Peter Roach
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affricate sound or as two separate sounds, and the question depends on whether these are to be regarded as separate phonemes or not. It is usual to regard /ʧ/ and /ʤ/ as affricate phonemes in English (usually symbolised č , j by American writers); /ts, dz, tr, dr / also occur in English but are not usually regarded as affricates. The two phrases 'why choose' /waɪ ʧuːz/ and 'white shoes' /waɪt ʃuːz/ are said to show the difference between the /ʧ/ affricate (in the first example) and separate /t/ and /ʃ/ (in the second).
air-stream All speech sounds are made by making air move. Usually the air is moved outwards from the body, creating an egressive airstream; more rarely speech sounds are made by drawing air into the body - an ingressive airstream. The most common way of moving air is by compression of the lungs so that the air is expelled through the vocal tract. This is called a pulmonic airstream (usually an egressive pulmonic one, but occasionally speech is produced while breathing in). Others are the glottalic (produced by the larynx, with closed vocal folds; it is moved up and down like the plunger of a bicycle pump) and the velaric (where the back of the tongue is pressed against the soft palate, or velum, making an air-tight seal, and then drawn backwards or forwards to produce an airstream). Ingressive glottalic consonants (often called implosives) and egressive ones (ejectives) are found in many non-European languages; click sounds (ingressive velaric) are much rarer, but occur in a number of southern African languages such as Hottentot, Xhosa and Zulu. Speakers of other languages, including English, use click sounds for non-linguistic communication, as in the case of the "tut-tut" (American "tsk-tsk") sound of disapproval. allophone Central to the concept of the phoneme is the idea that it may be pronounced in many different ways. In English (BBC) we take it for granted that the /r/ sound in 'ray' and 'tray' are "the same sound" (i.e. the same phoneme), but in reality the two sounds are very different - the /r/ in 'ray' is voiced and nonfricative, while the /r/ sound in 'tray' is voiceless and fricative. In phonemic transcription we use the same symbol /r/ for both (the slant brackets indicate that phonemic symbols are being used), but we know that the allophones of /r/ include the voiced non-fricative sound and the voiceless fricative one. Using the square brackets that indicate phonetic (allophonic) symbols, the former is [̻] and the latter []. In theory a phoneme can have an infinite number of allophones, but in practice for descriptive purposes we tend to concentrate on the ones that occur most regularly.