An exploration of the acoustic space of rhotics and laterals in Ruruuli

Liquid consonants—rhotics and laterals—have been shown to demonstrate unique distributional patterns cross-linguistically. It is also claimed that rhotics are more difficult to distinguish from one another phonetically than laterals, and that rhotics are less flexible than laterals when it comes to participation in consonant clusters and coarticulatory patterns. We investigate the phonetic realization of the rhotic and lateral phonemes in a Bantu language, Ruruuli. The acoustic space used for rhotics and laterals in this language is extremely similar, although the density peaks in terms of formant values are different. Formant values as well as formant ratios can be reliably used to distinguish between rhotics and laterals. In common with many other languages, an asymmetry between laterals and rhotics is found in Ruruuli, with laterals being more positionally constrained than rhotics. The overlap in acoustic space between rhotics and laterals may cast doubt on the status or stability of the phonological contrast between rhotics and laterals in this language.