But some of the queries I receive show that this is not necessarily the case. Or at least people are not comfortable with the convention that slashes / / are used to enclose symbols for phonemes, but that symbols for speech sounds ~ realizations ~ allophones ~ variants properly go inside square brackets [ ]. (Or you can do as I do in this blog and merely embolden phonetic symbols without reference to their phonological status unless relevant.)
I would like to know your point of view about /eə/ and /ɛ:/.
Cruttenden lists [the change from the first to the second] among the "changes almost complete". Also Collins and Mees, in their Practical Phonetics and Phonology, have already opted for the /ɛ:/ symbol since 2003. The open /ɛ:/ is the only one found in Upton's ODP too. […]
I was wondering why both in your LPD and the EPD this alternative pronunciation is not transcribed. I might be wrong, but in my opinion, the /ɛ:/ phoneme could now be considered as part of the phonetic inventory of current BrE.
This question is of course not about phonemes but about the realization and notation of one particular phoneme (the SQUARE vowel).
Here’s what I replied.
I am of course well aware of the monophthongal variant of the SQUARE vowel. Please read what I wrote at http://www.phon.ucl.ac.uk/home/wells/ipa-english-uni.htm .
In LPD I took the decision to be conservative in phonetic notation for RP, sticking for example with Gimson's EPD symbols for the TRAP and GOAT vowels. Upton has made a different decision (including a very regrettable notation for the PRICE vowel).
I personally have a centring diphthong as my usual pronunciation of SQUARE in most phonetic positions. Perhaps that shows my age.
I shall not be changing the transcription in any future edition of LPD, but I agree I ought to insert a note to the effect that many people use a monophthongal quality. This, however, is not a new "phoneme", as you seem to believe. It is an alternative realization of an existing phoneme. There is no possibility of words being distinguished by the choice between the monophthongal and diphthongal variants of SQUARE.
Was I being too pedantic? If so, it’s what comes of a lifetime reading and commenting on students’ essays.
Anyhow, the take-home message is that monophthongal SQUARE is fine. But not obligatory.