1. A method comprising: determining a first spectrogram of an audio signal; defining a similarity matrix of the audio signal based on the first spectrogram and a transposed version of the first spectrogram; identifying two or more similar frames in the similarity matrix that are more similar to a designated frame than to one or more other frames in the similarity matrix; creating a repeating spectrogram model based on the two or more similar frames that are identified in the similarity matrix; deriving a mask based on the repeating spectrogram model and the first spectrogram of the audio signal, the mask representative of similarities between the repeating spectrogram model and the first spectrogram of the audio signal; and extracting a repeating structure from the audio signal by applying the mask to the audio signal.