The key to pleasant music may be that it pleases our neurons, a new mathematical model developed by Russian scientists has suggested.
The new model suggests that harmonious musical intervals trigger a rhythmically consistent firing pattern in certain auditory neurons, and that sweet sounds carry more information than harsh ones, New Scientist reported.
Since the time of the ancient Greeks, we have known that two tones whose frequencies were related by a simple ratio like 2:1 (an octave) or 3:2 (a perfect fifth) produce the most pleasing, or consonant, musical intervals.
But it was unclear whether consonant chords are easier on the ears because of the way the sound waves combine in the air, or the way our brains convert them to electrical impulses.
"We have found that the reason for this difference is somewhere at the level of neurons," said Yuriy Ushakov at the N. I. Lobachevsky State University of Nizhniy Novgorod in Russia.
Ushakov and colleagues considered a simple mathematical model of the way sound travels from the ear to the brain.
In their model, two sensory neurons react to different tones. Each sends an electrical signal to a third neuron, called an interneuron, which sends a final signal to the brain.
The model's interneuron fires when it receives input from either or both sensory neurons.
However, the signals from the sensory neurons arrive at the same time if the tone is consonant, and so the interneuron still fires just once, then waits until it "recharges" before it fires again. The result is a regular train of pulses.
By contrast, the signals from dissonant tones arrive at different times and so generate an irregularly spaced train of pulses in the interneuron.