Given these separate anatomical accounts, attributing a function(s) to the arcuate is not clear cut, and any current account is far from the authoritative statement on the matter. Nonetheless, a vast majority of literature does place the arcuate as part of the dual stream model of speech processing, although its exact role within these neural networks is still being disputed – and largely depends on which anatomical account you prescribe to.
The basic assumption of dual stream accounts is that phonological networks interact with both conceptual-semantic and motor-articulatory systems, leading to a distinction between the neural networks that process this speech information. These separate interactions are summarised under two processing streams: the dorsal stream and the ventral stream (Hickok and Poeppel, 2007). Connecting phonological networks with conceptual-semantic systems, using structures in the superior and middle portions of the temporal lobe, is the ventral stream. Meanwhile, the dorsal stream is linked via structures in the posterior frontal lobe to the posterior temporal lobe and parietal operculum, which connects phonological networks with motor-articulatory systems (ibid).