Patent ID: 8431810

Claim:
A tempo detection device comprising: a basic feature amount extracting section which extracts a plurality of types of basic feature amounts from an input audio signal; a weighting and adding section which weights and adds the basic feature amounts of the plurality of types extracted in the basic feature amount extracting section to obtain an addition signal; and a tempo detecting section which detects BPM indicating the tempo on the basis of a periodic component included in the addition signal obtained in the weighting and adding section, wherein the tempo detecting section includes: a fast Fourier transform section which performs a fast Fourier transform for the addition signal for each frame obtained in the weighting and adding section; a score calculating section which divides respective samples in a frequency axis output from the fast Fourier transform section into a predetermined number of continuous frequency regions, which include a frequency region in which it is assumed that a correct BPM is present, and in which a frequency region adjacent to a low pass side becomes one half and a frequency region adjacent to a high pass side becomes double, and calculates a score corresponding to the level of each sample data for each frequency region and for each sample; a score adding section which matches the numbers of samples of the respective frequency regions and adds the sample scores of the respective frequency regions for the corresponding samples, on the basis of the score for each frequency region and for each sample calculated in the score calculating section; and a BPM determining section which determines the BPM corresponding to a frequency in the frequency region, in which it is assumed that the correct BPM is present, corresponding to the samples having a maximum score addition value among score addition values for each of the samples obtained by the addition of the score adding section, as the BPM indicating the tempo.