Prosody, Information Structure, and Modality (Marianne Mithun - University of California, Santa Barbara)
There has been a tradition in linguistics of investigating grammatical structure by poring over isolated words, phrases, and sentences on a page. The tradition is understandable: before the mid-20th century it was nearly impossible to capture the sound of substantial stretches of spontaneous speech in natural, interactive settings. The written data did provide a foundation for understanding basic grammar. But technological advances in audio and video recording, acoustic analysis, and corpora and corpus software are now making it possible to investigate language in new ways. This paper demonstrates some ways in which adding considerations of prosody and discourse context can enhance our appreciation of certain structures and their functions.
One area of structure that continues to arouse interest is complex syntax. For some, the essence of syntactic complexity is the property of recursion, the occurrence of constituents within constituents of the same type. Prototypical recursive structures are complement constructions: John knows [that Mary left]. In their much-cited 2002 paper, Hauser, Chomsky, and Fitch propose that recursion is in fact universal to all human language, and the only property that distinguishes it from other communication systems. Everett (2005) has countered that recursion may not be a language universal after all.
A language that might appear to support Everett’s objection is Mohawk, indigenous to northeastern North America. Many Mohawk utterances that are translated into English complex sentences consist simply of sequences of finite clauses, each a grammatical sentence in itself. A passage translated ‘The government tried to displace us’, for example, was literally ‘the government tried; he would displace us’. Cristofaro has proposed that ‘subordination and non-subordination ... can be equated with (pragmatic) non-assertion and (pragmatic) assertion respectively’ (2003:30). If this is true, Mohawk would appear to be severely impoverished in its communicative capacity.
Yet there is more to linguistic structure than words on a page. Mohawk sequences of clauses like those above are usually integrated prosodically under a single intonation contour, which shows its own internal structure. The initial (matrix) clause begins on a high pitch then descends to a non-final fall. The following (subordinate) clause begins with a small pitch reset, but the whole is spoken with lower pitch and a narrower range of pitch variation, ultimately ending with a terminal fall. The prosodic structure thus appears to signal syntactic structure.
It could be that the lower pitch does not actually signal subordinate status; it might simply continue the overall declination pattern. But not all Mohawk sequences translated as complex sentences show declination. Sometimes what is translated as the complement is significantly higher in pitch than the preceding matrix. Interestingly, these are constructions in which the main information is conveyed by this prosodically more robust (complement) clause: ‘I think [you were away]’; ‘We heard [one woman was taken to the hospital]’; ‘Would it be possible [for you to say your name]?’. The initial, less prosodically-robust (matrix) clauses serve epistemic, deontic, evidential, evaluative, or interactional functions. The prosody conveys information structure that the syntax does not.
Prosody can also tell us more. It can provide glimpses of the dynamic development of grammatical structures over time. A number of modal constructions, for example, can be seen to have developed from complement constructions like those just described. With increased use, the matrix verbs take on more abstract modal meanings. Already prosodically weak, they are further reduced prosodically and segmentally. Patterns of interaction show that the erstwhile matrix verbs lose their salience as assertions and even as predications. At a certain point, they can cease to be anchored to their original sentence-initial position, sometimes taking on new text-structuring and interactional roles. The modern modal system mirrors this pathway of development nicely. A number of modal constructions at various stages of development now coexist in the modern language, many differentiated primarily by prosody.

Cristofaro, Sonia. 2003. Subordination. Oxford University Press.
Everett, Daniel 2005. Cultural constraints on grammar and cognition in Pirahã: Another look at the design features of human language. Current Anthropology 76.4:621-646.
Hauser, Marc, Noam Chomsky, and W. Tecumseh Fitch 2002. The faculty of language: What is it, who has it, and how did it evolve? Science 298:1569-1579.