Spherical harmonic rake receivers for dereverberation
Hamza A. Javed, Alastair H. Moore, Patrick A. Naylor · 2016
This paper presents the use of acoustic rake receivers for speech dereverberation applications. Formulated in the spherical harmonic domain, the proposed spatial filter designs exploit the multipath propagation of sound in an enclosure, by individually capturing early reflections and combining them with the direct path. In this work we investigate the effect that the choice of early reflections has on dereverberation performance, and demonstrate that a rake finger selection criterion based on reflection energies, rather than their order, results in higher levels of reverberation suppression. A perceptually motivated design is also proposed, in which rake fingers are weighted based on the energy of the spatial filter required to produce them. The weighting scheme is shown to minimise the amplification of the diffuse reverberant sound field, thereby improving design robustness. Experimental simulations validate the effectiveness of the proposed rake receivers in highly reverberant environments, when compared to the plane-wave decomposition beamformer.