Allophonic relations

As explained in the preceding chapter, the focus of phonology is the mental rules which govern the pronunciation of words in a given language. Certain facts about pronunciation simply cannot be predicted by rule, for example that in English the word sick is pronounced [sɪk] and sip is pronounced [sɪp]. Hence one fundamental component of a language is a lexicon, a list of words (or morphemes – parts of words), which must provide any information which cannot be predicted by rules of the language. However, much about the pronunciation of words can be predicted. For example, in the word tick the initial voiceless consonant t is phonetically aspirated, and is phonetically [t h ɪk]. This aspiration can be demonstrated visually by dangling a tissue in front of the mouth when saying the word: notice that when you pronounce t, the tissue is blown forward. In comparison, t in the word stick is not aspirated (thus, the tissue is not blown forward), so this word is transcribed as [stɪk]. This fact can be predicted by rule, and we now consider how this is done.