26 This book also devotes an entire chapter to the typological tonal characteristics of three
major geographical areas: Africa, AsiaPacific, and Central America. Meanwhile, Bao 1999 focuses almost exclusively on Chinese languages and Snider 1999 focuses
almost exclusively on African languages.
3.3 Snider 1999
Snider 1999 proposes a specific model of tonal features and geometry which he calls Register Tier Theory RTT and then applies it to case studies of four languages.
This book focuses almost exclusively on African languages. While Snider does not give detailed analyses of processes common to Asian languages copying of contours, etc.,
his brief explanation 55-57 of the types of possible contour tones in RTT seems to allow for an analysis very similar to that of Bao 1999.
RTT, as discussed in Snider 1 i very ꜛuch iꜜ the pirit of leꜛeꜜt 1 83
aꜜd Hyꜛaꜜ 1 85, 1 86” 23. RTT eꜛploy two tonal features: register and tone. The
register feature
i defiꜜed a pecifyiꜜg] whether the regi ter of a giveꜜ] T U i higher h or lower l thaꜜ the precediꜜg regi ter” 25. Therefore, regi ter i alway
relative to a precediꜜg regi ter, a fuꜜdaꜛeꜜtal differeꜜce betweeꜜ RTT’ regi ter feature and the register feature of models like those described in Bao 1999 and Yip 2002.
Tone in RTT specifies whether a given TBU is pronounced at a high H or low L pitch
relative to its register. These two features allow for up to four pitch levels following any given tone, as shown below, where the dashed lines represent register and the short bars
abovebelow an arrow represent the actual pronounced pitch:
27
7
Realization of register and tone features Snider 1999:25:
The geometry of these features is as follows. Tone and register each have their own tier, and each is associated to a single Tonal Root Node TRN tier, which in turn is
associated to the tonal-bearing unit tier. This can be represented schematically as follows:
8
RTT feature geometry:
Snider refers to the four possible phonemic tones as Hi H tone,
h
register, Mid
1
H tone,
l
register, Mid
2
L tone,
h
register, and Lo L tone,
l
register. The main strength of the RTT model of tonal geometry is the way in which it
handles downstep, which will be discussed further in §3.5. The detailed case studies of downstep and upstep in chapters 4-7 of Snider 1999 are also extremely helpful to those
studying or analyzing other languages with these processes. It would be desirable to also do similar case studies in Asian languages to be able to better evaluate RTT as a universal
theory of tone.
28 Having completed our survey of three important proposals for tone structure, we
now turn to various theoretical approaches to three tonal processes: spreading, downstep, and upstep.
3.4 Tone spreading
