US Patent 10492018 Symmetric binaural rendering for high-order ambisonics

Techniques of performing binaural rendering involve combining left and right HRTFs from speakers symmetrically placed with respect to a forward axis of a listener's head. Because of the symmetry of the listening geometry, a decoded loudspeaker signal resulting from each speaker may be decomposed into symmetric and antisymmetric components according to whether a spherical harmonic associated with a respective ambisonic channel is symmetric or antisymmetric about the forward axis. The result involves rendering the left and right headphone speakers using the same sum and difference HRTFs rather than a different pair of HRFTs for each headphone speaker.