April McMahon

90 AN INTRODUCTION TO ENGLISH PHONOLOGYThese Vowel Shift alternations (so-called because the patterns reflectthe operation of a sound change called the Great Vowel Shift severalhundred years ago) involve pairs of phonemes which very clearly contrastin English – the members of the PRICE and KIT, FLEECE and DRESS,and FACE and TRAP pairs of standard lexical sets. Minimal pairs arecommon for all of these (take type and tip, peat and pet, lake and lack, forinstance). However, the presence of each member of these pairs can bepredicted in certain contexts only; and native speakers tend to regard thepairs involved, such as divine and divinity, as related forms of the sameword. This is not neutralisation, because the context involved is notspecifically phonetic or phonological: it is morphological. That is, whatmatters is not the length of the word, or the segment following the vowelin question, but the presence or absence of one of a particular set ofsuffixes. In underived forms (that is, those with no suffix at all) we findthe tense or long vowel, here /aI/, /i/ or /eI/; but in derived forms, witha suffix like -ity, -ar, -acy, -ation, a corresponding lax or short vowel /I/,/ε/ or // appears instead. This alternation is a property of the lexicalitem concerned; vowel changes typically appear when certain suffixesare added, but there are exceptions like obese, with /i/ in the underivedstem, and the same vowel (rather than the /ε/ we might predict) inobesity, regardless of the presence of the suffix -ity. Opting out in this waydoes not seem to be a possibility in cases of neutralisation, but is quitecommon in cases of morphophonemics, or the interaction betweenphonology and morphology.To put it another way, not all alternations involving morphology arecompletely productive. Some are: this means that every single relevantword of English obeys the regularity involved (so, all those nouns whichform their plural using a -s suffix will have this pronounced as [s] aftera voiceless final sound in the stem, [z] after a voiced one, and [Iz] aftera sibilant; not only this, but any new nouns which are borrowed intoEnglish from other languages, or just made up, will also follow thispattern). Others are fairly regular, but not entirely so: this goes for theVowel Shift cases above. And yet others are not regular at all, but aresimply properties of individual lexical items which children or secondlanguagelearners have to learn as such. The fact that teach has the pasttense taught is an idiosyncrasy of modern English which has to bemastered; but although knowing this relationship will help a learner ofEnglish to use teach and taught appropriately, it will not help when itcomes to learning other verbs, because preach does not have the pasttense *praught, and caught does not have the present tense *ceach. Knowingwhere we should draw the line between extremely regular cases whichclearly involve exceptionless rules or generalisations, fairly regular ones