Is there a recent change in the depiction of English r sound from [r] to [ɹ]; if I understand it, now the regular English character [r] (the lowercase of the eighteenth letter of the Latin alphabet) is used for depiction of Spanish r sound (a trill), and the upside down [ɹ] is assigned to represent the English r sound.
In case I failed to express myself here is what I mean: For the word solarium IPA pronunciation was [səˈlɛərɪəm], now should we write it as [səˈlɛəɹɪəm]?
If my assumption is correct does your book's latest edition reflect that change?
No need to panic. It's a false alarm.
Needless to say, there has been no such change in the IPA, recent or otherwise. I have not changed the transcription of this consonant in LPD, nor do I plan to. The writer’s assumption is NOT correct. Oh, and by the way, solarium is not transcribed as səˈlɛərɪəm in any edition of LPD. (For BrE I write səˈleəriəm.)
I haven’t bothered to track down exactly when the symbols r and ɹ received their current definitions, but it was certainly more than a century ago.
(I’ve just inspected the 1902 edition of the IPA Chart to confirm this — see fragment below. As usual, click to enlarge. Note that r is listed as (consonne) roulée, ‘trill’, and ɹ as fricative. By the way, the inverted g and inverted ʒ at the end of the fricatives linguales in this chart are glossed in the accompanying explanation as des sons Tcherkesses ‘Circassian sounds’ — possibly they are retroflex, i.e. the sounds we would nowadays write ʂ, ʐ.)
IPA symbols have always had to be interpreted in accordance with conventions implicitly or explicitly defined by the transcriber who uses the symbols.
In the words of the IPA Handbook (CUP 1999; p. 29),
Any transcription is connected to a speech event by a set of conventions. In the case of an impressionistic (‘general phonetic’) transcription, the conventions are precisely those lying behind the IPA Chart, indicating for instance that the phonetic value of [ʔ͡k] is a simultaneous velar and glottal closure. In the case of a phonemic transcription, the conventions also include the ’phonological rules’ of the particular language which determine the realization of its phonemes, such as the fact that for some varieties of English the lateral phoneme /l/ is realized with an accompanying secondary articulation ([ɫ]) when not followed directly by a vowel or /j/ in the same word. Likewise, the realizational information which is not explicit in a particular allophonic transcription is, in principle, provided by conventions.
It is convenient (= practical and sensible) for us to use the same phonemic symbol t for the unaspirated dental plosive of French, the aspirated dental plosive of Swedish, the unaspirated alveolar plosive of Czech, and the aspirated alveolar plosive of English.
In general, phonemic symbols should be as simple as possible. That means letters of the ordinary lower-case Roman alphabet in preference to special letters such as ɛ ɹ ɫ, and the avoidance of diacritics as far as possible. For detailed discussion of the issues involved, see for example Appendix A (Types of Phonetic Transcription) of Daniel Jones’s classic An Outline of English Phonetics, or Part I (Introduction) of David Abercrombie’s English Phonetic Texts (London: Faber and Faber, 1964, or of course the IPA Handbook or its predecessor, the 1949 Principles of the IPA booklet.
So the English consonant at the beginning of red can be written phonemically as r or allophonically ~ impressionistically ~ general-phonetically as ɹ. Both ways of writing it are ‘IPA’; both are equally ‘scientific’; both convey the same information.
The problem is how to convey this point clearly to non-specialists such as my correspondent.
Just to confirm, in the transcribed texts of the 1902 Maître Phonétique the symbol r is used for all the various r-sounds of both English and French, even though at that date the notion of ‘phoneme’ in the modern sense had not yet been developed.