How we use our brains to hear

2021-01-29 You hear with your brain, not with your ears.

Of course, we need our ears to capture sounds, but we only understand these sounds once they arrive in our brains. So hearing – and especially speech understanding – is a cognitive process, not a mechanical one.

In other words: hearing is thinking.
Our ears deliver all sounds to our brains. They do not choose what to send; in fact, they never rest. Even when we are asleep, our ears are sending sound information to our brains.

Our brain then does all the hard work. The brain filters out irrelevant sounds, like other people talking in a restaurant, and like traffic in the background. Without us realising it, our brains are constantly at work selecting what we hear, and deciding how much attention to give each sound.

But before any decisions can be made, our brains must first extract meaning from the mass of overlapping sound waves that fill the air. By taking the sound signals from both of our ears and comparing them, our brains locate the source of different sounds.

We use location information to determine which parts of this mass of sound are coming from certain objects or people. Or animals – these skills evolved during our primitive past, when effectively locating threats and food were critical to our survival.

 

The brain transforms sound into meaning
Once our brains have singled out a sound source, it compares these sounds to our memory. By doing this, it can determine if the sound is something we have heard before, and therefore something we know already. Equally, our brains sometimes find no reference in their memory bank. Then, it can add a new one, ready for comparison next time. In the meantime, we are alerted to danger by a sound of the unknown.

Once your brain has taken raw sound data from your ears and transformed it into meaning, it can extract more information about your surroundings. From the length of time it takes a sound to echo, and the amount of echo it creates, our brains give us a feeling for how big a space is. We also infer the type of surfaces there are in a room from the way they change the sound, as it bounces off them on its way to our ears.

All of these calculations happen simultaneously, in the brain. Since it is the brain that transforms sounds into meaning, good hearing isn’t simply a question of making sounds loud enough. Good hearing requires that we ensure the brain gets all the sound information it needs. It must not miss out on some frequencies, or some sounds from particular directions.

If your brain is not getting the right sounds to work with, it takes intense effort to extract meaning from the partial sound. Whenever there are missing sounds, the brain tries to fill the gap – an often difficult and exhausting process.

Hearing aids can support the brain
Instead of turning up the volume and overloading your brain, we need to support your brain by giving it the conditions it needs. To properly extract meaning, the brain needs access to the full soundscape, so it can naturally focus on the most relevant sound sources.

Modern hearing aids can provide this. With more powerful processors than ever before, they no longer need to narrow down the soundfield when you are in noisy environments. And when a skilled hearing care expert fits hearing aids, they can compensate for the missing parts of the soundfield, to restore the conditions in which your brain is designed to work.