsets and 64 channel Dolby Atmos theaters. However, the development of spatial sound reproduction systems remains guided largely by subjective evaluation. “How did that sound to you?”

 In our lab at Rochester we are attempting to make the evaluation and design of spatial sound reproduction systems a more quantitative science and a more deterministic engineering activity. We have developed an analysis framework to predict listener descriptions of artificially reproduced spatial auditory scenes (the locations, extents, and distances to the acoustic sources and the nature of the space). Central to our framework are quantitative models of human binaural processing. There is a huge body of work on human spatial sound perception extending back to the time of Lord Rayleigh, but even today there remain many unanswered questions in human binaural sound processing. While we do not attempt to settle these long-standing questions, our framework incorporates the main features, processes, and timescales of human auditory system response. The framework’s predictions of listener perception of artificially rendered spatial auditory scenes agrees with the results reported by human listeners in tests conducted in our lab.

In parallel research in our lab we have been developing flat panel loudspeakers that may be integrated seamlessly into the built environment and in personal computing devices.  Attempts to build flat panel speakers go back nearly 100 years, and the results have been disappointing.  In work in our lab over the last 8-9 years we have identified and solved the key problems and we have demonstrated prototypes that in blind listening tests have been rated comparable in performance to highly rated prosumer grade loudspeakers.

The overarching goal of these activities is to create the technologies that will enable the development of built environments that invisibly and convincingly can transport people to any auditory world, either real or imagined.

 Mark F. Bocko joined the ECE Department in 1985.  His research has been in multiple areas of basic and applied science including early work on the quantum limits of force detection for gravitational wave detectors, the development of high-speed superconducting digital electronic circuits, and superconducting quantum computers.  He also has worked on low power CMOS integrated circuits for wireless vibration and acoustic sensors, high-dynamic-range, low-power CMOS image sensors, and non-contact ECG sensors. His current research focus is in the areas of electroacoustics and spatial sound. Bocko served as Chair of ECE from 2004-2010 and 2012-2020 and he founded the AME program in 2012. He has been the recipient of 5 University teaching awards and in 2008 he was named the Mercer Brugler Distinguished Teaching Professor.