posted December 15 2022 by Jord

The sound of your thoughts

Sound is everywhere. We constantly hear sounds, even when we think it's quiet. When you pause to think about it, our body's ability to translate all these sounds into a mental picture is incredible. Not only is our brain able to generate meaning, it can also locate the source of the sound and filter out irrelevant noises.

The ear...

...is essential in the process of hearing. And there's a lot more to our ears than we see. Sound waves enter the outer ear, also called the pinna. The funnel-like shape filters and amplifies sound waves from our environment before they're sent into the ear canal. This is where sound waves hit the eardrum, causing it to vibrate. The vibrations then go through the inner ear, where three tiny bones amplify the vibrations and send them to the shell-shaped cochlea. Hair cells convert these vibrations into electrical impulses. The auditory nerve then sends those signals to...

...the brain...

...which is where the real magic happens. Our brain is able to turn the electrical signal into a sound that we can actually recognize and understand. The auditory cortex plays a crucial role in this process. It starts with analysing low-level features, such as loudness and pitch, but it can also locate the source of the sound production, such as speech or a honking car. Besides, the brain distinguishes relevant sounds from background noise. And it even automatically turns up the volume when we speak.

Internal voice

In short, our ears and brain form a team that allow us to perceive the world around us. But how do we perceive ourselves? What do our thoughts sound like? Interestingly, this differs for everyone. Some people experience an internal voice. They think in words, expressed by their own voice, but in their head instead of aloud. Other people have no inner voice at all, and some hear dozens. Thinking about it - whatever that may sound like - breaks your head.

Musical hallucination

But it may expand even further than those voices. There is a thing called musical tinnitus or musical hallucination, which refers to the experience of hearing music when none is being played. This can be a result of epilepsy, Alzheimer's disease or brain tumours. But in many cases, there is no underlying cause found...