**When:** Tuesday 4th October, 2016 @ 5:10 PM

**Where:** Room 4.31/4.33, Informatics Forum, University of Edinburgh

**Seminar Title**

*Auralising rooms from computer models: Seeking synergies between geometric and wave-based techniques*

**Seminar Speaker**

Dr. Jonathan Hargreaves (Acoustics Research Centre, University of Salford).

**Seminar Abstract**

Auralisation of a space requires measured or simulated data covering the full audible frequency spectrum. For numerical simulation this is extremely challenging, since that bandwidth covers many octaves in which the wavelength changes from being large with respect to features of the space to being comparatively much smaller. Hence the most efficient way of describing acoustic propagation changes from wave descriptions at low frequencies to geometric ray and sound-beam energy descriptions at high frequencies, and these differences are reflected in the disparate classes of algorithms that are applied. Geometric propagation assumptions yield efficient algorithms, but the maximum accuracy they can achieve is limited by how well the geometric assumption represents sound propagation in a given scenario; this comprises their accuracy at low frequencies in particular. Methods that directly model wave effects are more accurate but have a computational cost that scales with problem size and frequency, thereby limiting them to small or low frequency scenarios. Hence it is often necessary to operate two algorithms in parallel handling the different bandwidths. Due to their differing formulations however, combing the output data can be a rather arbitrary process.

This talk will attempt to address this disparity by examining synergies between the Boundary Element Method (BEM) and geometric approaches. Specifically, it will focus on how the use of appropriately chosen oscillatory basis functions in BEM can produce leading-order geometric behaviour at high frequencies. How this produces synergies that might ultimately lead to a single unified full-bandwidth algorithm for early-time will be discussed.

**Speaker Bio**

Jonathan was awarded an MEng in Engineering & Computing Science from the University of Oxford in 2000 and a PhD in Acoustic Engineering from the University of Salford in 2007, where he remains as a Lecturer in Acoustics, Audio and Broadcast Engineering. The title of his PhD thesis was “Time Domain Boundary Element Methods for Room Acoustics” and this remains influential in his current research areas. Jonathan has had the pleasure of being involved in a wide variety of public engagement activities, including a number of TV appearances, and is passionate about performing, engineering and enjoying live music. He was awarded the UK Institute of Acoustics’ Tyndall Medal in September 2016.