A dual-mode architecture for headphones delivering surround sound: Low-order IIR filter models approach

In this paper we propose a method for conventional headphones to reproduce 5.1 and 7.1-channel surround sounds that are increasingly used in music and movies. When converting multi-channel audio to stereo, we adopted shuffler filter structures and least-squares approximation of FIR (Finite Impulse Response) by IIR (Infinite Impulse Response) filters in order to lower the computational cost and memory usage. By taking advantage of shuffler filters, the architecture is easy to be extended, thus compatible with discrete 5.1 and 7.1-channel sources. The algorithm in the least-squares sense enables the designed low-order IIR filters to approach the long-length HRTFs (Head Related Transfer Functions) with small approximation errors. As a result, the proposed architecture achieves not merely low cost but high performance, allowing headphones to deliver similar surround sound as heard in home theatres.