Life without It is only Silence

We use your eyes to perceive the things that speak with the wavelengths of light. We use ears to perceive other wavelengths called "sound," caused by vibration of molecules.

Wavelength of sounds that ear can perceive ranges between 20 and 20,000 Hertz. It can sense frequencies of sound that are above or below those limits. Indeed, it would be better to call this advantage rather than "inability." If it had not been created with this limited capacity, we would have been facing unbearable pain in our head. If an ear had been made to work with a wider range of hearing, we would have been disturbed with the footsteps of a little ant, the moaning of an insect laying eggs, the buzzing of beehives, and the sound of the fluttering birds. Therefore, the fact that it has sufficient sensitivity for us to meet our needs is an advantage.

Do not ever think that ear’s outer, visible pan is too simple. Its outer ear, which sometimes turns red when we are nervous, is placed in the best position according to the shape of our head so that it can receive sounds in a most efficient way. Because it is made up of elastic cartilage, its outer ear (A) is very flexible, and it won't break when we lie on it. The curves on it (known as the helix) and the hairs inside its channel are not made without a reason, either. Its cartilages have the perfect shape to channel sounds down towards its middle ear according to sound intensity and the direction it comes from. Because this special shape is formed according to the genetic code of a person, it is different in every person. The hairs in the canal serve to protect it from foreign objects like insects or dust. The canal that connects its outer part to a middle part is pretty wide, but if too much fatty wax accumulates here, it might experience temporary hearing loss.

The outer part is followed by the middle ear, which begins with the ear drum (tympanic membrane). Attached to this thin ear drum are three bones: the malleus, the incus, and the stapes, which are all placed in order. These little bones are jointed to each other at an angle of 105 degrees. With an action like a piston, they amplify even the smallest sound vibration coming from the ear drum and transmit it to the middle ear. Middle ear space is connected to our pharynx by a very thin canal called the Eustachian tube. In order to protect the ear drum from rupture, it is recommended that you open your mouth during an explosion or an intense sound. In that way, the sound waves that enter through our mouth will balance with the sound waves in ear’s canals so that the ear drum is protected.

The inner part, followed by ear’s middle part, is the most viral and sensitive area. Therefore, it is surrounded and protected by the bones of our skull. This inner part, which is an amazing piece of art and technology, comprises two wonderful receptor components. Those two little parts are placed in the same narrow area inside the temporal bone, but they perform different tasks. One of them is the cochlea, which is involved in hearing. The other part is the balance (vestibular) canals, consisting of semicircular canals, saccule and utricle. This balance organ enables you to stand straight and walk, run, or move without bumping or falling.

Like carved marble or forged metal, those parts are crafted out of bones that form a beautiful and intricate whole. Its cochlea is divided widthwise by a bony tube. The upper compartment above the tube is connected to an oval window, which is an outlet to the middle ear. The lower compartment below the tube is connected to a round window. Its inner part is a labyrinth of fluid-filled tubes. The fluid in the bony labyrinth, between the bone and membranes, is called perilymph, and the other fluid within the membranous structure is called endolymph.

Situated on the basilar membrane of its cochlea is a very small and special organ that is called the Corti’s organ. The organ of Corti contains the hearing cells (or hair cells), the receptors that are sensitive to sound waves, and other supporting cells. Because the length of the cells in the organ of Corti varies, different parts of ear’s cochlea are sensitive to sounds of different wavelengths.

The sound waves travel via the malleus, incus and the stapes and through its oval window, agitating the perilymph of cochlea. After that, the sound waves cause Reissner's membrane in cochlea to vibrate, which then results in wave movement in endolymph. The wave movement continues along this membrane until it reaches Corti’s organ. Special receptor cells (or hair cells) of Corti’s organ are the ultimate vibration receptors. Their surfaces consist of very small strands (cilia). Those little strands bend and twist when sound waves are received. Right at this point, a very important event occurs: it is movement of these strands which converts mechanical energy (that is produced by vibrations of sound waves) into electrical impulses. Those electrical impulses are then sent to our brain via the auditory nerve (nervus cochlearis) of the brain, where they are perceived as "sound." The same sound waves continue their way to the perilymph and pass into the round window, section between the middle ear and inner ear. The round window pushes out to dissipate sound vibrations in the perilymph and thus lessens their pressure.

Speed of hearing depends on speed of the sound that travels through membrane and little bones. However, once sound waves begin to pass to our brain as an electrical impulse along the auditory nerve, the hearing process increases its speed. Then our brain immediately interprets and reacts to the sound waves. We are not aware of all these rapid activities which are done perfectly in fractions of a second. We only say that we can hear something ordinarily.