The /aɪ/ diphthong is spelled <iCe>, <i>, <y> and <ey> in eye, besides occurring in the letter names I and Y. The /aʊ/ diphthong is spelled <ou> or <ow>.
This is a contrast between two closing diphthongs with similar starting positions but different directions of movement. It is not a problem for learners.
Interesting pairs include:
alliance allowance
confined confound
The density figure is 8.95%. The set makes 105 semantic contrasts giving a loading of 55%.
aisle owl aisles owls alliance allowance alliances allowances ally allow allied allowed allies allows allying allowing arise arouse arises arouses arising arousing ayah hour ayahs hours bide bowed bight bout bights bouts bind bound binding bounding binds bounds binder bounder binders bounders brine brown brines browns briny brownie buy bough buys boughs buy bow buys bows buying bowing buyer bower buyers bowers by bough by bow bye bough byes boughs bye bow byes bows confined confound cried crowd dial dowel dials dowels diary dowry diaries dowries dice douse diced doused dices douses dicing dousing die dhow dies dhows dine down dined downed dines downs dining downing dire dower dormice dormouse dries drowse dyer dower dyers dowers espies espouse eye ow eyelet owlet eyelets owlets file foul filed fouled files fouls filing fouling find found finding founding finds founds finder founder finders founders flier flour fliers flours flier flower fliers flowers flight flout flighted flouted flighting flouting flights flouts fry Frau Giles jowls grind ground grinding grounding grinds grounds hi how hie how hies house high how hind hound hinds hounds hired Howard I ow iced oust I'll owl ire hour isle owl isles owls knight knout knights knouts liar lour liars lours lice louse light lout lights louts mice mouse mind mound minds mounds miser mouser misers mousers my mow nice nous nigh now night knout nights knouts nine noun nines nouns pined pound plant-lice plant-louse ply plough plied ploughed plies ploughs plying ploughing pride proud pry prow pries prows pyre power pyres powers rebind rebound resigned resound ride rowed right rout righted routed righting routing rights routs rind round rinds rounds rise rouse rises rouses rising rousing rye row shire shower shires showers shrew-mice shrew-mouse sigh sow sighs sows signed sound sire sour sired soured sires sours siring souring sky scow skies scows sly Slough spies spouse spite spout spited spouted spites spouts spiting spouting sprite sprout sprites sprouts stride Stroud thy thou tight tout tights touts tine town tines towns tiny townee tire tower tired towered tires towers tiring towering titmice titmouse trial trowel trials trowels trite trout Tyne town tyre tower tyres towers unbind unbound unwind unwound vial vowel vials vowels vie vow vied vowed vies vows vying vowing vile vowel whined wound wind wound woodlice woodlouse Y wow Y's wows
John Higgins, Shaftesbury, December 2009