Notes:The orthography used in this and related articles is that of South Africa, not Lesotho. For a discussion of the differences between the two see the notes on Sesotho orthography.

The phonology of Sesotho and those of the other Sotho–Tswana languages are radically different from those of "older" or more "stereotypical" Bantu languages. Modern Sesotho in particular has very mixed origins (due to the influence of Difaqane refugees) inheriting many words and idioms from non-Sotho–Tswana languages.

There are in total 39 consonantal phonemesOther authors may choose to include the labialized consonants as contrastive phonemes, potentially increasing the number by 26 to 75. Labialization does create minimal pairs, as is exemplified by the short passive suffix, but different authors seem to be divided on whether or not these should be counted as authentic phonemes (especially since Sotho–Tswana-type labialization caused by vowel "absorption" is a fairly strange and rare process).

Besides the passives, there are still numerous minimal pairs differing only in the labialization of a single consonant (note that each of the following pairs has similar tonal patterns): -rala ('design'), versus -rwala ('carry on the head') -lala ('lie down' [old fashioned or poetic]), versus -lwala ('be sick' [old fashioned]) mora ('son'), versus morwa ('a Khoisan person') -hama ('milk an animal'), versus -hwama ('[of fat] congeal') -tshasa ('smear'), versus -tshwasa ('capture prey') mohla ('day'), versus mohlwa ('termite')

Normal consonants and their labialised forms do not contrast before back vowels (that is, a labialized consonant will lose its labialization before a back vowel). (plus 2 allophones) and 9 vowel phonemes (plus two close raised allophones). The consonants include a rich set of affricates and palatal and postalveolar consonants, as well as three click consonants.

Historical sound changes Probably the most radical sound innovation in the Sotho–Tswana languages is that the Proto-Bantu prenasalized consonants have become simple stops and affricates.The Sotho–Tswana ejective stops , , and come from the Proto-Bantu *mb, *nd, and *ŋg due to the radical effects of the nasalization process. The Proto-Bantu stops *p, *t, and *k have usually become , , and ( and in modern Sesotho) with *kû becoming , and the nasalized forms of these (Proto-Bantu *mp, *nt, and *ŋk) are the two aspirated stops and , and the aspirated velar affricate ( in most Sesotho speaking communities).

Note that some Sotho–Tswana languages do have prenasalized consonants, or at least have less strict and varied nasalization rules, but this is almost certainly as a result of influence from neighbouring non-Sotho–Tswana languages. Thus isiZulu words such as entabeni ('on the mountain'), impuphu ('flour'), ezinkulu ('the big ones'), ukulanda ('to fetch'), ukulamba ('to become hungry'), and ukuthenga ('to buy') are cognates to Sesotho thabeng, phofo, tse kgolo, ho lata, ho lapa, and ho reka, respectively (with the same meanings).

This is further intensified by the law of nasalization and nasal homogeneity, making derived and imported words have syllabic nasals followed by homogeneous consonants, instead of prenasalized consonants.

Another important sound change in Sesotho which distinguishes it from almost all other Sotho–Tswana languages and dialects is the chain shift from and to and (the shift of to is not yet complete).

In certain respects, however, Sesotho is more conservative than other Sotho–Tswana languages. For example, the language still retains the difference in pronunciation between , , and .Strictly speaking, should be an allophone of found only when is nasalized. However, possibly due to the mixed origins of Sesotho, there are several instances of appearing without nasalization (as is the case in Setswana) or of failing to nasalize when the nasalizing consonant is not visible (such as when forming polysyllabic class 9 nouns).

Thus one finds: ho hlaha ('to emerge') > class 9 tlhaho ('nature') ho hlompha ('to respect') > class 9 hlompho ('respect') where the nasalization is applied in the first noun but not the second. Many other Sotho–Tswana languages have lost the fricative , and some Northern Sotho languages, possibly influenced by Tshivenda, have also lost the lateral affricate and pronounce all three historical consonants as (they have also lost the distinction between and — thus, for example, speakers of the Northern Sotho language commonly called Setlokwa call their language "Setokwa").A further collapse occurred in Silozi — which has lost the generally unusual distinction between plain and aspirated consonants. Thus Sesotho , , , , and all map to the single Silozi phoneme .

The existence of (lightly) ejective consonants (all unvoiced unaspirated stops) is very strange for a Bantu language and is thought to be due to Khoisan influence. These consonants occur in the Sotho–Tswana and Nguni languages (being over four times more common in Southern Africa than anywhere else in the world), and the ejective quality is strongest in isiXhosa, which has been greatly influenced by Khoisan phonology.

As with most other Bantu languages, almost all palatal and postalveolar consonants are due to some form of palatalization or other related phenomena which result from a (usually palatal) approximant or vowel being "absorbed" into another consonant (with a possible subsequent nasalization).

The Southern Bantu languages have lost the Bantu distinction between long and short vowels. In Sesotho the long vowels have simply been shortened without any other effects on the syllables; while sequences of two dissimilar vowels have usually resulted in the first vowel being "absorbed" into the preceding consonant, and causing changes such as labialization and palatalization.

As with most Southern African Bantu languages, the "composite" or "secondary" vowels *e and *o have become and . These usually behave as two phonemes (conditioned by vowel harmony), although there are enough exceptions to justify the claim that they have become four separate phonemes in the Sotho–Tswana languages.

Additionally, the first-degree (or "superclose", "heavy") and second-degree vowels have not merged as in many other Bantu languages, resulting in a total of 9 phonemic vowels.

Almost uniquely among the Sotho–Tswana languages, Sesotho has adopted clicks.Urban varieties of Pedi are currently acquiring clicks as well. There is one place of articulation, alveolar, and three manners and phonations: tenuis, aspirated, and nasalized. These most probably came with loanwords from the Khoisan and Nguni languages, though they also exist in various words which don't exist in these languages and in various ideophones.

These clicks also appear in environments which are rare or non-existent in the Nguni and Khoisan languages, such as a syllabic nasal followed by a nasalized click ( written , as in nnqane 'that other side'), a syllabic nasal followed by a tenuis click (, also written , as in senqanqane 'frog'; this is not the same as the prenasalized radical click written in the Nguni languages), and a syllabic nasal followed by an aspirated click ( written , as in seqhenqha 'hunk').

Vowels

Sesotho has a large inventory of vowels compared with many other Bantu languages. However, the nine phonemic vowels are collapsed into only five letters in the Sesotho orthography. The two close vowels i and u (sometimes called "superclose" or "first-degree" by Bantuists) are very high (with advanced tongue root) and are better approximated by French vowels than English vowels. That is especially true for , which, in English, is often noticeably more fronted and can be transcribed as or in the IPA; which is absent from Sesotho (and French).

+ Vowels‡The IPA symbols used for the near-close vowels in this and related articles are different from those that are often used in the literature. Often, the symbols and are used instead of the standard and , but they represent the close central unrounded vowel and the close central rounded vowel, respectively, in modern IPA. ho bitsa ('to call') beet tumo ('fame') boot ho leka ('to attempt') pit potso ('query') put ho jwetsa ('to tell') cafe pontsho ('proof') yawn (RP, SAE) ho sheba ('to look') bed mongolo ('writing') board ho abela ('to distribute') spa

Consonants The Sotho–Tswana languages are peculiar among the Bantu family in that most do not have any prenasalized consonants and have a rather-large number of heterorganic compounds. Sesotho, uniquely among the recognised and standardised Sotho–Tswana languages, also has click consonants, which were acquired from Khoisan and Nguni languages.

LabialAlveolarPost-alveolarPalatalVelarUvularGlottalmedianlateralClickglottalized aspirated nasal Nasal Stopejective aspirated voiced()1 Affricateejective aspirated ~ Fricativevoiceless ~ voiced ~ Approximant Trill r

is an allophone of , occurring only before the close vowels ( and ). Dialectical evidence shows that in the Sotho–Tswana languages was originally pronounced as a retroflex flap before the two close vowels.

Sesotho makes a three-way distinction between lightly ejective, aspirated and voiced stops in several places of articulation.

+ Stops‡Place of articulationIPANotesOrthographyExamplebilabialunaspirated: spitp pitsa ('cooking pot') ph phuputso ('investigation')this consonant is fully voicedb lebese ('milk')alveolarunaspirated: stalkt botala ('greenness') th tharollo ('solution')an allophone of , only occurring before the close vowels ( and )d Modimo ('God')velarunaspirated: skillk boikarabelo ('responsibility')fully aspirated: kill; occurring mostly in old loanwords from Nguni languages and in ideophoneskh lekhokho ('pap baked onto the pot')

Sesotho possesses four simple nasal consonants. All of these can be syllabic and the syllabic velar nasal may also appear at the end of words.

+ Nasals‡Place of articulationIPANotesOrthographyExamplebilabial m ho mamaretsa ('to glue')syllabic version of the abovem mpa ('stomach')alveolar n lenaneo ('programme')syllabic version of the aboven nna ('I')alveolo-palatala bit like Spanish el niñony ho nyala ('to marry')syllabic version of the aboven nnyeo ('so-and-so')velar can occur initiallyng lengolo ('letter')syllabic version of the aboven ho nka ('to take')

The following approximants occur. All instances of and most probably come from original close , , , and vowels or Proto-Bantu *u, *i, *û, and *î (under certain circumstances).

Note that when appears as part of a syllable onset this actually indicates that the consonant is labialized.

+ Approximants‡Place of articulationIPANotesOrthographyExamplelabial-velar w sewa ('epidemic')lateral never occurs before close vowels ( and ), where it becomes l selepe ('axe')a syllabic version of the above; note that if the sequence is followed by the close or then the second is pronounced normally, not as a l mollo ('fire')palatal y ho tsamaya ('to walk')

The following fricatives occur. The glottal fricative is often voiced between vowels, making it barely noticeable.There are many historical instances in Sesotho which show an occasional confusion between the phonemes , , and (no consonant). For example, the verb -aha ('build') often appears as -haha (cf. Silozi -yaha), though comparison with other languages (Setswana -aga, Nguni -akha, etc.) reveals its true form.