Tone and contours is the focus of this lecture. Tone is a property based on the contrastive use of pitch. Rising is low followed by high tones. Level of tone above level of segment, attached by line. An operation on one tier does not mean there is an operation on another tier. Ex. if a segment is deleted, the tone is not necessarily deleted it can stay or go. If delete vowel, tone remains on its own tier. Oke okpa the e is deleted, but its high tone combines with the following o"s low tone: falling contour results. Twin sister convention when have combination of identical tones, get only one tone, no contour. High tone of noun becomes low tone when prefixed. Tone occurring occurs to the vowel adjacent to the prefix: but in cases where vowels farther away are also affected, it means that the tones for those vowels are branched.