Chapter 5 returns to the particular problems that Central Chadic languages pose for straightforward application of the comparative method, based on its peculiar typological features, mainly with regard to its underlying root-and-pattern structure, the effect of prosodies, and the interplay between phonemic and non-phonemic (epenthetic) surface vowels. These are exemplified with a focused comparative perspective on two very closely related languages, namely Lamang and Hdi, to follow the gradual divergence of modern surface forms from common underlying roots.

Chapter 6 presents full Proto-Central Chadic lexical reconstructions including both consonants and vowels. It discusses in detail alternative options for the reconstruction of different diachronic vowels from previous research. It presents systematic reconstructions that license the different surface vowels in modern languages, and adds some observations on the status and possible history of glottalisation in certain Central Chadic languages. In great detail, it presents full data and details of 64 lexical reconstructions.

Chapter 4 focuses on the actual diachronic processes affecting PCC reconstructions to yield surface representations in modern Central Chadic languages. Among these, in particular, processes of vowel epenthesis, the prosodic ‘colouring’ of both phonemic */a/ and pro- and epenthetic vowels, the syllabification of weak radicals (*/y/, */w/), and the occasional intersegmental fusion of features. It discusses the diachronic phonemicisation of allophones to yield the surface vowels of modern Central Chadic languages, and explains instances of the emergence of long vowels.

Chapter 1 introduces the reader to the research history of comparative Chadic linguistics and why it is so problematic to reconstruct lexical items for Proto-Chadic in general, and for Proto-Central Chadic in particular. It offers an abstract model for the evolution from Proto-Central Chadic ‘simple roots’ to phonetic surface representations in modern Central Chadic languages, based on root types that developed from a root-and-pattern structure inherited from Afroasiatic, but which recognises only one phonemic vowel */a/. It introduces synchronically petrified root-augmentative former grammatical elements on roots, which can and must be reconstructed. It discusses the eminent role of vowel pro-/epenthesis and the emergence and spread of both phonological and morphological prosodies from diachronic and underlying ‘weak radicals’ */y/ and */w/, and labialised consonants.

Chapter 3 introduces the templatic approach to Proto-Central Chadic phonology by identifying an underlying root-and-pattern structure with only one vowel phoneme available: */a/. It distinguishes diachronically simple and augmented roots (the latter carrying petrified former grammatical markers) and describes the high frequency of consonant metathesis. It discusses the inventory of PCC consonants and the double origin of prosodies, i.e. labialisation prosody and palatalisation prosody, plus occurrences of combined Y- and W-prosodies in the same word. It follows up on the different diachronic sources of morphological prosodies, and it takes an extra look at the occurrence of word-final schwa in place of final */a/. The chapter concludes with observations on the integration of loan words into the specific requirements of PCC phonology.

Chapter 2 deals with methodological preliminaries and introduces the central theoretical concepts. It begins by outlining the extra-linguistic historical background regarding the present habitat of Central Chadic languages. It identifies the exceptional typology of Central Chadic languages, in particular regarding their enigmatic vocalic domain. The chapter introduces the problems of applying the classic comparative method and explains the value of internal reconstruction. It discusses problems of dealing with various formats of data transcription, and it introduces central notions such as vowel epenthesis, weak radicals, vocalisation, and prosodies. Finally, it positions the current study against the background of previous studies on the subject.