An Acoustic Study of Sandhi Vowel Hiatus in Luganda

In Luganda (Bantu, Uganda), a sequence of vowels in successive syllables (V.V) is not allowed. If the first vowel is high, the two vowels are joined together in a diphthong (e.g., i + a → i͜a). If the first vowel is non-high, it is deleted with compensatory lengthening of the second vowel in the sequence (e.g., e + a → aː). This paper presents an acoustic investigation of inter-word V#V sequences in Luganda. It was found that the vowel interval in V#V sequences is longer than that in V#C sequences. When the first vowel in V#V is non-high, the formant frequency of the outcome is determined by the second vowel in the sequence. When the first vowel is high, on the other hand, the sequence is realized as a diphthong, with the transition between the two formant patterns taking up most of the duration. The durational patterns within these diphthongs provide evidence against the transcription-based claim that these sequences are reorganized so that the length lies in the second vowel (/i#V/ → [jVː]). The findings bring into question a canonical case of compensatory lengthening conditioned by glide formation.