Thursday 12th February

Session Chair:
Nicolas Tsingos, Dolby Laboratories, San Francisco, CA, USA

Paper Session 3: Spatial Audio

3-1: Building an OpenAL Implementation Using Ambisonics

Richard Furse, Blue Ripple Sound

OpenAL allows 3-D spatialization to be provided from outside game code; new implementations can be "plugged in". Ambisonics separates an abstract sound field representation from actual loudspeaker feeds and allows decoding to large number of loudspeakers, including arrangements in 3-D. We present the design of an Ambisonic OpenAL driver implemented in three segments: an "environment" managing state, a "renderer" using this state to generate an abstract Ambisonic sound field representation, and a "decoder" that applies whatever decoding algorithm is desired and feeds the available hardware. We also describe techniques to decode for surround stereo and headphones.

3-2: 3-D Sound for 3-D Games - Beyond 5.1

Simon Goodwin, Codemasters Software Company, UK

7.1, HDMI 1.3, and 3-D loudspeaker configurations could potentially improve game audio beyond the scope of 5.1 cinema surround, but there are practical issues including ergonomics, compatibility, and the lack of standard layouts. The paper explores possibilities and trade-offs and outlines a basis for standardization. It seeks to justify the need for collaboration across the game and audio industry so that consumers benefit, rather than just get more confused. While there are still details that need to be agreed, the paper illustrates a set of approaches that give high quality 3-D with equipment that is fast becoming the new consumer standard, while remaining closely compatible with existing CD and DVD mixes.

3-3: Binaural Reproduction Over Loudspeakers Using in-situ Measurements of Real Rooms: A Feasibility Study

Simeon Delikaris-Manias, Paul Gillieron Acoustic Design, London, UK; Timos Papadopoulos, Institute of Sound and Vibration Research (ISVR), Southampton, UK

Binaural reproduction over loudspeakers represents a very promising technique for PC and console gaming applications. Its performance could, however, significantly improve by the incorporation of in-situ plant measurement in its implementation. We present such in-situ plant measurement results for various real rooms, and we give a detailed analysis of the optimal choice of parameters for their inversion and of the expected improvements in the performance of the system.

3-4: Localization Quality Assessment in Source Separation-Based Up-Mixing Algorithms

Dan Barry, Dublin Institute of Technology, Dublin, Ireland; Gavin Kearney, Trinity College, Dublin, Ireland

In this paper we explore the source localization accuracy and perceived spatial distortion of a source separation-based up-mix algorithm. Unlike traditional up-mixing techniques, source separation based techniques allow individual sources to be separated from the mixture and repositioned independently within the surround sound field. Generally, spectral artifacts generated during the source separation process are masked when the up-mixed sound field is presented in its entirety; however, this can lead to spatial distortion and ambiguous source localization. Here, we use subjective testing to compare the localization perceived on a purposely generated 5.1 presentation and an up-mix (2.0 to 5.1) of the same source material using a source separation based up-mix algorithm.