Bantu-Ubangi language contact and the origin of labial-velar stops in Lingombe (Bantu, C41, DRC)

We examine the origin of labial-velar stops in Lingombe, a language from the northern Bantu borderland. Labial-velar stops are uncommon in Bantu. It is generally believed that they were acquired through contact with neighbouring non-Bantu speakers, in casu Ubangi languages. We show that the introduction of labial-velar stops in Lingombe is indeed a contact-induced change, but one which could not happen through superficial contact. It involved advanced bilingualism, whereby Ubangi speakers left a phonological substrate in the Bantu language to which they shifted. Once adopted, these loan phonemes underwent a further language-internal extension to native vocabulary, a process known as ‘hyperadaptation’. Both conventional sound symbolism and the deliberate attempt to differentiate the speech of one’s own social group were important for the further proliferation of labial-velar stops in Lingombe. This type of conscious analogical sound change is at odds with Neogrammarian principles of regular sound change.