An information processing apparatus that stores a plurality of pieces of audio data, displays information corresponding to each of the plurality of pieces of audio data, receives an input selecting at least one of the plurality of pieces of audio data, reproduces a first piece of the plurality of pieces of audio data, and initiates simultaneous reproduction of a second piece of the plurality of pieces of audio data based on an input received at the interface, processes the first and second pieces of the audio data such that the first and second pieces of the audio data are separately audible by the user, and outputs the processed first and second pieces of the audio data.