The two main phonological features that mark South African English as distinct are the behaviour of the vowels in KIT and PALM. The KIT vowel tends to be "split" so that there is a clear allophonic variation between the front [ɪ] and central [ɪ̈] or [ə]. The PALM vowel is characteristically back in the General and Broad varieties of SAE. The tendency to monophthongise/aɤ/ and /aɪ/ to [ɑː] and [aː] respectively, are also typical features of General and Broad White South African English.
General South African English features phonemic vowel length (so that ferry/ˈferiː/ and fairy/ˈfeːriː/ differ only in length) as well as phonemic roundedness, so that fairy/ˈfeːriː/ is distinguished from furry/ˈføːriː/ by roundedness.
Features involving consonants include the tendency for /tj/ (as in tune) and /dj/ (as in dune) to be realised as [tʃ] and [dʒ], respectively (See Yod coalescence), and /h/ has a strong tendency to be voiced initially.
/iː/ is a long close front monophthong [iː], either close to cardinal [iː] or slightly mid-centralised. It does not have a tendency to diphthongise, which distinguishes SAE from Australian and New Zealand English.
The HAPPY vowel is phonemically equal to /iː/ in General and Broad and to /ɪ/ in Cultivated. Thus, happy and immediately are phonemically /ˈhæpiː/ and /əˈmiːdiːətliː/ in General and Broad and /ˈhæpɪ, ɪˈmiːdɪətlɪ/ in Cultivated. The pronunciation with FLEECE is sometimes considered to bare secondary stress, so that happy can be analysed as /ˈhæpˌiː/.
/ɵ/ is typically a weakly rounded retracted central vowel [ɵ̠], somewhat more central than the traditional RP value. Younger speakers of the General variety (especially females) often use a fully central [ɵ]. Backer and sometimes more rounded variants ([ʊ ~ ʊ̹]) occur before [ɫ]. Broad SAE can feature a more rounded vowel, but that is more common in Afrikaans English.
/ʉː/ is usually central [ʉː] or somewhat fronter in White varieties, though in the Cultivated variety, it is closer to [uː] (typically not fully back, thus [u̟ː]), which is also the normal realisation before [ɫ] in other varieties. Younger (particularly female) speakers of the General variety use an even more front vowel [yː], so that food[fyːd] may be distinguished from feed[fiːd] only by rounding. The vowel is often a monophthong, but there is some tendency to diphthongise it before sonorants (as in wounded[ˈwʉundəd] and school[skʉuɫ]).
/e/ is close-mid [e] or higher [e̝] in General, often with centralisation [ë ~ ë̝]. Closer variants are typical of female speech. General /e/ is similar enough to /ɪ/ in RP and similar accents as to cause perceptual problems for outsiders. Broad variants are very similar to the General ones, but in Cultivated the vowel can be as open as [e̞] (within the RP norm). In General and Broad, the vowel can be lowered to [ɛ] or even [æ] when it occurs before [ɫ].
/eː/ is realised as a centring diphthong [ɛə] in the Cultivated variety. The broad realisation is a monophthong, close-mid [eː] or higher [e̝ː] (but not as close as to merge with /iː/). In General the vowel is often a close-mid monophthong (especially for younger speakers), but it can also be open-mid [ɛː] or the Cultivated variant [ɛə]. Monophthongal realisations are often stigmatised by General speakers, even those who diphthongise. When realised as [eː], /eː/ can be considered to be the long counterpart of /e/ as there is almost no difference in quality between the two.
In General and Broad, /øː/ is a rounded front vowel that varies between close-mid [øː] and open-mid [œː], with the former being more usual. In Cultivated an unrounded, RP-like mid central [ɜː] is used, with a more open [ɐː] being a possible alternative, though the latter could also be thought of as a hypercorrection.
In Cultivated, final /ə/ is sometimes more open than in other varieties ([ɐ] or even [ä]), so that comma can be pronounced [ˈkɒmɐ] or [ˈkɒmä] instead of the more usual [ˈkɒmə].
/oː/ is close-mid [oː], as in Australian and New Zealand English. A somewhat more open realisation [o̞ː] is possible in the General variety and usual in Cultivated SAE.
In Cultivated and General, /æ/ is realised as [æ] or somewhat closer ([æ̝]). However, the new prestige value in younger Johannesburg speakers of the General variety (particularly those who live in the wealthy northern suburbs) seems to be open front [a], the same as in Modern RP. Before [ɫ], the fully open [a] is the norm in the General variety, whereas before voiced stops and nasals (except the velar /ŋ/) the vowel tends to be centralised and lengthened to [æ̈ː], often with slight diphthongisation ([æ̈ːə]). Broad /æ/ can be as close as mid [ɛ̝], encroaching on the Cultivated realisation of /e/.
/ɐ/ is normally an open vowel, either central [ɐ̞] or retracted front [a̠], although younger, especially female speakers of the General variety may realise this vowel as close and front as open-mid centralised front [ɛ̈].
/ɒ/ is realised as a mid-centralised cardinal [ɒ] with very weak rounding ([ɒ̜̽]), or sometimes unrounded [ɑ̽]. The unrounded variant can be raised to open-mid [ʌ̈], especially when it occurs in non-prominent syllables. The unrounded open-mid variant is gaining ground among General speakers in Cape Town and Natal, who generalise it to other positions (so that lot becomes [lʌt] instead of the traditional [lɒt ~ lɑt]). There have been no reports of LOT merging with STRUT.
In General, /ɑː/ is an open back unrounded vowel [ɑː], either fully back (as in Broad) or slightly more front. The broad variants can be rounded [ɒː], sometimes with raising to [ɔː] and/or shortening to [ɒ] or [ɔ], so that Broad dark[dɒk] can encroach on General and Cultivated dock[dɒk], or at least be differentiated from the latter by length. Weak rounding of this vowel is now somewhat less stigmatised than it was in the 20th century. In Cultivated, a categorically unrounded advanced back [ɑ̟ː] or (more rarely) central [äː] is used.
The KIT split
In General and Broad, this vowel is split between a more front realisation ([ɪ] in General, [i] in Broad) and a more central realisation ([ɪ̈] in General, [ɪ̈] or [ə] in Broad). More front variants are used in contact with velar and palatal consonants, whereas more central realisations are used in other environments (and therefore are more common), with an even more retracted [ɯ̽] being possible before the velarised allophone of /l/, so that pill (phonemically /pəl/) can be realised as [pɯ̽ɫ], close to pull[pʊɫ]. The Cultivated variety lacks this split, and uses a lax front [ɪ] in every position.
John Wells analyses the front variants as /ɪ/ and the central variants as /ə/, which makes /ə/ one of the stressable vowels in South African English. Some scholars prefer to analyse all of the variants as allophones of /ɪ/. This article adopts the former approach, even though the split does not create any minimal pairs.
/eɪ/ is realised as [eɪ] in General and Cultivated. In General, more open onsets [ɛɪ ~ æɪ] are possible in accents closer to Broad SAE. However, in Broad SAE, the first element is actually back [ʌɪ].
/aɪ/ is a diphthong [aɪ] in Cultivated. In General and Broad, it is more often a monophthong [aː], with a diphthong with a retracted onset [ɑ̽ɪ] also possible in Broad.
/ɔɪ/ is realised as [ɔɪ] in all White varieties. In the Cultivated variety, the first element may be lowered to [ɒ].
/œɨ/ regularly has a rather front onset in Cultivated and General varieties. In Cultivated, it is realised as [ɛʊ ~ œʊ], with the former being more common. In General, the onset is always rounded, and the offset is central [œʉ ~ œɨ̞], with a tendency to monophthongise it to [œː]. The Broad realisation is back [ʌʊ].
/aɤ/ is realised as [ɑ̈ʊ] in Cultivated, [ɑː] in General and [æʊ] in Broad.
/ɪə/ is realised as [ɪə] in White varieties, but Broad speakers tend to monophthongise it to [ɪː], especially after /j/.
/ʉə/ is a glide from [ɵ̠] to [ə] in the Cultivated variety, whereas in Broad it is monophthongised to [oː]. The General variety varies between these two, with a growing tendency to use the monophthong [oː] (the same as the THOUGHT vowel or somewhat lower), especially when /j/ doesn't precede.