Audio Engineering Society Convention Paper Presented at the 129th Convention 2010 November 4–7 San Francisco, CA, USA The papers at this Convention have been selected on the basis of a submitted abstract and extended precis that have been peer reviewed by at least two qualified anonymous reviewers. This convention paper has been reproduced from the author’s advance manuscript, without editing, corrections, or consideration by the Review Board. The AES takes no responsibility for the contents. Additional papers may be obtained by sending request and remittance to Audio Engineering Society, 60 East 42 nd Street, New York, New York 10165-2520, USA; also see www.aes.org. All rights reserved. Reproduction of this paper, or any portion thereof, is not permitted without direct permission from the Journal of the Audio Engineering Society. Inherent Doppler Properties of Spatial Audio Martin J. Morrell 1 , and Joshua D. Reiss 1 1 Queen Mary Universty of London, London, Mile End Road, E1 4PL, United Kingdom Correspondence should be addressed to Martin Morrell (martin.morrell@elec.qmul.ac.uk) ABSTRACT The Doppler shift is a naturally occurring phenomenon that shifts the pitch of sound if the emitting objects distance to the listener is not a constant. These pitch deviations, alongside amplitude change help humans to localise a sources position, velocity and movement direction. In this paper we investigate spatial audio reproduction methods to determine if Doppler shift is present for a moving sound source. We expand spatialisation techniques to include time-variance in order to produce the Doppler shift. Recordings of several different loudspeaker layouts demonstrate the presence of Doppler with and without time-variance, comparing this to the pre-calculated theoretical values. 1. INTRODUCTION There are various techniques for rendering spatial audio over loudspeakers. Most techniques are based on being able to localise the direction of the vir- tual audio source. In this paper we investigate if spatial audio techniques inherently include Doppler shift when virtual sources are moved. Ahrens [1] and DeVries [2] have both shown that Doppler is an inherent part of wave field synthesis. They have shown that the observed Doppler shift does not match the expected Doppler shift, with the error increasing as speed increases. Ahrens later ex- panded the theory to include retarded time which makes the expected and observed Doppler shift er- ror decrease. 2. DOPPLER THEORY It is well known that sound emitted from moving sources exhibit a frequency shift on the emitted sound, causing it to be heard higher in pitch when moving towards a listener and lower in pitch when it is moving away from a listener. The Doppler shift formula may be given as [3], ω l = ω s 1+ V ls c 1 − V sl c (1) where ω l and ω s are the listener and source fre- quency, v sl is the source to listener velocity, v ls is 8278