A featural analysis of mid and downstepped high tone in Babanki

In this study, I examine the occurrence of the surface Mid (M) and downstepped
High (↓H) tone in Babanki, a Central Ring Grassfields Bantu language of Cameroon.
Hyman (1979) has demonstrated that Babanki has two underlying tones, namely,
High (H) and Low (L), and that on the surface, it contrasts three level tones, H, M,
L, plus a downstepped High (↓H). There is also contrast between a falling (L) and a
level low (Lo) tone before pause in the language. I demonstrate in this paper that the
M tone is from two different phonological sources and derived by the regressive
spread of the high register feature of a following H tone while ↓H is caused by
the progressive spread of the low register feature of a preceding floating L tone.
The M and ↓H tone are phonetically identical in the language but differ in that ↓H
establishes a ceiling for following H tones within the same tonal phrase.