According To Your Brain, Songs Are Different From Instrumental Music Or Speech - Forbes

When you listen to music, your brain processes this in a different way than when you’re listening to someone speak. So where does that leave songs? In a new study, researchers found that there is a small area of the brain that’s triggered by vocal music, but not by either speech or instrumental music.

2018 Fresh Grass Festival — When you hear singing, your brain processes that in a different way than it does instrumental music or spoken word. Here: Sara Watkins, Sarah Jarosz, and Aoife O'Donovan of I'm With Her singing around one microphone during the FreshGrass Music
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This study was uploaded as a preprint to BioRxiv, which means that it has not yet been peer-reviewed by other researchers, but the same group of researchers has previously published other studies that look at how the brain responds to a series of different sounds. In 2015 they found that music and speech were processed in different parts of the auditory cortex.

What’s particularly interesting about this new study is not just the fact that it shows that our brains consider songs a whole separate thing from either music or speech, but also the way the researchers carried out the experiments. Instead of using functional magnetic resonance imaging (fMRI) like they did in previous studies, here they measured brain activity directly on the surface of the brain.

fMRI locates activity based on blood flow through the brain, and roughly finds the active area, but it can’t pinpoint the area in much detail. A more “high resolution” method to look at brain activity is by using electrocorticography, or ECoG. In the current study, neuroscientist Sam Norman-Haignere and his colleagues wanted to repeat some of their earlier fMRI experiments with ECoG, to see if they could find more accurate locations of music and speech in the brain.

ECoG is a surgical procedure. The electrodes need to touch the brain itself so the skull needs to be opened. It’s very invasive, so - unlike fMRI studies - it’s not something you can ask people to volunteer for. But ECoG is routinely used on people who have a form of epilepsy that only affects a small area of their brain. These people qualify for a surgical procedure where the part of their brain that’s causing their seizures is removed. To prepare for that surgery, doctors first need to pinpoint the exact location of the affected area, and they use ECoG for that.

So to find volunteers to listen to a series of music, speech, and other sound samples, the researchers approached people who were about to undergo an ECoG procedure for epilepsy treatment, and who were willing to take part in this experiment. They found thirteen volunteers this way. Each one of them listened to a series of 165 sounds and researchers used the ECoG measurements to find which parts of the auditory cortex were activated.

The sounds were all short samples of familiar things. A dog barking, for example, or the ping of a microwave. The sounds were grouped into different categories, and this is where certain patterns started to show up. Samples in similar categories would activate certain areas of the brain, suggesting that that was where the sound was processed.

Some of the samples were of instrumental music, speech, or vocal music. There was some overlap in the brain regions that these samples activated, but there was one part of the auditory cortex that seemed to respond very specifically to vocal music (songs) rather than speech or instrumental music. In the earlier research using fMRI this hadn’t been noticed, probably because the resolution isn’t as clear as it is with ECoG.

From this experiment it looks like your brain processes songs in a different way than either speech or instrumental music. It’s not clear why, or what it means, but Norman-Haignere and his co-workers offer some suggestions in their paper. For example, it could be related to the fact that the earliest music was mainly vocal, or because we’ve learned over time to recognize the melodic vocal line in a song as information separate from the rest of the music.

Whatever the explanation, this discovery is another piece of the puzzle in understanding how music is processed in the brain.

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