A system and method for calibrating mismatch between the transmit and receive filters of communication nodes in MIMO communications systems. The exemplary calibration algorithm involves two nodes communicating back-and-forth and, based on the received signal, the receiving node calculating an updated calibration matrix and calculating parameters for communicating over the best singular mode (BSM). According to a salient aspect, the updated calibration matrix and the BSM parameters can be calculated as a function of a difference between previous estimates thereof and the current received signal. The calculated BSM parameters and calibration matrix can then be used to transmit a signal back to the other node, which similarly performs the calibration matrix and BSM parameter calculation steps. The calibration algorithm can be repeated by the nodes a suitable number of iterations for each nodes' respective calibration matrix to impose reciprocity on the effective communication channel therebetween.

An audio processor (1) includes a first filter coefficient calculator (31) that calculates a first filter coefficient so as to correspond to first gains for respective bands set by a user, a second filter coefficient calculator (32) that if values of third gains for respective bands of the first filter coefficient are greater than an absolute value of a second gain set by the user, calculates a second filter coefficient by limiting the values of the third gains for the respective bands to the amplitude value of the second gain, and a filtering unit (35) that filters an audio signal that has been transformed into a frequency-domain signal, using the second filter coefficient.

An audio processor (1) includes a first filter coefficient calculator (31) that calculates a first filter coefficient so as to correspond to first gains for respective bands set by a user, a second filter coefficient calculator (32) that if values of third gains for respective bands of the first filter coefficient are greater than an absolute value of a second gain set by the user, calculates a second filter coefficient by limiting the values of the third gains for the respective bands to the amplitude value of the second gain, and a filtering unit (35) that filters an audio signal that has been transformed into a frequency-domain signal, using the second filter coefficient.