Smoothing
We have already noted that earlier ingliding diphthongs have become monophthongs: 
in near, /εə/ > /ε:/ in square. This is also true of 
in poor, 
in pore, and (presumably) 
in pure. This development has also occurred in original triphthongs, giving tower /ta:/ and fire /fa:/ in working-class speech – the vowel /a:/ occurs only as a result of smoothing. In middle class speech, however, in which /a:/ is more central, /a:/ does not occur, and tar and tower are homophonous.
This historical process involving lowering before /ə/ and then loss of /ə/ is paralleled by a synchronic phonological process which carries across morpheme and word boundaries, and extends to additional vowels. (In examining the following examples, recall that East Anglia has /ə/ in most unstressed syllables where many other accents have 
.) The full facts can be summarized as follows:
Thus, do it is homophonous with dirt and going rhymes with lawn. The vowels /æ:/, /a:/, 
occur only as a result of smoothing. Interestingly, some speakers in Norwich pronounce towel as /tз:l/. Smoothing is most typical of the northern zone of East Anglia, but is currently spreading southwards (Trudgill 1986).
