Auditory perception and speech evolution.

Abstract

Human speech perception seems to involve the ability to recognize groupings of speech sounds rather than component phonemes, and to distinguish between permuted orders of items within sequences as holistic entities. Humans can use this Holistic Pattern Recognition (HPR) not only with speech and music, but also with sequences of arbitrarily selected sounds after very little practice. Infrahuman primates, cats, chinchillas, and birds also seem to employ HPR with auditory sequences. Further, there is recent evidence that animals unable to produce speech sounds can nevertheless discriminate between closely related phonemes. Thus, it appears that human speech perception employs prelinguistic abilities shared with other animals to distinguish between phonemic groupings. Of course, use of speech for communication also requires establishment of phonemic groupings as symbols, and sequential arrangement of these symbols, by rule, to convey the desired message. Identification of Components and their Order (ICO) for auditory sequences is limited to humans. ICO involves verbal categorization and storage of the names for successive auditory items as they appear, followed by retrieval or the names in the order stored. Thus, direct identification of the order of sounds within auditory sequences rests upon verbal ability, which provides an explanation for the difficulty that aphasics have in identifying order within nonverbal sequences. Much confusion in the literature on auditory sequence perception seems to have resulted from a failure to differentiate between HPR and ICO.