US Patent 9560441 Determining speaker direction using a spherical microphone array

A system that detects audio including speech using a spherical sensor array estimates a direction of arrival of the speech using a Kalman filter. To improve the estimates of the Kalman filter, the system estimates a noise covariance matrix, representing noise detected by the array. The structure of the noise covariance matrix is determined, using an assumption of spherically isotropic diffuse noise. The intensity of the noise covariance matrix is estimated based on the intensity of audio detected by the array.