Abstract: An apparatus for recognizing predetermined patterns comprises an input for signal data; a pattern matching stage including a plurality of stores, each storing a representation of a pattern to be recognized; a similarity measurer for producing, for each representation, a measure of the similarity between the signal data and that representation; and a classification stage for deciding from the similarity measures which, if any, of the patterns to which the representations correspond is present in the signal data, and for indicating the presence of any such pattern. The classification stage makes its determination based on all the similarity measures after having been trained using information relating to known patterns and the similarity measurer from the pattern matching stage produced by inputting known patterns.