Categorical perception is the discontinuous categories of speech sounds. In speech perception, perceiving one sound at short voice onset times and another sound at longer voice onset times. The listener perceives only two (2) categories across the whole range of voice onset times. It is the perception of stimuli that vary along a physical continuum as belonging to discrete categories. Moreover, it is the inability to discriminate sounds within a phonemic category . Please see also Phoneme boundary effect.
List of books: Categorical,perception