The icosahedral loudspeaker (IKO) as a compact spherical array is capable of 3rd order Ambisonics (TOA) beamforming, and it is used as a musical and technical instrument. To develop and verify beamforming with its 20 loudspeakers flush-mounted into the faces of the regular icosahedron, electroacoustic properties must be measured. We offer a collection of measurement data of IEM’s IKO1, IKO2, and IKO3 along with analysis tools to inspect these properties. Multiple-input-multiple-output (MIMO) data comprises: (i) laser vibrometry measurements of the 20x20 transfer functions from driving voltages to loudspeaker velocities, (ii) 20x16 finite impulse responses (FIR) of the TOA decoding filters, and (iii) 648x20 directional impulse responses from driving voltages to radiated sound pressure. With the open data sets, open source code, and resulting directivity patterns, we intend to support reproducible research about beamforming with spherical loudspeaker arrays.
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