A number of studies have argued that prosodic structure is closely related to syntactic structure, yet few empirical investigations have been made on how phonetic measurements vary as a function of syntax. In addition, we do not know how the interaction between syntax and prosody varies by different speech rate

The current study investigates the prosodic structure of the two types of English relative clauses, non-restrictive relative clauses (NRRC) and restrictive relative clauses (RRC). These structures were read at varying rates which were elicited using a visual analogue rate cue.

The results showed that there are articulatory and acoustic differences between productions of NRRCs and RRCs. Furthermore, the prosodic difference between the two RCs interacted with speech rate such that most of the phonetic measures associated with two structures were neutralized at fast speech rates.