The /h/ sound is spelled with <h> or <wh> in who. The /ʧ/ sound is spelled with <ch> or <tch>.
This is a contrast between a glottal fricative and an alveolar affricate, both voiceless, only occurring in syllable-initial position. Although the /h/ can be difficult for some learners, the contrast is not a problem.
Interesting pairs include:
The mean density value is 3.5%. The lists make 56 semantic distinctions, a loading of 51%.
had Chad haft chaffed hair chair hairs chairs hairy chary half chaff hap chap happed chapped happing chapping haps chaps hard Chard hare chair hared chaired haring chairing hares chairs harm charm harmed charmed harming charming harms charms Harriet chariot hart chart has Chas haste chased hasten chasten hastened chastened hastening chastening hastens chastens hat chat hats chats hatter chatter hatters chatters haw chaw haws chaws hawed chawed hawing chawing hawk chalk hawked chalked hawking chalking hawks chalks hear cheer hearing cheering hears cheers heart chart harts charts hearted charted heat cheat heated cheated heating cheating heats cheats heater cheetah heaters cheetahs heck Czech hecks Czechs here cheer Herne churn Herr chair hick chick hicks chicks hickory chicory hide chide hides chides hiding chiding hilly chilly hillier chillier hilliest chilliest hilly Chile hints chintz hive chive hives chives hoar chaw hoar chore hoax chokes hock chock hocked chocked hocking chocking hocks chocks hoes chose Hoo chew hop chop hopped chopped hopping chopping hops chops hopper chopper hoppers choppers Horley Chorley hose chose house chows how chow howdah chowder howdahs chowders hubby chubby hug chug hugged chugged hugging chugging hugs chugs hum chum hums chums hummed chummed humming chumming hump chump humps chumps hunk chunk hunks chunks hurl churl hurls churls who chew whore chaw whores chaws whore chore whores chores whose chews
John Higgins, Shaftesbury, December 2010.