Auditory transduction and pathways

In auditory transduction, auditory refers to hearing, and transduction is the process by which the ear converts sound waves into electric impulses and sends them to the brain so we can interpret them as sound. And the ear itself is made up of three parts: the outer ear, the middle ear and the inner ear, and all three play a role in hearing.

You can think of the ear like a house, with a porch, a living room and a short corridor that leads to two bedrooms at the end. The porch would be the outer ear, made up of the pinna and the external auditory canal. The middle and inner ear, would be the actual “house”, carved inside the temporal bone. The middle ear is like a living room, furnished with the tiny ear bones - called the malleus, incus, and stapes - that articulate or touch one another. The inner ear is the rest of the house, made up of a corridor and two rooms -  where the corridor is the vestibule, and the two rooms are: the cochlea, which is anterior to the vestibule - so towards the front of our head -  and the semicircular canals - posterior to the vestibule, so towards the back.

Now, the outer, middle and inner ear are functionally connected to one another, which is crucial for hearing. Between the outer and middle ear there is the tympanic membrane - or eardrum - and between the middle and inner ear there are two windows: the oval window, above, and the round window, below. So, when you hear the wind rustling through the leaves, the resulting sound waves are directed by the pinna into the external auditory canal, and they reach the eardrum, making it vibrate. The malleus is attached to the eardrum, so the vibrations are transmitted along the tiny bones - from the malleus to the incus, and then from the incus to the stapes. The foot of the stapes rests on the oval window - and since the oval window is about 20 times smaller than the eardrum, the sound waves are amplified as they vibrate their way across the tiny bones. From the oval window, the vibrations are transmitted to the inner ear. The part of the inner ear that transforms sound waves into electrical impulses is the cochlea.