The influence of language familiarity on voice discrimination: Divergent and shared neural mechanisms

Language familiarity significantly modulates speaker discrimination, with listeners demonstrating superior performance for familiar versus unfamiliar languages. To address the confound of speech content acoustics in prior research, this fMRI study investigated the cognitive and neural mechanisms underlying this effect using identical speech content across three languages of varying listener proficiency. Behaviorally, familiar language discrimination elicited faster responses and higher accuracy. Neurally, bilateral insula and anterior cingulate cortex activation during different-speaker trials intensified as language familiarity decreased. The left rostrolateral prefrontal cortex was specifically engaged for unfamiliar voice discrimination and sensitive to speaker identity. Conjunction and representational similarity analyses across languages revealed engagement of voice-selective, cognitive control, and semantic processing regions, with high cross-language neural representational similarity specifically localized to the right dorsolateral prefrontal cortex and left inferior frontal gyrus. These findings provide the evidence under speech-content-matched conditions demonstrating that speaker discrimination relies on both acoustic voice processing regions and cognitive control networks implementing top-down modulation, the intensity of which is inversely proportional to language familiarity level.