Syllable-based processes

Recognizing the syllable as a phonological unit, and moreover a unit with the internal structure hypothesized in (1), allows us to write improved versions of some phonological rules. Sometimes, what determines or conditions a phonological process or change is simply the nature of an adjacent segment: for example, we have seen that the nasal of the prefix in- assimilates to a following consonant, and that sounds frequently become voiced between other voiced segments. However, in other cases it is the position of a sound within the syllable that dictates its phonetic shape. In turn, improvements in our statement of phonological rules may help justify or validate the constituents we have proposed for the syllable.

First, the notion of the syllable in general, and the onset constituent in particular, helps us to state the environment for aspiration of voiceless stops more accurately. Our current, rather informal version predicts aspiration in absolute word-initial position; as we already know, /p t k/ surface as aspirated in pill, till, kill, but not when preceded by /s/ in spill, still, skill. However, this is not the whole story, since we can also observe aspiration in repair, return, record, though not in respond, disturb, discard. In these examples, the voiceless stops are medial, not initial in the word: but in repair, return, record, they are the sole constituents of the onset for syllable two, and therefore initial in that syllable. As for respond, disturb, discard, here also /p t k/ are part of the onset, but this time preceded by /s/; and since a preceding /s/ inhibits aspiration in onsets word-initially, we should not be surprised that the same pattern is found in onsets wordmedially. In short, aspiration of voiceless stops takes place, not at the beginning of the word, but at the beginning of the onset.

Similar support can be found for the second major constituent of the syllable, namely the rhyme. As we have seen already, many varieties of English have two main allophones of /l/, clear or alveolar [l] and dark, velarized, in complementary distribution. However, stating the nature of this complementarity is not entirely straightforward. Earlier, the rule for velarization of /l/ was informally stated as taking place after the vowel in a word, giving the correct results for clear versus hill, for instance. This works well enough when we are only dealing with word-initial versus word-final clusters, but it leaves a grey area in wordmedial position, where we find darkin falter, hilltop, but clear [l] in holy, hilly. Again, this is resolvable if we state the rule in terms of the syllable: clear [l] appears in onset position, and darkin the coda. In fact, this process does not only provide evidence for the contrast between onset and coda position, but for the superordinate rhyme constituent, which consists of the nucleus plus the optional coda. In cases of consonant syllabification, where /l/ (or another sonorant consonant) comes to play the role of a vowel and therefore occupies the nuclear position, as in bottle, little, we find the dark allophone. /l/-velarization, then, takes place in syllable rhymes, as shown in (7).