An implementation of a technology is described herein for recognizing the content of digital signals. The technology determines one or more hash values for the original content of a digital signal. In one implementation described herein, content recognition facilitates identification of the original audio content and other audio content that is substantially perceptually same to the original content. In another implementation described herein, audio content recognition facilitates semantic categorization of such original content so that it may be grouped with other audio works in the same semantic category. This abstract itself is not intended to limit the scope of this patent. The scope of the present invention is pointed out in the appending claims.