An information processing apparatus comprising: a storage unit configured to store a plurality of pieces of audio data; an interface configured to display information corresponding to each of the plurality of pieces of the audio data and receive an input selecting at least one of the plurality of pieces of the audio data, wherein the interface is a touch panel display configured to receive a touch input as the input selecting at least one of the plurality of pieces of the audio data; a reproduction unit configured to simultaneously reproduce the selected piece and a second piece of the audio data, the selected and second piece of the audio data being different from one another; a sound processing unit configured to process the selected piece and the second piece of the audio data simultaneously reproduced by the reproduction unit; an output unit configured to output the selected and second pieces of the audio data output from the sound processing unit; and a control unit configured to control the reproduction unit to reproduce the selected piece of the audio data, and initiate simultaneous reproduction of the second piece of the audio data based on a further input received at the interface, and control the sound processing unit to process the selected and second pieces of the audio data to be separately audible by the user, wherein the control unit is configured to control the reproduction unit to reproduce the selected piece of the audio data; characterised in that: the control unit is configured to initiate simultaneous reproduction of the second piece of the audio data based on a detection that a continuous touch input received at the touch panel display corresponding to the second piece of the audio data has exceeded a predetermined time period, and to control the reproduction unit to stop reproduction of the second piece of the audio data and continue reproduction of the selected piece of the audio data based on a detection that the continuous touch input received at the touch panel display has ended. a storage unit configured to store a plurality of pieces of audio data; an interface configured to display information corresponding to each of the plurality of pieces of the audio data and receive an input selecting at least one of the plurality of pieces of the audio data, wherein the interface is a touch panel display configured to receive a touch input as the input selecting at least one of the plurality of pieces of the audio data; a reproduction unit configured to simultaneously reproduce the selected piece and a second piece of the audio data, the selected and second piece of the audio data being different from one another; a sound processing unit configured to process the selected piece and the second piece of the audio data simultaneously reproduced by the reproduction unit; an output unit configured to output the selected and second pieces of the audio data output from the sound processing unit; and a control unit configured to control the reproduction unit to reproduce the selected piece of the audio data, and initiate simultaneous reproduction of the second piece of the audio data based on a further input received at the interface, and control the sound processing unit to process the selected and second pieces of the audio data to be separately audible by the user, wherein the control unit is configured to control the reproduction unit to reproduce the selected piece of the audio data; characterised in that: the control unit is configured to initiate simultaneous reproduction of the second piece of the audio data based on a detection that a continuous touch input received at the touch panel display corresponding to the second piece of the audio data has exceeded a predetermined time period, and to control the reproduction unit to stop reproduction of the second piece of the audio data and continue reproduction of the selected piece of the audio data based on a detection that the continuous touch input received at the touch panel display has ended. the control unit is configured to initiate simultaneous reproduction of the second piece of the audio data based on a detection that a continuous touch input received at the touch panel display corresponding to the second piece of the audio data has exceeded a predetermined time period, and to control the reproduction unit to stop reproduction of the second piece of the audio data and continue reproduction of the selected piece of the audio data based on a detection that the continuous touch input received at the touch panel display has ended.