Patent ID: 8660678

Claim:
A method for audio processing, comprising: receiving in an electronic processor an audio input from a performance of a musical piece having a score; defining a two-dimensional state space comprising coordinates modeling the performance, each coordinate X n corresponding to a respective location L n in the score at a time n and a tempo of the performance α n at time n; for each of a plurality of times i during the performance, defining a set of particles {X i ,W i } having respective coordinates X i =(L i ,α i ) in the two-dimensional state space and weights W i corresponding to respective probabilities of the coordinates; defining a Hidden Markov Model (HMM) having observable states corresponding to the audio input and hidden states corresponding to the location and the tempo, as specified by the particles; iteratively computing at the plurality of the times the respective weights W i of the particles in the two-dimensional state space based on the audio input; and matching the performance to the score by computing, at each of the times, a weighted sum over the particles using the respective weights W i in order to decode the HMM so as to find a current value of X n , which gives a most likely current location in the score and most likely current tempo.