Have you ever wondered how we perceive sound? What happens in our ears and brains that allow us to hear things?

 

We exist in our worlds through the sensory inputs we receive from our environments. This information can reach us through our eyes, nose, hands, mouths, and of course, ears. Many of us without any hearing impairements are hearing thousands of sounds on a daily basis and we rarely wonder how it is that we are capable of doing this. Sounds give us critical information about our surroundings. For example, if someone calls out our name, we immediately turn towards the sound to know what is going on, or we have the capability to process that sound and immediately know who is calling us. We can sense danger if we are out in the wild and need to know if a predator is getting close to us. Mothers, of course, develop extreme sensitivity to an infant's cry and are ready to protect the child immediately. Of course, hearing allows us to not just enjot beautiful music, but also to learn it, asses our learning curve, and play it as beautifully and sensitively as we can.

Here's a brief explanation of how our ears work.

When sound waves from a sound source travel to our ears, they hit the Outer Ear. This is pretty much the part of the ear that we can visibly see. Once the sound travels inside and into the Middle Ear, it hits the ear drum-a thin membrane attached to the small bones right behind it- that most people are aware of as well. Once the vibrations travel through the ear drum, they vibrate the three small middle ear bones known as the Hammer, Anvil, and Stirrup. The vibrations of these bones then travel into the Inner Ear, which houses one of the most important parts of the hearing process, the Cochlea. The cochlea is a tiny coiled system that resembles a snail shell. If we imagine this shell as an uncoiled, straight system, we can understand it a bit more easily. The uncoiled cochlea has a membrane that exists from one end to the other, known as the Basilar Membrane. Similar to an instrument's strings, this membrane varies in width and stiffness, thereofre, it is sensitive to different frequencies at different areas. The membrane is widest and least stiff at the apex of the cochlea and narrowest and most stiff at the base. This means that higher frequency sounds localize near the base of the cochlea (where the inner ear bones meet the cochlea) while lower sounds localize near the apex (further coiled in tip of the cochea). Once the part on the cochlea corresponding to the right frequency coming from the sound stimulus is activated, the Hair Cells, which are sitting right next to the basilar membrane, are activated. These hair cells are what translate vibrations into electrical signals that travel through the auditory nerve, into the brain, and we counsciously become aware that we are hearing a sound.

 

Are you interested in getting a more in depth analysis of how we hear? Let me know and comment below! There is plenty more to dig deep into when it comes to how we hear.


Posted On : Friday 16 December 2016
Author : Mojtaba Asadollahzade

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