Standard use of brackets in ipa (2005)

(a) The sound identified as a voiced alveolar frictionless continuant (liquid, approximant) is conventionally signalled with the phonetic symbol /r/. But it is not the standard symbol offered by the International Phonetic Association. It is used for the sake of convenience. It is at hand in printing offices, so it is easier to handle. Nevertheless, the standard symbol displayed in the International Phonetic Alphabet is /ɹ/.

(b) It is BrE (RP, Received Pronunciation, Royal Pronunciation) which is the standard in the table below. AmE is viewed as a dialect in comparison with it.

	Allophone /free variant	Description	Examples	Notes
	[r] = [ɹ]	voiced alveolar frictionless continuant / liquid	[ˈræbɪt], [bred], [ˈkærət]	BrE/AmE
	[r̥]	devoiced alveolar frictionless continuant / liquid	[kr̥aɪ], [pr̥eɪ]	BrE/AmE
	[d͡r] = /dr/	voiced post-alveolar affricate	[d͡rɪŋk]	It sounds similar to /dʒ/ in some dialects. BrE/AmE
	[t͡r̥] = /tr/	voiceless post-alveolar affricate	[t͡r̥eɪn]	It sounds similar to /t͡ʃ/ in some dialects. BrE/AmE
	[ʳ]	linking /r/ and intrusive /r/	linking /r/: [ðəˈtit͡ʃəʳənd̥hɪz̥ˈkɒliˑɡz], intrusive /r/: [ˈæfrɪkəʳənd], [ðɪ.aɪˈdɪəʳəvˈlæŋɡwɪdʒ]	in non-rhotic dialects, BrE
	[ɚ]	rhotic /ə/	[ˈsɪŋɚ]	in rhotic dialects, AmE, a free variant
	[ɝː]	rhotic /ɜː/	[bɝˑd], [pɝt]	in rhotic dialects, AmE, a free variant
	[r̩]	syllabic voiced alveolar frictionless continuant / liquid	/ˈlɪbᵊr‿əl/¹ [ˈlɪbr̩l], /ˈlaɪbrərɪ/² [ˈlaɪbr̩rɪ], [ˈvɪʒn̩r̩ɪ]³	BrE, ¹(Wells 1990), ²(Wells 1990), ³(Roach 1991)
	[r̥̍]	syllabic devoiced alveolar frictionless continuant / liquid	[ˈvetr̥̍n̩]¹	BrE, ¹(Roach 1991)
	[ɽ] = [ɻ]	retroflex voiced alveolar frictionless continuant	[kɑːɽ]	AmE, a free variant
	[ɽ̍]	syllabic retroflex voiced alveolar frictionless continuant	[bɽ̍d]	AmE, a free variant
	[ɽ̥̍]	syllabic retroflex devoiced alveolar frictionless continuant	[pɽ̥̍t]	AmE, a free variant

(4) A strange case

The AmE pronunciation of the word is given /ˈmæt̬ ᵊr/ (Wells 1990), /ˈmæt̬.ɚ/ (Jones 1999) in pronunciation dictionaries. What does the phonetic symbol /t̬/ stand for?

Phonetically /t̬/ is a voiced alveolar tap (flap). It sounds like a quick English /d/, and also like the /r/ of some languages. For many Americans, it is actually identical with their /d/ in the same environment, so that AmE /ˈʃᴧt̬ ᵊr/ identical with /ˈʃᴧd ᵊr/.

(Wells 1990:703, with my amendments)

In contrast with the Longman dictionary ‘phonetician’ explanation, the Cambridge English pronouncing dictionary gives a user friendly one:

The use of phonemic transcription in works on pronunciation (including this one) has remained in the “realist” tradition established by Jones, while approaches to the phoneme by theoretical phonologists have changed radically during recent decades and become much more abstract. There are a few exceptions to our general use of the phoneme principle that should be mentioned here, however. One is the use, in American pronunciations, of the [ ̬] diacritic to indicate the voicing and “flapping” of /t/ in words such as /ˈɡet̬.ɪŋ/, and /ˈbet̬.ɚ/. This is an important feature of American pronunciation, but speakers of British English find it difficult to apply the rule which determines when /t/ is voiced and/or flapped.

(Jones 1999:viii, with my amendments)

There are two more examples presented in a very accurate display below. As can be seen, there is not any difference between the pronunciations of the last syllables in fact because they are preceded by syllables ending in retroflex rhoticity, [ɻ] in (1) and [ɝˑ] in (2).

	Spelling	BrE, broad transcription	AmE
			Broad transcription	Narrow transcription
(1)		/ˈpɑːtɪ/	/ˈpɑːrt̬ɪ/	[ˈp ͪɑˑɻ.ɽɪ]
(2)		/ˈbɜːdɪ/	/ˈbɝː.dɪ/	[ˈb̥ɝˑ.ɽɪ]
	(Jones 1999:194, with my amendments)

So what does the phonetic symbol /t̬/ stand for? It is a voiced alveolar flap/tap which it substitutes in transcription. It is a /ɾ/. It is significantly different from /t/, which is a voiceless alveolar plosive, from a phonetician’s point of view. It holds true for Hungarian pronunciation, in which there are three distinct phonemes, /ɾ/, /t/, /d/, e.g. ‘an administrative county in the former Kingdom of Hungary’ /ˈbɛɾɛɡ/, /ˈbɛtɛɡ/ and ‘a valley in Miskolc’ /ˈbɛdɛɡvølɟ/.

‘International Phonetic Alphabet.’ Wikipedia : the free encyclopedia. Last modified: 13-05-2013 Retrieved: 14-05-2013

Wells, John Christopher. Longman pronunciation dictionary. Harlow : Longman, © 1990,

ISBN 0-582-05383-8