ISCA Tutorial and Research Workshop on Experimental Linguistics (ExLing 2008)
Traditionally, parentheses have been described by phoneticians as speech segments with lower intensity, restrained pitch variation and speech rate faster than the rest of the sentence. This iconic coding may be found in some examples of read (prepared) speech, but spontaneous speech data tend to show that specific prosodic mechanisms do exist to either 1) integrate the syntactic parenthesis into the overall prosodic structure of the sentence or 2) isolate it with an independent prosodic structure. The realizations chosen by speakers appear to be dictated by the interaction of semantic, syntactic and prosodic markers to ensure the parentheses will be identified as such by listeners.
Bibliographic reference. Martin, Philippe (2008): "Intonation of parentheses in spontaneous French sentences", In ExLing-2008, 157-160.