One eighth of a sphere microphone array

International audienceSpherical microphone arrays are widespread nowadays, especially with the advent of techniques for decomposing acoustic fields on the basis of spherical harmonics (i.e. Ambisonics). However, in these approaches, the corresponding arrays require a quadratically increasing number of microphones as the order of the components to be estimated increases. However, for most applications, it is unnecessary to represent the whole solid angle of the sound field from the array point of view: for instance as soon as the array is placed near the boundaries of the acoustic field of study (i.e. walls in a room). To tackle this issue, one proposes a geometry which uses the acoustic reflections at room walls to decrease the number of required microphones. With one eight of a sphere array placed in the corner of a room, it is shown that only certain spherical harmonics are required for the expansion, and that the microphone number can drop up to 8 times lower when compared to the full spherical array configuration. However, for spherical beamforming approaches, it is shown that compromise between the order of decomposition and the beam width has to be made