From the moment a sound is emitted to when we feel it is a long journey, with the synchronous coordination of many organs inside the ear and the brain.
Sound is created by vibrations so it travels through space in the form of sound waves. The outer ear with a special structure will provide maximum support for catching these sound waves and directing it into the ear canal, which is also the beginning of the journey of sound into the brain.
Through the ear canal, sound waves will reach the eardrum: The organ is as thin as a paper but very strong, about 9mm high and about 8mm wide, with a structure of 3 layers; When sound waves strike the eardrum, this organ vibrates, the vibrations are transmitted to the structure consisting of 3 small bones right behind the eardrum, namely the malleus, incus and stapes. Besides transmitting, these bones also help amplify vibrations from the eardrum, before the vibrations caused by these sound waves reach the cochlea.
The cochlea is an organ shaped like a snail shell, about the size of a pea. The inside of the cochlea contains fluid, and sound waves create ripples in this fluid. Underneath the fluid are filamentous auditory receptor cells, the waves of fluid in the cochlea will simultaneously cause the receptor cells to vibrate. The special thing is that in the cochlea, there are many types of auditory receptor cells, each of which is responsible for responding to different sound frequencies. Specifically, receptors located at the bottom of the cochlea recognize high-pitched sounds like a flute. Meanwhile, receptor cells at the top of the spiral take on a trumpet-like bass.
When the receptor cells vibrate, ions fall to the base of this fibrous cell and attach to neurotransmitters, triggering the generation of electrical signals that are transmitted to the brain through the auditory nerve. . Finally, the central nervous system will decode these signals and help us perceive the sound that has just been emitted.