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Resolving spatial sampling effects in parametric directional filtering

: Kallinger, M.; Bürger, M.; Thiergart, O.; Küch, F.; Mahne, D.


IEEE Signal Processing Society:
IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP 2011. Vol.1 : Prague, Czech Republic, 22 - 27 May 2011
Piscataway/NJ: IEEE, 2011
ISBN: 978-1-4577-0538-0 (Print)
ISBN: 978-1-4577-0539-7
ISBN: 978-1-4577-0537-3 (Online)
International Conference on Acoustics, Speech and Signal Processing (ICASSP) <36, 2011, Prague>
Fraunhofer IIS ()

Directional Audio Coding (DirAC) represents an efficient scheme to analyze and reproduce spatial sound; the coded stream consists of a single-channel audio signal and few parameters. Estimation of these parameters ideally relies on figure-of-eight microphones and one omnidirectional microphone. The figure-of-eight directivity can be efficiently approximated by first-order differential microphone arrays. However, due to spatial sampling, there are considerable deviations from the required directivity at high frequencies. These deviations lead to incorrect spatial parameter estimates; especially, the instantaneous direction-of-arrival (DOA) becomes biased and - beyond a certain aliasing frequency - ambiguous. Parameters like the DOA drive subsequent processing units, e. g., for spatial filtering. In this paper we propose a novel strategy to compensate bias and ambiguity not directly w. r. t. the DOA but the output parameters of a spatial filtering processing unit. Simulation results confirm the benefits of the novel method, which does not involve additional computational load at run-time.