Virtual microphones synthesized for this research: 
4th ORDER CARDIOIDS
130th AES Convention – London 13-16 May 2011
Matlab script
•Inputs:
ü2048 samples of each IR
üThe number of virtual microphones
üDirectivity of each virtual microphone
üAzimuth and elevation of each virtual microphone
IRs Matrix inversion
Output: FIR filters matrix
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With a Matlab script we can perform the matrix inversion…

We choose the 4th order cardioids because they are the right compromise for covering the sphere without overlaps of their directivity.