A team of researchers in Belgium used functional magnetic resonance imaging (fMRI) to measure brain activity in 14 participants while they performed a task in which they recognised previously learned faces, voices, and voice-face associations. Dr Frederic Joassin, Dr Salvatore Campanella, and colleagues compared the brain areas activated when recognising people using information from only their faces (visual areas), or only their voices (auditory areas), to those activated when using the combined information. They found that voice-face recognition activated specific "cross-modal" regions of the brain, located in areas known as the left angular gyrus and the right hippocampus. Further analysis also confirmed that the right hippocampus was connected to the separate visual and auditory areas of the brain.
Recognising a person from the combined information of their face and voice therefore relies not only on the same brain networks involved in using only visual or only auditory information, but also on brain regions associated with attention (left angular gyrus) and memory (hippocampus). According to the authors, the findings support a dynamic vision of cross-modal interactions in which the areas involved in processing both face and voice information are not simply the final stage of a hierarchical model, but rather, they may work in parallel and influence each other.
The article is "Cross-modal interactions between human faces and voices involved in person recognition" by Frederic Joassin, Mauro Pesenti, Pierre Maurage, Emilie Verreckt, Raymond Bruyer, Salvatore Campanella, and appears in Cortex, Volume 47, Issue 3 (March 2011), published by Elsevier in Italy.