A reproduction apparatus 2 collects sounds on which spread codes are superimposed with a microphone 20 to calculate correlation values between the collected sound signals and the same spread codes as those of an apparatus which performed the superimposition to identify content reproduced by a reproduction apparatus 1 in accordance with the intensity of the peaks of the calculated correlation values. A control portion 22 identifies content which is correlated with the identified content and is necessary for the reproduction apparatus 2. The control portion 22 reads out the identified content data from a content data storage portion 25 to output the musical score data and the audio data to a display portion 23 and a reproduction portion 26, respectively. The display portion 23 displays the input musical score data on a screen, while the reproduction portion 26 reproduces the input audio data to generate sound signals.