An audio signal (172) representative of an acoustic signal is provided to an auditory model (105). The auditory model (105) produces a high-dimensional feature set based on physiological responses, as simulated by the auditory model (105), to the acoustic signal. A multidimensional analyzer (106) orthogonalizes and truncates the feature set based on contributions by components of the orthogonal set to a cortical representation of the acoustic signal. The truncated feature set is then provided to classifier (108), where a predetermined sound is discriminated from the acoustic signal.