Brain hearing activity. Coloured positron emission tomography (PET) scan data, showing brain activity (coloured) from hearing a known language. The PET data has been laid over three-dimensional magnetic resonance imaging (MRI) scans of profiles of the left (left) and right (right) brain hemispheres, positioned with the front of the brain at far left and right. The red and green areas of the temporal lobe of the brain are auditory areas. The yellow area (in the left temporal lobe) deals with known words. The pink area (in the left frontal lobe) is Broca's area, responsible for the production of speech. For a PET brain scan of the response to hearing an unknown language, see image P335/066.