A conduct-along system that can give expressions to sounds and/or images, in which expressions are added to sounds and/or images following the playback of sounds and/or images in real-time based on any one or any combination of parameters, such as tempo, intensity, beat timing and accent, detected from the movement of an input device. The conduct-along system detects any one or any combination of parameters, such as tempo, intensity, beat timing and accent, from the movements of the input device, and plays back voices and/or images in real-time following any one or any combination of detected parameters, such as tempo, intensity, beat timing and accent.