3.2 Phonemes and allophones

　 In phonetic transcription of sounds, the unit of representation is segment. Looked at from a phonological point of view, some segments distinguish words, others don't. For example, the two liquids [l] and [r] distinguish lead and read. When we listen to more words that contain the lateral liquid, as in deal and slight, we find the liquid in each of these words is a separate segment. The one in lead is clear, [l]; the one in deal is dark [], and the one in slight is voiceless []. These variants are called allophones. They can be grouped into a phonological unit called a phoneme. A phoneme is an abstract sound unit. The phonemic symbol is placed between slashes (/ /). In the case of lateral liquids, [] appears after vowels, [] after voiceless consonants, and [l] elsewhere. As [l] is more widely distributed than the other two, we choose /l/ as the phonemic symbol. The relation between the phoneme and its allophones can be shown in the following figure:

　　Segments that are phonemes in one language may be allophones in another. In English, the two liquids /l/ and /r/ are phonemes, but in Korean the two segments are allophones. An important part of phonological analysis deals with how to discover phonemes of a language, a point to which we turn in the next section.