Design and Limitations of Non-Coincidence Correction Filters for Soundfield Microphones

The tetrahedral microphone capsule arrangement in a Soundfield microphone captures a so-called A-format signal which is then converted to a corresponding B-format signal. The phase differences between the A-format signal channels due to non-coincidence of the microphone capsules cause errors in the corresponding B-format signals and linear combinations thereof. Various strategies for designing B-format non-coincidence correction filters are compared and limitations are discussed.