An audio signal generating apparatus is provided which makes it possible to supply a new music entertainment that enables users to actively participate in performance of musical compositions based on audio data that is coded in a predetermined format from audio signals, and a program for implementing the method, and a storage medium storing the program. Motion information corresponding to a motion of a user is acquired. An audio signal is acquired from audio data coded from the audio signal according to the predetermined format, and processing is performed on the acquired audio signal according to acquired motion information.