The /æ/ vowel is spelled <a> followed by two consonants or by one consonant in a monosyllable. The /ɔɪ/ diphthong is spelled <oi> or <oy>.
This contrast is between a short vowel and a diphthong with the sounds well separated in the mouth, so it should not cause any problems.
Interesting pairs include:
Since the /ɔɪ/ is very infrequent in the language, the density value is unexpectedly high at 4.2%. The pairs make 20 semantic contrasts, giving a loading of 60.1%.
Al oil Ali oily aster oyster asters oysters bad buoyed caff coif caffs coifs can coign cans coigns can coin cans coins canned coined canning coining canna coiner cannas coiners cat quoit cats quoits clad cloyed dally doily dallies doilies grand groined hast hoist Jan join jazz joys lads Lloyd's latter loiter massed moist pant point panted pointed panting pointing pants points tracker troika trackers troikas
John Higgins, Shaftesbury, November 2009