A Method for Virtual Acoustic Auralisation in VR

Abstract

In today's industry, the use of prediction software in architectural acoustics is universal. Programs such as Odeon, CATT and CadnaA have become an integral part of the design process. These programs combine general acoustic theory with CAD modelling software to calculate the trajectory and intensity of sound waves as they travel around the room. By deciding upon positioning for sound sources for and listening positions, acousticians can track both the direction and level of a sound wave as it arrives at the listener. The basic theory then is that with this information we can map out a three-dimensional representation of how the source would sound to the listener before the room is built. This is known as virtual auralisation, creating a sonic map of a virtual room that is understandable to the listener because it mimics the acoustic standards of the real world. If the aim is to immerse the listener in the virtual world then the key is localisation. Allowing the listener to pinpoint which direction both the sound and its subsequent reflections are coming from is crucial to analysing the effect that acoustic design elements have on the overall sound. While surround sound could be looked to as an option, Odeon will also output to ambisonics b-format which can then be encoded for virtual reality. As a medium VR has been around for a while, however it is only recently with the release of relatively affordable platforms such as the HTC Vive and Oculus Rift that VR has gained mainstream appeal and with it, the support and infrastructure to encourage third party support for everything from games to VR experiences to virtual learning environments. In terms of acoustics, VR allows the listener to hear the sound source from any chosen position in the virtual space with full localisation and in three dimensions, effectively creating a fully realised, acoustically accurate virtual environment. One of the first companies to utilise this technology was the global architecture firm Arup. The SoundLab project is the most famous example of virtual auralisation for acoustic modelling and has become a benchmark for the industry and a showpiece for Arup. Though still utilising ambisonics, the SoundLab neglects to use VR headtracking and a binaural output. Instead opting to place the listener in the centre of an anechoic chamber with around twelve speakers surrounding them. While this is a far more expensive option, it does offer greatly increased sound quality. Through this project I will aim to apply the concept of Viral Auralisation through the medium of virtual reality to discuss the possibility of real time VR auralisation and its potential.