Reducing Modal Error Propagation through Correcting Mismatched Microphone Gains Using Rapid

Microphone array calibration is required to accurately capture the information in an audio source recording. Existing calibration methods require expensive hardware and setup procedures to compute filters for correcting microphone responses. Typically, such methods struggle to extend measurement accuracy to low frequencies. As a result, the error due to microphone gain mismatch propagates to all the modes in the spherical harmonic domain representation of a signal. Several existing algorithms use modal representation of sound and error propagation in modes fundamentally limits the performance of such algorithms. A method for reducing the error propagation in modes by correcting the mismatched microphone gains is proposed, where RAndom PerturbatIons for Diffuse-field (RAPID) is used to design filters for correcting the mismatch. Experimental results show that the directivity pattern of a calibrated spherical microphone array using RAPID provides up to 6dB improvement in the front back factor.