Since the creation of the Institute of Sound Recording (IoSR) in 1998 it has become known internationally as a leading centre for research in psychoacoustic engineering, with world-class facilities and with significant funding from research councils (in particular EPSRC) and from industry (we have successfully completed projects in collaboration with Adrian James Acoustics, Bang & Olufsen, BBC R&D, Genelec, Harman-Becker, Institut für Rundfunktechnik, Meridian Audio, Nokia, Pharos Communications, Sony BPE and Wolfson Microelectronics/Cirrus Logic). Additionally, the IoSR was a founding partner in the EPSRC-funded Digital Music Research Network (DMRN
) and Spatial Audio Creative Engineering Network (SpACE-Net).
We are interested in human perception of audio quality, primarily of high-fidelity music signals. Overall perceived quality depends, at least in part, on perception of lower-level timbral and spatial attributes such as brightness, warmth, locatedness and envelopment. These attributes depend, in turn, on acoustic parameters such as frequency spectrum and inter-aural cross-correlation coefficient.
Using a combination of acoustic measurement and human listening tests we are exploring the connections between acoustic parameters and perceived timbral and spatial attributes, and also between these perceptual attributes and overall quality and listener preference. From our findings we are developing mathematical and computational models of human auditory perception, and engineering perceptually-motivated audio tools.
Our work combines elements of acoustics, digital signal processing, psychoacoustics (theoretical and experimental), psychology, sound synthesis, software engineering, statistical analysis and user-interface design, with an understanding of the aesthetics of sound and music.
Applications & Outputs
One particular focus of our work is the development of tools to predict the perceived audio quality of a given soundfield or audio signal. If, for example, a new concert hall, hi-fi or audio codec is being designed, it is important to know how each candidate prototype would be rated by human listeners and how it would compare to other products which may be in competition. Traditional acoustic and electronic measurements (e.g. RT60, SNR, THD) can give some indication but a truly representative assessment requires lengthy listening tests with a panel of skilled human listeners. Such tests are time-consuming, costly and often logistically difficult. The tools that we are developing will describe the quality of the prototype without the need for human listeners.
Similarly, to monitor the quality of broadcast audio, and perhaps make decisions about appropriate allocation of finite bandwidth; or to assess the quality of a recording as it is being made, and make appropriate adjustments to balance, microphones or processing; requires accurate monitoring in a good listening environment and the undivided attention of a skilled engineer. If the monitoring is poor, the listening environment is compromised, or the engineer is multi-tasking or tired, then our audio quality prediction tools may be invaluable.
Complementary strands of our work deal with the development of quality advisors, which can advise on the most appropriate recording or coding techniques in advance of the source audio being available; of perceptually-motivated signal processing systems, which allow direct control over the timbral and spatial attributes of sound; and of listener training systems, which can strengthen and maintain the skills of human listeners wanting, or required, to critically assess audio.
Our research aims to provide tools to assist in any area where assessment of the quality of audio as perceived by human listeners (either overall or in terms of specific timbral or spatial attributes) is desirable but, for one reason or another, potentially problematic; and to provide complementary tools to facilitate appropriate adjustment where the assessed quality is not as it should be. More succinctly, and more generally, we aim to engineer perceptually-motivated signal analysis, processing and control systems. If we have a single over-arching goal then it is simply this: to make sound better.