Abstract: While prosodic structure largely corresponds to syntactic structure, prosody is often found to be 'flatter' than syntax. Most research addressing apparent exceptions to syntax-prosody isomorphism utilizes one of two strategies: i) pursue sentence-level phonological well-formedness explanations, i.e., a phonological solution, or ii) propose an underlying syntax that matches the surface prosodic form, i.e. a syntactic solution. In this talk, I discuss a syntax-prosody mismatch in Rutooro, (first discussed in Bickmore and Clemens 2019), that defies both the strictly syntactic and prosodic explanations, arguing instead for a syntax-prosody interface solution. In Rutooro, a Bantu language of Uganda, phonological prominence is marked with a High tone (H) on the penultimate syllable of the phonological phrase (φ-phrase). Like many languages in the family, syntactic XPs reliably correspond to φ-phrases. However, reduced object RCs with overt subjects are a special case: the head of the reduced object RC bears an unexpected H tone, while the subject is all-Low despite the fact that it is a self-contained XP.
I argue that the attested, non-isomorphic phrasing prevents an indeterminate prosodic structure from surfacing that, while predicted by the syntax and resolvable by the morphology, would result in the violation of the otherwise reliable correspondence between syntactic and prosodic constituents in the language. Thus, while the prosodic realization of one specific construction in the language is exceptional, this exception allows for greater regularity in the signaling of syntactic constituency via prosodic structure.