Key: the brain tracks how many times a specific note is sounded, its length, and where it appears relative to other notes. Networks of neurons form abstract representations of musical structure and rules to identify the key.
Pitch: causes eardrum to vibrate at the same frequency. The vibration is analyzed by the inner ear and brain to determine the eardrum vibration, which is represented directly on the auditory cortex.
Harmony: Many vibrations related to one another as integer multiples occur on the eardrums simultaneously. They trigger synchronous neural firings in the auditory cortex.
Listening to music: Listening begins at the subcortical level in the cochlear nuclei, brain stem, and cerebellum. It progresses to the auditory cortex in both R and L hemispheres. Familiar music involves the hippocampus, cerebellum, and inferior frontal cortex of the frontal lobes.
Playing a musical instrument: With learning, the coordination becomes smooth and semi-conscious. This coordination involves the cerebellum and brainstem, plus the motor cortex of the parietal lobes and planning regions of the frontal lobes. (Sternberg, Barbara, PhD. Music & the Brain. p 7-9. CA: Institute for Natural Resources, Home-Study #2320, 2009).