In this talk, we discuss the use of spherical harmonics as a tool to process spatial soundfields in a wide range of applications. Spherical harmonics are a set of orthogonal spatial basis functions that are capable of decomposing any arbitrary function defined on the sphere. In acoustics, when the soundfield is spatially sampled, spherical harmonics can be extensively used to achieve effective solutions to a wide range of applications. Our research group has worked on this area about two decades, and in this presentation, we aim to deliver a brief overview on a variety of applications and the respective spherical harmonics based solutions. These applications include spatial sound recording and reproduction, higher order microphone and higher order loudspeaker design, room modelling, room characterisation (DRR etc.), spatial noise cancellation (ANC over space), and HRTF related work.
Bio 1: Prof. Thushara D. Abhayapala leads the Audio & Acoustics group in the Research School of Engineering at the Australian National University. He received the B.E. degree (with First Class Honours) in Engineering in 1994 and the Ph.D. degree in Telecommunications Engineering in 1999, both from the Australian National University (ANU), Canberra. His research interests are in the areas of spatial audio and acoustic signal processing, multi-channel signal processing and spatial aspects of wireless communications. Among many contributions, he is the first to show how to use spherical harmonic decomposition in acoustic signal processing problems; the first researcher in the world to use harmonic based eigen decomposition to propose the concept of spherical microphone array; novel contributions on the multi-zone problem (multiple sound fields in the vicinity of each other); and was one of the first to show the fundamental limits of spatial sound field reproduction using arrays of loudspeakers. He worked in the industry for two years before his doctoral study, had consultancies with industry, and has active collaboration with Dolby and Sony research labs in Japan. He has supervised over 30 PhD students and coauthored over 230 peer reviewed papers. Professor Abhayapala is an Associate Editor of IEEE/ACM Transactions on Audio, Speech, and Language Processing. He is a Member of the Audio and Acoustic Signal Processing Technical Committee (2011?-2016) of the IEEE Signal Processing Society. He is a Fellow of the Engineers Australia (IEAust). He is currently the Deputy Dean of the College of Engineering and Computer Science, ANU. He was the the Director of the Research School of Engineering, ANU from January 2010 to October 2014 and the Leader of the Wireless Signal Processing Program at the National ICT Australia from November 2005 to June 2007.
Bio 2: Dr Prasanga N. Samarasinghe is a Research Fellow in the Audio & Acoustics group in the Research School of Engineering at the Australian National University. She received her B.E. degree (with first-class honors) in electronic and electrical engineering from the University of Peradeniya, Sri Lanka, in 2009. She completed her Ph.D. degree at the Australian National University (ANU), Canberra in 2014 including a 5 months long Research Engineer Internship at Dolby Laboratories - Australia. Her research interests include spatial audio, room acoustics, active noise control, and multi-channel signal processing.