Vowels and diphthongs BATH, PALM
The phonetic qualities of the BATH and PALM vowels depend on their phonetic environments, and vary in different areas and localities. The exact phonetic quality and distribution of the Southwestern variants is not fully understood. Wells (1982: 345–346) and Hughes and Trudgill (1996: 57) suggest the following description:
(1) In the standard lexical set of BATH, two vowels are possible: (a) [a’] and (b) [æ :]. In those accents which have BATH [a’] and (lengthened) TRAP [a’], phonemic contrast is absent or variable. However, neither TRAP [a’] nor the TRAP-BATH merger are categorical. According to Wells (1982: 346), Bristol and Southampton, for instance, retain an opposition between TRAP and BATH as in “gas [gæs] vs. grass [græ:s ~ gra:s]”.
(2) The situation becomes yet more complex when we consider the vowel of the lexical set PALM. Wells (1982: 346) suggests the following rule of thumb: If historical /l/ in words such as palm and calm is retained, which is the case in some parts of the Southwest, the vowel is probably a back unrounded [a], such that palm is pronounced as 
. PALM words without historical /l/, such as father, bra, spa, tomato, banana, etc., have the same vowel as that found in BATH items.
FACE and GOAT Traditional rural accents in Devon and Cornwall have the monophthongal FACE and GOAT variants [e:] and [o:]. Wakelin also reports some instances of centring and opening diphthongs (e.g. 
) which appear to be rather like those used in north-eastern England. These pronunciations and the close-mid monophthongs [e:] and [o:] are, however, recessive and appear to be giving way to (closing) diphthongal variants resembling those used in South-eastern England. Such diphthongal variants have fairly open starting points in the vicinity of [ə] and 
.
