The contrast only occurs in syllable-initial position. Therefore the spelling of /t/ is <t>, or <th> in Thai. The /h/ sound is <h> or <wh> in who. Notice how the homograph tear makes pairs with hair and hear.
The contrast is between a plosive and a fricative, both voiceless and well separated in the mouth. Although the /h/ sound itself is difficult for some speakers, the contrast is not a problem for learners.
The only mildly taboo word pair is turd/heard.
This contrast is exploited by the name of a chain of fashion stores: Top Shop. Other interesting pairs include:
tankard hankered
tawse whores
terraces heresies
tinder hinder
tubby hubby
tumbler humbler
The mean density value is 1.7%. The list makes 140 semantic distinctions, a loading of 51%.
entail inhale entailed inhaled entailing inhaling entails inhales T he T's he's ta ha tack hack tacked hacked tacking hacking tacks hacks tackles hackles tag hag tags hags tail hail tailed hailed tailing hailing tails hails tail hale take hake tale hail tales hails tale hale talk hawk talked hawked talking hawking talks hawks talker hawker talkers hawkers tall hall tallow hallow tally Halle tamper hamper tampered hampered tampering hampering tampers hampers tangs hangs tank hank tanks hanks tankard hankered tanker hanker tankers hankers tap hap tapped happed tapping happing taps haps tar ha tardy hardy tardier hardier tardiest hardiest tardiness hardiness tare hair tares hairs tare hare tares hares tare Herr tarred hard tarry harry tarried harried tarries harries tarrying harrying tart hart tarts harts tart heart tarts hearts tarted hearted tartan hearten tartans heartens tartly Hartley tassel hassle tasseled hassled tassels hassles taste haste tasty hasty tastier hastier tastiest hastiest tastily hastily tat hat tats hats tatter hatter tatters hatters taunt haunt taunted haunted taunting haunting taunts haunts tawny horny tawse haws tawse whores tea he tear hair tears hairs tear hare tears hares teraing haring tear Herr tear hear tears hears tech heck techs hecks Ted head Teds heads Teddy heady tee he teeter heater teeters heaters teeth heath tell hell tells hells temp hemp ten hen tens hens tense hence tern Herne terraces heresies terrific horrific terse hearse tether heather tethers heathers Thai hi Thais hies Thai high Thailand highland tick hick ticks hicks tide hide tides hides tiding hiding tidings hidings tie hi tie hie ties hies tying hieing tie high tie-up high-up tie-ups high-ups tight height tights heights tighten heighten tightened heightened tightening heightening tightens heightens tike hike tikes hikes tilde Hilda till hill tills hills tilt hilt tilts hilts Tim him tinder hinder tined hind tinge hinge tinged hinged tinges hinges tingeing hingeing tint hint tinted hinted tinting hinting tints hints tip hip tips hips tire higher tire hire tired hired tires hires tiring hiring to Hoo to who toad hoed toast host toasted hosted toasting hosting toasts hosts toe ho toe hoe toeing hoeing toes hoes toed hoed tog hog togged hogged togging hogging togs hogs told hold told holed toll hole tolling holing tolls holes tolled holed tolled hold tomb whom tome home tomes homes tone hone toned honed tones hones toning honing too Hoo too who took hook tool who'll toot hoot tooted hooted tooting hooting toots hoots top hop topped hopped tops hops topping hopping tope hope toping hoping toped hoped topes hopes topper hopper toppers hoppers toques hoax tor hoar tors hoars tor whore tors whores torn horn torrid horrid Tory hoary tot hot tots hots totted hotted totting hotting totter hotter touch hutch touches hutches tough huff toughs huffs toughie huffy tow hoe tows hoes towed hoed towing hoeing towered Howard tub hub tubs hubs tubby hubby tuft huffed tug hug tugged hugged tugging hugging tugs hugs tumble humble tumbled humbled tumbles humbles tumbling humbling tumbler humbler tumid humid tumidity humidity tumour humour tumours humours tune hewn tunny honey tunnies honeys turbot Herbert turd heard turds herds turn Herne turtle hurtle turtles hurtles tusk husk tusks husks tussle hustle tussled hustled tussles hustles tussling hustling tut hut tutted hutted two Hoo two who twos whose
John Higgins, Shaftesbury, February 2010.