The /m/ sound is spelled with <m>, <mm> or <mb> in comb. The /ʧ/ sound is spelled with <ch>, <tch>, <tu> in feature or <c> in cello.
This is a contrast between a voiced bilabial nasal continuant and a voiceless alveolar affricate. It is not a problem.
Interesting pairs include:
ermine urchin
femur feature
malice chalice
martyr charter
mason chasten
million Chilean
stammer stature
The mean density value is 2.6%. The lists make 118 semantic distinctions, a loading of 58%.
aim H amah archer amahs archers arm arch armies arches arming arching armour archer armours archers armoury archery army Archie beam beach beaming beaching beamed beached beam beech beseem beseech beseeming beseeching bomb botch bombing botching bombed botched bomber botcher bombers botchers bream breach cam catch coaming coaching comb coach combed coached combing coaching crumb crutch dim ditch dimming ditching dimmed ditched dumb Dutch dummy duchy dummies duchies ermine urchin fem fetch femur feature femurs features film filch filming filching filmed filched ham hatch hamming hatching hammed hatched him hitch hum hutch hymn hitch hymning hitching hymned hitched lam latch lambing latching lambed latched M etch ma'am match mace chase maces chases mad Chad Maine chain main chain mains chains Mali Charlie malice chalice mammies matches mange change map chap mapped chapped mapping chapping maps chaps mar char marring charring mars chars marred charred marcher charmer marchers charmers mare chair mares chairs marred Chard mart chart marts charts martyr charter martyred chartered martyring chartering martyrs charters Mary chary mason chasten masons chastens Matt chat mat chat matted chatted matting chatting mats chats matter chatter mattered chattered mattering chattering matters chatters Maud chawed maw chaw maws chaws maw chore maws chores mayor cvhair mayors chairs meat cheat meats cheats meet cheat meeting cheating meets cheats mellow cello mellows cellos mere cheer meres cheers merry cherry mete cheat meted cheated metes cheats meting cheating meter cheetah meters cheetahs mickle chicle mild child mill chill milled chilled mills chills milling chilling Millie Chile Millie chilli million Chilean millions Chileans mime chime mimed chimed mimes chimes miming chiming mine chine mines chines miner China mink chink minks chinks mints chintz mix chicks mizzle chisel mizzled chiselled mock chock mocked chocked mocking chocking mocks chocks moke choke mokes chokes monk chunk monks chunks monkey chunky moo chew mooing chewing moos chews mooed chewed mood chewed mop chop mopped chopped mopping chopping mops chops more chore Morley Chorley mortal chortle mortals chortles mow chow mows chows mows chose muck chuck mucked chucked mucking chucking mucks chucks muckle chuckle mug chug mugged chugged mugging chugging mugs chugs mum chum mums chums mum much mummy chummy mumps chumps myna China norm nautch palm parch palming parching palmed parched Pam patch perm perch perming perching permed perched ram ratch ream reach rim rich roam roach Rome roach scram scratch scramming scratching scrammed scratched scream screech screaming screeching screamed screeched some such stammer stature swim switch swimming switching team teach teaming teaching tummies touches tummy touchy whim which whim witch whom hooch
Credit: John Higgins