Abstract: An audio signal processing apparatus that processes a bit stream generated by coding an audio signal on a frame-by-frame basis, the bit stream including, for each frame, coded data representing the audio signal, additional data and attribute information, the audio signal processing apparatus including a decoding unit configured to decode the coded data to generate a decoded signal, a processing unit configured to process the decoded signal, a detection unit configured to detect whether or not there has been a change in the attribute information, and a storage unit, wherein the processing unit is configured to, when the change is not detected, process the decoded signal by using at least two pieces of additional data stored, and when the change is detected, process the decoded signal by using only either additional data before detection of the change or additional data after detection of the change.