Speech production the larynx that then is modified by the vocal tract into different vowels and consonants. However speech production can occur without the use of the lungs and glottis in alaryngeal speech by using the upper parts of the vocal tract. An example of such alaryngeal speech is Donald Duck talk. The vocal production of speech may be associated with the production of hand gestures that act to enhance the comprehensibility of what is being said. The development of speech production throughout an individual's life starts from an infant's first babble and is transformed into fully developed speech by the age
Speech perception it is unclear how indexical information (e.g. talker-identity) is encoded/decoded along with linguistically relevant information. The direct realist theory of speech perception (mostly associated with Carol Fowler) is a part of the more general theory of direct realism, which postulates that perception allows us to have direct awareness of the world because it involves direct recovery of the distal source of the event that is perceived. For speech perception, the theory asserts that the objects of perception are actual vocal tract movements, or gestures, and not abstract phonemes or (as in the Motor Theory) events that are causally antecedent to