Parameter estimation in Directional Audio Coding using linear microphone arrays

Directional Audio Coding (DirAC) provides an efficient description of spatial sound in terms of few audio down mix signals and parametric side information, namely the Direction Of Arrival (DOA) and the diffuseness of the sound. Traditionally, the parameters are derived based on the active sound intensity vector which is often determined via 2D or 3D microphone grids. Adapting this estimation strategy to linear arrays, which are preferred in various applications due to form factor constraints, yields comparatively poor results. This paper proposes to replace the intensity based DOA estimation in DirAC by a specific estimation of signal parameters via rotational invariance techniques, namely ESPRIT. Moreover, a diffuseness estimator exploiting the correlation between the array sensors is presented. Experimental results show that the DirAC concept can be applied in practice also in conjunction with linear arrays.