The case for alveolar fricative rhotics with evidence from Nusu

Cross-linguistically, fricatives are the rarest types of rhotics, found in a few African and European languages ( Ladefoged & Maddieson 1996 ) and as allophones in some Romance languages ( Jesus & Shadle 2005 ; Recasens 2002 ; Bradley 2006 ; Colantoni 2006 ). Acoustic data from Nusu, phonotactic reasoning, and a cognate comparison demonstrate the presence of alveolar fricative rhotics in Tibeto-Burman. The Nusu rhotic appears in syllable-initial position as the first or second consonant and can be realized as alveolar approximants [ɹ] or [ɹʲ], non-sibilant voiced and voiceless fricatives [ɹ, ɹ], as well as voiced sibilant [ʐ]. In other studies on Nusu, these fricative rhotics have sometimes been reported as retroflex voiced sibilants ( Sun & Lu 1986 ; Fu 1991 ), but intra-speaker and cross-variety comparison point to classification as rhotics. Evidence from other Tibeto-Burman languages suggests that alveolar fricative rhotics are not limited to Nusu. Together these data challenge the tradition of generally interpreting alveolar fricatives as sibilants.