The /h/ sound is spelled with <h> or <wh> in who. The /n/ sound is spelled with <n>, <nn> or <gn> in gnash.
This is a contrast between a voiceless glottal fricative and a voiced alveolar nasal continuant. It can only occur initially or medially before a stressed syllable. It is not a problem.
Interesting pairs include:
humorous numerous
The mean density value is 1.2%. The lists make 98 semantic distinctions, a loading of 53%.
ahoy annoy hack knack hacks knacks hacker knacker hackers knackers hag nag hags nags hail nail hailed nailed hails nails hailing nailing hair ne'er hale nail hap knap happed knapped happing knapping haps knaps hap nap happed napped happing napping haps naps happy nappy hark nark harked narked harking narking harks narks harrow narrow harrowed narrowed harrowing narrowing harrows narrows hash gnash hashed gnashed hashes gnashes hashing gnashing hat gnat hats gnats hat Nat hatter natter hatters natters haughty naughty haughtier naughtier haughtiest naughtiest haughtily naughtily haughtiness naughtiness haulm norm haw gnaw hawed gnawed hawing gnawing haws gnaws hay née Hayling nailing haze neighs hazel nasal hazels nasals he knee head Ned heady Neddy heal kneel healed kneeled healing kneeling heals kneels hear near hearing nearing hears nears hearer nearer hearse nurse hearses nurses heather nether heck neck hecks necks hector nectar heed knead heeded kneaded heeding kneading heeds kneads heed need heeded needed heeding needing heeds needs heed kneed heel kneel heeling kneeling heels kneels heeled kneeled heedful needful heedless needless height knight heights knights hell nell Herr ne'er hew knew hew new hews news hewed nude hewer newer hi nigh hick nick hicks nicks high nigh higher nigher highest nighest hill nil hippie nippy hit knit hits knits hitting knitting hit nit hits nits hitch niche hitches niches hives knives ho know hoar nor hoarse Norse hob knob hobs knobs hobble knobble hobbled nobbled hobbles knobbles hobbling nobbling hock knock hocked knocked hocking knocking hocks knocks hod nod hods nods hoe know hoes knows hoeing knowing hoes nose hoed node hole knoll holes knolls home gnome homes gnomes hone known Hoo gnu hook nook hooks nooks hope nope Horwich Norwich hose knows hose nose hosed nosed hoses noses hosing nosing hosier nosier hot knot hots knots hotted knotted hotting knotting hot not Houghton Norton house nous hovel novel hovels novels how now hub nub hubs nubs hue knew hue new hues hews Hugh knew Hugh new hull null hum numb hummed numbed humming numbing hums numbs humerus numerous humorous numerous Hun none Hun nun Huns nuns hut nut huts nuts hutted nutted whole knoll wholes knolls whore gnaw whores gnaws whore nor who gnu whose gnus
John Higgins, Shaftesbury, December 2010.