An audio signal processing apparatus has a plurality of nodes which include a node in operation and a node on standby for redundancy. Both the node in operation and the node on standby execute the same signal processing on input same audio signals in accordance with supplied same control signals, respectively. Only the node in operation is permitted to output the frame in which the processed audio signals are contained, and the node on standby is prohibited from outputting the frame to the audio bus. In response to a switch instruction, in a sampling cycle, the node in operation turns to be on standby and the node on standby turns to be in operation.