Speech perception is the ability to comprehend speech through listening. Mankind is constantly being bombarded by acoustical energy. The challenge to humanity is to translate this energy into meaningful data. Speech perception is not dependent on the extraction of simple invariant acoustic patterns in the speech waveform. The sound’s acoustic pattern is complex and greatly varies. It is dependent upon the preceding and following sounds (Moore, 1997). According to Fant (1973), speech perception is a process consisting of both successive and concurrent identification on a series of progressively more abstract levels of linguistic structure. Nature of Speech SoundsPhonemes are the smallest unit of sound. In any given language words are formed by combining these phonemes. English has approximately 40 different phonemes that are defined in terms of what is perceived, rather than in terms of acoustic patterns. Phonemes are abstract, subjective entities that are often specified in terms of how they are produced. Alone they have no meaning, but in combination they form words (Moore, 1997).In speech there are vowels and consonants. Consonants are produced by constricting the vocal tract at some point along its length. These sounds are classified into different types according to the degree and nature of the constriction. The types are stops, affricates, fricatives, nasals, and approximants. Vowels are usually voiced and are relatively stable over time Moore, 1997).Categorical PerceptionCategorical perception implies definite identification of the stimuli. The main point in this area is that the listener can only correctly distinguish speech sounds to the extent that they are identified as different phonemes. Small changes to the acoustical signal may make little difference to the way the sound is perceived, yet other changes which are equally as small may produce a distinct change, altering the phoneme identity. People ...
