Fig. 3

Schematic depiction of the dual speech coordination system model of Hickok and colleagues [85]. The laryngeal pitch control system is schematically represented via the upper curved purple arrow, and the supralaryngeal articulatory control system is schematically represented via the straight purple arrow (see text for details). The premotor dorsal precentral speech area involved in laryngeal pitch control is indicated by the upper dashed blue circle, above the dashed blue oval indicating the premotor ventral precentral speech area involved in the supralaryngeal articulatory control system. The dorsal laryngeal motor cortex and orofacial motor cortex are indicated by dashed orange ovals, with the location of the latter based on a meta-analysis from Guenther [96]. Frontal brain regions enclosed by white dashed lines and the brain system indicated by the curved purple arrow labelled “Morphosyntactic” are important for language and are discussed in Hickok et al. 2023 [85] but are not relevant to the current paper