1. A signal clustering apparatus comprising: a feature extraction unit configured to extract a feature having a distribution from a signal; a division unit configured to divide the feature into segments by a predetermined duration; a reference model acquisition unit configured to acquire a plurality of reference models, each reference model representing a specific feature having a distribution; a first feature vector calculation unit configured to calculate a first feature vector of each segment by comparing each segment with the plurality of reference models, the first feature vector having a plurality of elements corresponding to each reference model, a value of an element attenuating when a divided feature of the segment shifting from a center of the distribution of the specific feature of the reference model corresponding to the element; an inter-models similarity calculation unit configured to calculate a similarity between two reference models as all pairs selected from the plurality of reference models; a second feature vector calculation unit configured to calculate a second feature vector of each segment, the second feature vector having a plurality of elements corresponding to each reference model, a value of an element of the second feature being a weighted sum by multiplying each element of the first feature vector of the same segment by the similarity between each reference model and the reference model corresponding to the element; and a clustering unit configured to cluster segments corresponding to second feature vectors of which the plurality of elements are similar values to one class.