1. A recognition unit comprising: a signal input section for receiving a signal to be recognized; a quantizer for mapping an input data value inputted from said signal input section into a discrete value; and a path selecting section having at least one path input terminal which is connected to a path output terminal of another recognition unit and at least one path output terminal which is connected to a path input terminal of another recognition unit, said path selecting section making a connection between said path input terminal of said path selecting section and said path output terminal of said path selecting section according to an output of said quantizer.