The acoustics of strengthened glides in Kirundi

Strengthening of post-consonantal glides /w/ and /j/ to obstruents or nasals is cross-linguistically uncommon, especially when the process is synchronically conditioned. This study investigates acoustic correlates of post-consonantal glide strengthening in Kirundi, an eastern Bantu language spoken in Burundi. The materials included words with /w/ or /j/ preceded by labial obstruent or nasal consonants /p, b, v, m/—the contexts that have been previously described to trigger the process. The morphological context was also varied, with sequences occurring at prefix-root or suffix-root boundaries, or within a root. Four female and four male native speakers produced the word list in a carrier sentence three times. The analysis involved phonetic classification of strengthened glides, as well as their duration and spectral measurements (frication/burst spectra and following vowel formants). The results showed that the post-consonantal /w/ was consistently realized as an oral or nasal stop agreeing with the preceding consonant in voicing and nasality, consistently with previous descriptive accounts. The realization of the post-consonantal /j/, however, was considerably more variable across and within speakers, ranging from a palatal stop or nasal to a weakly fricated/nasalized glide, and showing some sensitivity to morphological structure.