Your heart beats faster, the palms sweat and the part of your brain named Heschl’s gyrus lights up like a Christmas tree. Probably you have never thought in detail about what happens to your brain and body when you listen music, but is a question that has intrigued the scientists during decades: ¿how something so abstract as music provokes such a consistent reaction? In a new study, a researching team from the USC, supported on artificial intelligence, investigated about how music can affect the brain, body and emotions of the listeners.

The researching team analyzed the cardiac frequency, the galvanic answer of the skin (or the sweat glands activity), the brain activity and the subjective feelings of happiness and sadness in a voluntary group while they listened three unknown different pieces of music. From the 74 musical characteristics examined, the researchers found that the dynamic, the register, the rhythm and the harmony were particularly useful to predict the answer on the listeners.

«Having a holistic of the musical perception, using all the different types of musical predictors, gives us a vision without precedent of how our bodies and brains answer to the music », said the main author of the study, Tim Greer, student of a compute sciences doctorate, and member of the Signal Analysis and Interpretation Laboratory from the USC (SAIL).

The Contrast is Crucial

Among their findings, the researchers noticed that music powerfully influenced some brain parts in the auditory complex named Heschl’s gyrus and the superior temporal gyrus. Specifically, the brain responded to the pulse’s clarity, or the heartbeat strength (in a few words, its gyrus will be alive when hears Bad Romance by Lady Gaga).

They also discovered that changing dynamics, rhythm and timbre, or the introduction of new instruments, provokes an upturn in the reaction. In other words, the contrast is crucial. For example, the gyri get activated when there is a change of dynamic or «volume».

«A composer’s work is to take you to a roller coaster of emotions in less than three minutes, and the dynamic variability is one of the ways for this to accomplish».

The team also discovered that the galvanic answer of the skin, basically, a sweat measure, raised after the introduction of a new instrument or the beginning of a musical crescendo: «When every new instrument gets in, it can be seen a peak on the collective response of the skin», Greer said.

Besides, the most stimulant music moments where preceded by a raise of the complexity level in the song. In essence, how more instruments were in the song, more people reacted. (Think: in the first section of Tubular Bells by Mike Oldfield, while the song develops a crescent rhythm, it adds more instruments).

Listening to Chopin’s Nocturne in E flat major (Op. 9, No. 2). Video: USC Brain and Creativity Institute. 

New Territory

For this experiment, the team selected three emotional music pieces that didn’t contained lyrics and weren’t very familiar, so that it didn’t added any memory element to the listeners response. (Hear a song that sounds in the background during a tooth extraction, for example, could skew its perception).

At the experiment, 40 volunteers listened a series of musical extracts, sad or happy, while their brains where scanned through magnetic resonance. This was made at the Brain and Creativity Institute from USC by Assal Habibi.

To measure the physic reaction, 60 people listened music on earphones, meanwhile the cardiac activity and the skin conductance were monitored. The same group also qualified the emotions’ intensity (happy or sad) from 1 to 10 while they were listening the music.

Then, the informatic staff analyzed the data using artificial intelligence algorithms to determine which auditory characteristics answered consistently on the people.

In the past, the neuroscientists who tried to understand better the music impact on the body, the brain and emotions, have analyzed the brain scanners by magnetic resonance in short segments of time, for example, observing the brain reacting to two seconds of music.

In the opposite, this study, used algorithms to analyze the collected data in the lab, the scientists could observe how people felt listening to the music during longer periods, not only trough brain scanners, but combining data in other ways.

«The new multimodal informatics approaches help to not only illuminate the affective human experiences trough music in a brain and body level, but also to connect them with the way individuals really feel and articulate their experiences», said the professor Shrikanth (Shri) Narayanan, co-author of the study.

Feeling Good

Besides helping the researchers to identify songs for the perfect exercise, the study or the playlist to sleep, the investigation has therapeutic apps; it has been proved that music calms anxiety, reliefs the pain and helps people with disability and dementia.

«From the therapy’s perspective, music is a really great tool to introduce emotion and generate a better mood», said Habibi.

Using this investigation, we can design musical stimulus to depression and other mood disorders therapy. It also helps us to understand how emotions are processed in the brain.

According the researchers, the future studies could analyze how different kinds of music can positively manipulate our emotional answers, and if the intention of the composer matches with the perception of the listener of a musical piece.