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Description
Spatial aliasing in spherical microphone arrays (SMAs) arises from insufficient spatial sampling to capture high-order components, which are folded back into lower orders. This phenomenon is well understood: the frequency-independent spatial aliasing matrix characterises the mapping by which higher-order components are aliased into lower orders, as determined by the array’s sampling geometry. In addition, the mathematical expression of spatial aliasing also involves a frequency-dependent term determined by radial functions of different orders. This can be rigorously analysed by poles and zeros in the Laplace domain. Upon this, a closed-form expression for the corresponding time-domain spatial aliasing artefact is derived, which demonstrates that spatial aliasing introduces temporal spreading of higher-order Ambisonic signals measured with SMAs.