Binaural transformation coding with simulated head tracking

The binaural transformation codec synthesizes generic binaural audio signals and generates accompanying side information. In the decoder the side information is used to personalize the generic signal. The performance of the basic codec is described in another paper; this paper describes the estimated effect on quality of incorporating limited head tracking. Generic HRTFs were used to spatialize two concurrent sound sources spatialized at ±30 or ±80 deg. The generic binaural signal was personalized in the BX decoder and at the same time the individual sound sources were rotated. These induced rotations are equivalent to compensating for head yaw rotations of −80, −40, −20, −10, and −5 deg, and for head pitch rotations of 22.5, 45, and 90 deg. Listening tests based on Recommendation ITU-R BS.1116-1 were used to evaluate the processed sounds. The tests were conducted using speech, vocals, guitars, and percussion source materials. It was found that the quality of the processed sound tended to degrade as the head yaw rotation increased. However, except for the head yaw condition −80 deg, the quality of the processed sound remained greater than 4.0 on the mean opinion scale. No deterioration of the processed sound was observed for the applied pitch rotations.