How our brains process music

Recent technological advances in the field of brain anatomy and cognitive science such as magnetic resonance imaging (MRI) have allowed neuroscientists to make significant advances in explaining how the human brain converts sound waves into music. These findings are adding to an impressive body of evidence that suggests music can trigger physiological changes far beyond the purely cognitive. 

Music can be defined as organised sound comprising the following structural elements: pitch, timbre, key, harmony, loudness (or amplitude), rhythm, meter, and tempo. Processing these elements involves almost every region of the brain and nearly every neural subsystem. We are going to examine how this happens.

Sound does not exist outside of the brain; it is simply air molecules moving. Sound is produced by vibrating air molecules connecting with the eardrum at varying frequencies (pitch) and velocities (amplitude). The process starts with the brain’s primary auditory cortex receiving a signal from the eardrum/inner ear which immediately activates our ‘primitive’ brain, the cerebellum. The cerebellum is the oldest part of the brain in evolutionarily terms and plays an important part in motor control. It contributes to coordination, precision, and accurate timing of movements. The ear and the primitive brain are known collectively as the low-level processing units. They perform the main feature extraction which allows the brain to start analysing the sounds, breaking down the sensory stimulus into pitch, timbre, spatial location, amplitude, reverberant environment, tone durations, and onset times of different notes. 

This data is conducted through neurons in the brain; cells specialized in transmitting information, and the basic building blocks of the nervous system. The output of these neurons connects to the high-level processing units located in the frontal lobe of the brain. It is important to note that this process is not linear. The different regions of the brain constantly update each other with new information. 

Once the cerebellum has broken down the initial sensory stimulus it passes the signal to the thalamus which interrogates the signals for any signs of danger. It does this by communicating with the hippocampus, the brain’s memory center, for stored historical sound/danger associations. The thalamus links to the amygdala to initiate an emotional response (e.g. fear if a danger signal is detected) in much the same way as the amygdala works out how one feels about the sight of someone brandishing a knife. It’s at this point that the “fight or flight” response kicks in. It is through this same interaction between the low-level and high-level processing units that the brain categorizes sound into music. 

The brain is not like a warehouse or library of information. Historical information is stored in configurations of neurons. When a stimulus activates a certain configuration of neurons, historical information is retrieved. The high-level processing units construct musical features into a perceptual whole by constantly referencing historical information and additional stimulus passed on by the low-level processing units. As Daniel Levitin puts it in ‘This Is Your Brain on Music’, ‘music can be thought of as a type of perceptual illusion in which our brain imposes structure and order on a sequence of sounds. Just how this structure leads us to emotional reactions is part of the mystery of music’. 

So to understand how our brains process music we need to examine these neural codes. The activation of neurons is called ‘firing’. Firing is an electrical signal that releases chemical substances called neurotransmitters. These neurotransmitters swim in gaps between the neurons called synapses. Neurotransmitters not only cause a neuron to fire but can also prevent it from doing so. Some neurotransmitters are used throughout the entire nervous system; some are particular to certain brain regions, or even certain groups of neurons. For example, Dopamine produced by the nucleus accumbens, is critical to the co-ordination of movement, the regulation of mood and the brain’s reward system. This neurotransmitter is released when a drug addict receives a drug of choice, when a compulsive gambler wins a bet or when a chocoholic ingests cocoa. It is widely accepted that increased levels of dopamine result in a more positive mood which is why many of the newer anti-depressant drugs emulate this approach. Similarly, Serotonin produced in the brain stem is known to regulate mood and sleep. Again, many of the contemporary anti-depressant drugs including Prozac and Zoloft act as a Serotonin reuptake inhibitor, causing the neurotransmitter to act on the brain for longer periods of time.

It is because music unconsciously triggers these neurotransmitters that it has such a powerful influence over mood states. 

Aniruddh Patel of The Neurosciences Institute in San Diego regards music as a transformative technology because “not only is it a product of the brain’s mental capacities, it also has the power to change our brain.’ Phillip Ball, in his bestselling book ‘The Music Instinct’, goes even further to say that ‘regardless of whether evolution has given our brains musical modules, it seems to have given us intrinsic proclivities for extracting music from the world. Music is a part of what we are and how we perceive the world.’ 

Changes in mood are inextricably linked to changes in behavioural response and this is why music can be such a powerful tool to employ in a commercial environment. Structural elements of music have been proven to influence consumer behaviour. For example, increased volume of background music has been shown to increase the speed at which bar customers consume drinks, consequently increasing bar revenue over time. 

In ‘Fast music causes fast drinking’ Perceptual and Motor Skills, 75,362 (1992), H. McElrea and L. Standing found that fast music (increased tempo) leads to people drinking a can of soda 39% faster than slower music. Similarly, C Caldwell and S Hibbert (in The Influence of Music Tempo and Musical Preference on Restaurant Patrons' Behaviour’ 2002) found that when slow music was played in restaurants the time spent dining was 20% longer but 51% more money was spent on drink per head and 12% more on food per head. 

The benefits of music are not just limited to customers but can be applied to the workforce as well. 85% of MusicWorks research participants said listening to music they like whilst at work makes them much happier and the MusicWorks study also revealed that one-third of employees are less likely to take time off work if background music is played in the workplace. According to the Institute of Leadership & Management's website, managers could cut the number of sick days by seven million simply by switching on the radio.

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