According to the present invention, a parameter adjustment section setting, in accordance with a first parameter indicating a variant factor for playback speed that is input, a second parameter and a third parameter, and a signal processing section adjusting at least one of playback speed and pitch of a sound of an audio signal based on the second parameter and the third parameter are provided, wherein the signal processing section adjusts the playback speed of the audio signal when the variant factor for playback speed that is input is less than a predetermined threshold and adjusts the playback speed and the pitch of a sound of the audio signal when the variant factor for playback speed that is input is above the predetermined threshold.