Neuron 65, 852–858 (2010)

Infants just seven months old have a specialized sensitivity to the human voice and its emotional content that is similar to that of adults.

Tobias Grossmann at Birkbeck, University of London, and his colleagues used near-infrared spectroscopy to monitor the activity of different brain areas in four- and seven-month-old babies as they listened to various recorded voices and sounds.

Compared with other sounds, the researchers found increased responses to the sound of a human voice in the right and left superior temporal cortex by the age of seven months. They saw a greater response in a voice-sensitive region of the right hemisphere when the voice conveyed anger or happiness. Happy emotion also activated the right inferior frontal cortex — an effect that has been seen in adults. This sensitivity to voice and emotion is thought to be crucial for social communication.