Allophonic variation

If contextual allophonic variation was all we had to contend with, the phonemic to acoustic process would still be quite simple all we would need is a model whereby each phoneme had a range of possible realisations the process of conversion fi-om one domain to the other would still be relatively trivial. 

Given the word sequence, our next job is to determine the phone sequence. In considering this, we should recall the discussions of Sections 7.3.2, 7.3.6 and 8.1.3. There we stated that there was considerable choice in how we mapped from the words to a sound representation, with the main issue being whether to choose a representation that is close to the lexicon (e.g. phonemes) or one that is closer to the signal (e.g. phones with allophonic variation marked). 

One of the main reasons we are interested in syllables is that pattern of syllables within a word, and the pattern of phonemes within a syllable helps determine much of the phonemic variation due to allophones and coarticulation. Hence it is often useful to assign a basic constituent structure to describe the structure of phonemes internal to a syllable. We will explain one way of doing this, in which four basic constituents are used, called the onset, rhyme, nucleus and coda. The syllable structure for the single syllable word strength in these terms is ... 

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