Efficient Conversion of X.Y Surround Sound Content to Binaural Head-Tracked Form for HRTF-Enabled Playback

Binaural presentation of X.Y sound is usually performed using virtual audio principles - that is, by attempting to virtually reproduce the setup of the X+Y loudspeakers in the reference room configuration. The computational cost of such playback is linear in the number of channels in the X.Y setup. We present a novel scheme that computes, offline, a spatio-temporal representation of the sound field in the listening area and store it as a multipole expansion. During head-tracked playback, the binaural signal is obtained by evaluating the multipole expansion at the ear position corresponding to the current user pose, resulting in a fixed playback cost. The representation is further extended to incorporate individualized HRTFs at no additional cost. Simulation results are presented.