Consonants+and+Vowels

In general, there are two large classes of speech sounds: consonants and vowels. Consonants by nature are brief and transitional and have identification boundaries which are sharply defined. These boundaries enable different consonants to be discerned accurately.

**Laterality**
consonants are perceived in a wholly different manner from vowels -they are composed of segments of rapidly changing frequencies which includes the duration, direction and magnitude of sounds segments interspersed with periods of silence. -These transitions occur in 50 msecs or less which in turn requires that the left half of the brain take responsibility for perceiving them. -Moreover, many consonants are silent. - more a function of "categorical perception"
 * Left Hemisphere:** Consonants more involved

Vowels are more continuous in nature -Consist of a slowly changing or steady frequencies with transitions taking 350 or more msec. -Vowels are more like natural environmental sounds which are more continuous in nature, even those which are brief such as a snap of a twig. - yield to nuclei involved in "continuous perception" -Vowels are particularly important considering their significant role in communicating emotional status and intent.
 * Right Hesiphere:** Vowels more involved

The differential involvement of the right and left hemisphere in processing consonants and vowels is a function of their neuroanatomical organization and the fact that the left cerebrum is specialized for dealing with sequential information. Moreover,the left temporal lobe is able to make fine temporal discriminations with intervals between sounds as small as 50 msec. However, the right hemisphere needs 8-10 times longer and has difficulty discriminating the order of sounds if they are separated by less than 350 msecs.

The left temporal lobe acts on both vowels and consonants during the process of perception so as to sort these signals into distinct patterns of segments via which these sounds become classified and categorized.