signal input means for receiving an acoustic signal;

scale-note-power detection means for applying a fast Fourier transform to the received acoustic signal at predetermined frame intervals and for obtaining the power of each note in a scale at each frame interval from the obtained power spectrum;

tempo-candidate detection means for summing up, for all the notes in the scale, an incremental value of the power of each note in the scale at the predetermined frame intervals to obtain a total of the incremental values of the powers, indicating the degree of change of all the notes at each frame interval, and for obtaining an average beat interval from the total of the incremental values of the powers to detect tempo candidates;

meter input means for receiving meter input by a user;

tapping detection means for detecting tapping input by the user;

recording means for recording tapping intervals, the time when each tapping is performed, and a beat value of each tapping;

tapping-tempo calculation means for calculating moving averages of the tapping intervals to calculate a tempo;

fluctuation calculation means for calculating a fluctuation in tapping tempo for each of latest moving averages;

tapping-tempo output means for outputting, when the fluctuation falls in a predetermined range, the tapping tempo, the time when the last tapping was performed, and a beat value at that time;

tempo determination means for selecting a beat interval close in number to the tapping tempo output from the tapping-tempo output means, from among beat-interval candidates detected by the tempo-candidate detection means;

first-beat-position output means for outputting a first-beat position closest to the beat value of tapping obtained when the fluctuation calculation means determines that tapping fluctuation falls in the predetermined range;

beat-position determination means for determining, as the starting beat position, the position of the tapping obtained when the fluctuation calculation means determines that tapping fluctuation falls in the predetermined range, and for determining each beat position therebefore and thereafter according to the tempo determined by the tempo determination means; and

bar detection means for detecting a bar-line position according to the first-beat position output from the first-beat-position output means and each beat position output from the beat-position determination means.