Rhodes linguist Will Bennett has discovered a sound change in some varieties of Setswana that seems to go against a trend found in languages around the world: in Setswana, the sound ‘s’ changes to ‘sh’ before back vowels like ‘o’. He described this change in a very interesting Departmental Research Seminar on Tuesday 25 October 2016.
The process of ‘s’ changing to ‘sh’ is an example of palatalization, a well-known and widespread phonological phenomenon in which sounds which were produced at other places of articulation shift towards the palate. Palatalization usually happens before a front vowel such as the ‘i’ sound in ‘sushi’. In Setswana, a very different pattern of palatalization occurs: sounds like ‘s’ change to ‘sh’ before back vowels like ‘o’ and ‘w’. Here are some examples:
- -hisa (burn) becomes sihisho (burner)
- -omisa (dry) becomes siwomisho (dryer)
- -bontsa (show) becomes pontsho (showing)
Palatalization before back vowels seems unnatural to phonologists, but there seem to be plenty of examples of it in Setswana. How can this be? Will suggests that this pattern is a result of the fact that speakers round their lips to pronounce back vowels in Setswana, as in many other languages. It is also a common thing for speakers to round their lips when pronouncing ‘sh’ to make it sound more distinct from ‘s’. So, if people started rounding their lips early before pronouncing a back vowel, then the ‘s’ in words like those above would start to sound more like ‘sh’, leading to palatalization before these back vowels and ‘w’, which is also pronounced with rounded lips.