All four tonal oppositions occur only in certain frames, as for instance in a frame containing the tense marker ka 'future'. In the examples, there are four sound files which illustrate the four possible tone melodies associated with disyllabic nouns, namely HH, HL, LH, LL.
Grammatical tone is used for distinguishing nouns from verbs.
A different analysis of tone was proposed in Günther (1973) and in Traill & Ferraz (1981).
Source: Maurer 2009: 18-19
Source: Maurer 2009: 26
Source: Maurer 2009: 15
Source: Maurer 2009: 15
Source: Maurer 2009: 16
Source: Maurer 2009: 16
Source: Maurer 2009: 26