The terms tap and flap may be used interchangeably. Peter Ladefoged proposed for a while that it may be useful to distinguish between them; however, his usage has been inconsistent and contradicted itself even between different editions of the same text. The last proposed distinction was that a tap strikes its point of contact directly, as a very brief stop, and a flap strikes the point of contact tangentially: "Flaps are most typically made by retracting the tongue tip behind the alveolar ridge and moving it forward so that it strikes the ridge in passing." However, he later no longer felt that it was a useful distinction to make and preferred to use the word flap in all cases.
For linguists who make the distinction, the coronal tap is transcribed as [ɾ], and the flap is transcribed as [ᴅ], which is not recognized by the IPA. Otherwise, alveolars and dentals are typically called taps and other articulations flaps. No language contrasts a tap and a flap at the same place of articulation.
This sound is often analyzed and thus interpreted by native English-speakers as an 'R-sound' in many foreign languages. In languages for which the segment is present but not phonemic, it is often an allophone of either an alveolar stop ([t], [d], or both) or a rhotic consonant (like the alveolar trill or the alveolar approximant).
When the alveolar tap is the only rhotic consonant in the language, it may be transcribed /r/ although that symbol technically represents the trill.
Both the lenited and non-initial broad form of r. Often transcribed simply as /r/. The initial unlenited broad form is /rˠ/ (also transcribed as /ᵲ/ or /R/) while the slender form is /ɾʲ/ ([ð] in some dialects). See Scottish Gaelic phonology.
A tapped fricative is in effect a very brief fricative, with the tongue making the gesture for a tapped stop but not making full contact. This can be indicated in the IPA with the lowering diacritic to show full occlusion did not occur. Flapped fricatives are theoretically possible but are not attested.
Martínez-Celdrán, Eugenio; Fernández-Planas, Ana Ma.; Carrera-Sabaté, Josefina (2003), "Castilian Spanish", Journal of the International Phonetic Association, 33 (2): 255–259, doi:10.1017/S0025100303001373
Sjoberg, Andrée F. (1963), Uzbek Structural Grammar, Uralic and Altaic Series, 18, Bloomington: Indiana University
Šuštaršič, Rastislav; Komar, Smiljana; Petek, Bojan (1999), "Handbook of the International Phonetic Association: A guide to the use of the International Phonetic Alphabet", Journal of the International Phonetic Association, Cambridge: Cambridge University Press, 23 (2): 135–139, doi:10.1017/S0025100300004874, ISBN0-521-65236-7|chapter= ignored (help)
Trudgill, Peter; Hannah, Jean (2002), International English: A Guide to the Varieties of Standard English, 4th ed, p. 24
Valentin-Marquez, Wilfredo (2008), "Studies in Hispanic and Lusophone Linguistics", Studies in Hispanic and Lusophone Linguistics, 1 (2): 451–454, doi:10.1515/shll-2008-1031