The most pleasing musical chords have simple mathematical relationships between the different sound frequencies within them, but the source of this perception is mysterious. A recent mathematical model suggests that the key may be the rhythmically consistent firing of neurons in response to a harmonious pair of frequencies. Now the researchers who developed the model report 2 September in Physical Review Letters that they have quantified the effect by calculating the information content of their model’s neural signals and showed that it increases for tone pairs that are more pleasant sounding. The model may also provide insights into other sensations besides hearing.
From here; do read the whole piece. It is short, lucid and also contains some nice pointers to other reading material towards the end, if you are so inclined.