Point-of-View Binaural Audio Recording with High-Definition Video
Tech Info from Bob & Dan
Crosstalk Cancellation (CTC) is a means of converting binaural recordings for use in loudspeaker playback systems. In binaural recordings, the left and right channel signals are delivered via headphones to the listenersʼ respective left and right ears. When binaural signals are played back with a two-channel stereo loudspeaker system, the left channel can be heard as well in the right ear, and vice versa. This channel "bleed" or crosstalk between the ears severely diminishes localization accuracy. Our solution to this problem is to insert special signal processing prior to loudspeaker playback that will cancel the crosstalk between channels when the processed signals reach the listeners ears.
The development of CTC methods can be traced to the work of Atal, et al. at Bell Labs in the 1960's [U.S. Patent 3,236,949]. Cooper and Bauck later updated this process [JAES, 1989] with a computationally efficient IIR filter design suitable for real-time playback. Kirkeby et al. [IEEE, 1998] derived practical methods for implementing mathematically ideal solutions. In the 21st century, various researchers have extended these results to expand the listening sweet spot (e.g., see [Bai and Lee, JASA, 2006]) and improve the tonal balance (e.g., see Choueiri, self published).
Here at ImmersAV Technology, our CTC filters are based on the Kirkeby design and include proprietary enhancements to optimize tonal balance in consideration for various playback configurations. Since ImmersAV Technology specializes in making high performance binaural recordings, we have been able to use these recordings as reference for refining
our CTC filters, as we strive to match headphone and loudspeaker playback performances.
References: Atal, B.S., Hill, M., and Schroeder, M.R., "Apparent Sound Source Translator," U.S. Patent 3,236,949, Feb. 22, 1966) Cooper, D.H.,and Bauck, J., "Prospects for Transaural Recording," JAES Vol. 37, pp. 3-19, Feb. 1989 Kirkeby, O., Nelson, P.A., Hamada, H., and Bustamante, F.O., "Fast Deconvolution of Multichannel Systems using Regularization, IEEE Tans. Speech Audio Process., Vol. 6, pp. 189-194 (1998). Bai. M.R., and Lee, C.C., "Objective and subjective analysis of effects of listening angle on crosstalk cancellation in spatial sound reproduction," JASA, Vol. 120, pp. 1976-1989 (Oct. 2006). Choueiri, E.Y., "Optimal Crosstalk Cancellation for Binaural Audio with Two Loudspeakers," www.princeton.edu/3D3A/Publications/BACCHPaperV4d.pdf
