Phonological history of English t Note : This page contains IPA phonetic symbols in Unicode . See IPA chart for English for a pronunciation key . `` Flapping '' redirects here . For other uses of the term , see Flap . The voiceless alveolar plosive phoneme /t/ has undergone a number of changes in the phonological history of the English language . Two particularly salient phenomena , flapping and t-glottalization , are discussed here . Flapping Flapping ( more accurately 'tapping' , see below ) is a phonological process found in many dialects of English , especially American , Canadian and Australian English , by which prevocalic /t/ and /d/ surface as the alveolar tap [ ɾ ] after sonorants other than ŋ , m , and ( in some environments ) l . after vowel : butter after r : barter after l : faculty ( but not immediately post-tonic : alter -- > al [ tʰ ] er , not *al [ ɾ ] er ) The term `` flap '' is often used as a synonym for the term `` tap '' , but the two can be distinguished phonetically . A flap involves a rapid movement of the tongue tip from a retracted vertical position to a ( more or less ) horizontal position , during which the tongue tip brushes the alveolar ridge . A tap involves a rapid backwards and forwards movement of the tongue tip . The sound referred to here is the alveolar tap [ ɾ ] , not the flap [ ɽ ] , and hence `` tapping '' is the correct term from a phonetic point of view ( see also Flap consonant ) . The term `` flapping '' is , however , ingrained in much of the phonological literature , so it is retained here . However , no languages are known to contrast taps and flaps in the first place . Flapping/tapping is a specific type of lenition , specifically intervocalic weakening . For people with the merger these following words sound the same or almost the same : matter/madder grater/grader metal/medal For most ( but not all ) speakers the merger does not occur when an intervocalic /t/ or /d/ is followed by a syllabic 'n' , so written and ridden remain distinct . A non-negligible number of speakers ( including pockets in the Boston area ) lack the rule that glottalizes t and d before syllabic n , and therefore flap/tap /t/ and /d/ in this environment . Pairs like potent  : impotent , with the former having a preglottalized unreleased t or a glottal stop ( but not a flap/tap ) and the latter having either an aspirated t or a flap/tap , suggest that the level of stress on the preceding vowel may play a role in the applicability of glottalization and flapping/tapping before syllabic n . Flapping/tapping does not occur in most dialects when the /t/ or /d/ immediately precedes a stressed vowel , as in retail , but can flap/tap in this environment when it spans a word boundary , as in `` got it '' -- > [ gɑɾɪt ] , and when a word boundary is embedded within a word , as in `` buttinsky '' . Australian English also flaps/taps word-internally before a stressed vowel in words like `` fourteen '' . In many accents , such words as riding and writing continue to be distinguished by the preceding vowel : though the consonant distinction is neutralized , the underlying voice distinction continues to select the allophone of the /aɪ/ phoneme preceding it . Thus for many North Americans , riding is [ ɹɑɪɾɪŋ ] while writing is [ ɹɐɪɾɪŋ ] . Vowel duration may also be different , with a longer vowel before tap realisations of /d/ than before tap realisations of /t/ . At the phonetic level , the contrast between /t/ and /d/ may be maintained by these non-local cues , though as the cues are quite subtle , they may not be acquired/perceived by others . A merger of /t , d/ can then be said to have occurred . The cluster [ nt ] can also be flapped/tapped ; the IPA symbol for a nasal tap is [ ɾ̃ ] . As a result , in quick speech , words like winner and winter can become homophonous . Flapping/tapping does not occur for most speakers in words like 'carpenter ' and 'ninety' , which instead surface with [ d ] . http : //alt-usage-english.org/center_for_dentists.wav `` a sentence about a center for dentists , at the frontal edge of the continent , by the Atlantic ocean '' . A similar process also occurs in other languages , such as Western Apache ( and other Southern Athabaskan languages ) . In Western Apache , intervocalic /t/ similarly is realized as [ ɾ ] in intervocalic position . This process occurs even over word boundaries . However , tapping is blocked when /t/ is the initial consonant of a stem ( in other words tapping occurs only when /t/ is stem-internal or in a prefix ) . Unlike English , tapping is not affected by suprasegmentals ( in other words stress or tone ) . T-glottalization T-glottalization is a process that occurs for many English speakers , that causes the phoneme /t/ to be pronounced as the glottal stop [ ʔ ] in certain positions . In some dialects of American and Canadian English , notably those of New Britain , Connecticut and Newfoundland , /t/ is pronounced as [ ʔ ] when occurring before a syllabic 'n ' as in `` written '' [ ɹɪʔn̩ ] . In many dialects of English English , all intervocalic `` t '' 's are realized as [ ʔ ] . It 's also quite common in many varieties of English to pronounce `` t '' 's in final position as [ ʔ ] . References ^ Giegerich , Heinz J. ( 1992 ) . English Phonology , pp. 225 , 241 . Cambridge University Press . Categories : English phonology | Phonology | Splits and mergers in English phonology /t/ /d/ [ ɾ ] al [ tʰ ] er *al [ ɾ ] er [ ɾ ] [ ɽ ] /t/ /d/ /t/ /d/ /t/ /d/ [ gɑɾɪt ] /aɪ/ [ ɹɑɪɾɪŋ ] [ ɹɐɪɾɪŋ ] [ nt ] [ ɾ̃ ] [ d ] /t/ [ ɾ ] /t/ /t/ /t/ [ ʔ ] /t/ [ ʔ ] [ ɹɪʔn̩ ] [ ʔ ] [ ʔ ] 