Phonetic implementation of high-tone spans in Luganda

In Luganda, a Bantu language of Uganda, there are long high-tone spans, which include multiple syllables, as well as short high-tone spans, limited to a single syllable. Long high-tone spans result from unbounded leftward spread of either lexical high tones or an intonational high boundary tone. This study investigates whether long tone spans in Luganda differ phonetically in f0 timing or scaling from short tone spans, and whether lexical high tones are implemented differently than intonational ones. In a production study involving 10 Luganda speakers, it was found that the initial f0 rise ends significantly later in long high-tone spans than in short high-tone spans, reflecting the reduced time pressures involved when the f0 rise is in a separate syllable than the f0 fall. The final f0 fall at the end of the span begins earlier in the syllable in long high-tone spans than in short high-tone spans, reflecting the same time pressures. There was no difference in f0 level between long and short high-tone spans, indicating that the time pressure does not lead to undershoot. The intonational high tone has significantly smaller f0 excursions in the initial rise and the final fall, compared to the lexical high tones.