Is the shape of our ear unique

Ears

Besides seeing, hearing is one of the most important human senses. The sense organs are a prerequisite for human spiritual development. There are two aspects to communication: understanding and being understood.

When hearing and understanding are impaired, every single encounter is affected. As a result, there is a risk of social withdrawal, which can also have psychological consequences.

But hearing is not just about communication. It is used to locate the sound source and thus it also helps us to recognize dangers in good time and to protect ourselves from them, e.g. from an approaching car.

The ear permanently supplies the brain with stimuli. This also creates alertness, vitality and creativity. Conversely, this explains why people with a hearing impairment often tire more quickly.

It is therefore important to consult a doctor as early as possible in the event of hearing loss - even if it initially appears to be minor - in order to clarify the cause and find a suitable therapy.

The ear is not only an important but also an extremely complex organ. The complex interplay of its individual parts brings sound to the brain, where a sound wave becomes the characteristic sound of a voice known to us.

The sound processing

The ear is divided into different areas: It consists of the outer ear, middle ear and inner ear. The hearing is connected to the auditory center of the brain via the auditory nerve. In sound processing, the sound passes through these individual areas before it arrives in the auditory center of the brain and is processed there.

The outer ear bundles the sound that occurs in the environment. The special shape of the auricle enables people to determine the direction from which the sound is coming. The outer ear is separated from the middle ear by the eardrum. The sound that hits the eardrum is transmitted to the inner ear via the ossicles of the middle ear. The so-called hair cells are located in the fluid-filled inner ear, which is also known as the cochlea due to its shape.

These are sensory cells that react sensitively to sound. The sensory stimuli picked up by the hair cells are then passed on to the auditory center of the brain via the auditory nerve.

Structure of the ear

The ear consists of three parts that work together to transmit sound waves to the brain and thus to the hearing process.

The outer ear

The outer ear includes the auricle and the ear canal. Since the ear canal is separated from the middle ear, which is located further inside, this part of the ear is also called the outer ear canal.

The main function of the outer ear is to bundle and transmit the sound coming from the environment. It also plays a role in directional hearing. The convoluted shape of the auricle aids the human ear's ability to localize sound waves.

The middle ear

The middle ear begins at the eardrum and consists of the three auditory ossicles, hammer, anvil and stapes. The eardrum is the border between the outer ear and the middle ear. It is a thin membrane.

When the sound hits the eardrum, it starts to vibrate. The vibration is then passed on to the three ossicles. The sound converted into mechanical energy reaches the so-called oval window, the border between the middle and inner ear. The oval window is closed by the footplate of the stapes. By moving the stapes, the sound energy is passed on to the fluid-filled inner ear.

The middle ear forms the so-called tympanic cavity. This is an air-filled area that also includes the ossicles. It is connected to the nasopharynx via the Eustachian tube (also known as the "ear trumpet"). This connection ensures that the pressure between the middle ear and the outside world is equalized.

++ More on the topic: Middle ear hearing loss ++

The inner ear

The entire inner ear is filled with fluid. Because of its shape, the inner ear is also known as the cochlea or cochlea. The sensory cells, so-called hair cells, which are responsible for processing the sound, are located in the passages of the inner ear. They are located in the inner ear canals and react with nerve impulses to the wave movements of the inner ear fluid.

There are different areas of the screw for the different sound frequencies. The hair cells for high frequencies are located at the entrance to the inner ear. Therefore, the sound waves act more intensely on these hair cells. The wave impulses picked up by the hair cells are converted into nerve excitations and passed on from the auditory nerve to the brain.

The cochlea is also connected to the organ of equilibrium. This is why dizziness can occur with some hearing disorders.

Auditory nerve and auditory center

The auditory nerve and the equilibrium nerve lie in a bony canal, the so-called internal auditory canal. The nerve fibers connect the inner ear to the hearing center of the brain.

Ascending orbits

There are inner and outer hair cells in the inner ear, each of which has different functions. While the auditory information is transmitted through the inner hair cells to the nerve pathway leading into the brain (the so-called ascending pathway), the outer hair cells primarily have the task of refining what is heard, i.e. to amplify sounds that are too soft and to weaken sounds that are too loud.

Descending orbits

The outer hair cells are mainly connected to the nerve fibers (descending nerve fibers) of the auditory nerve coming from the brain. After the sound is transmitted to the brain, our thinking center reacts and sends information back to the outer hair cells, which react accordingly and dampen or amplify the sound.

Cerebral cortex

In the brain, the further course of the acoustic information that comes from the inner ear is very complex. On the way to the cerebral cortex - the place where we consciously hear - the hearing information passes through various switching points such as the brain stem, the thalamus and the limbic system. These points all contribute to the overall auditory impression and set various reactions in motion. There are areas of the brain that specialize in processing the emotional meanings of sound and other areas that are responsible for processing language.

Our listening area

The hearing area is the area of ​​sound that can be perceived by the human ear. In order for us to be able to hear noises, they have to be loud enough on the one hand and be in a frequency range that is audible on the other.

The frequency range that can be heard by humans is roughly between 20 and 20,000 Hertz. The human hearing range is limited below by the hearing threshold and above by the pain threshold. If the volume of the acoustic stimuli in the audible frequency range is too low, they cannot be perceived. This is also the case if the volume is too high. In this case, acoustic stimuli are only perceived as an unpleasant, painful experience.

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Authors:
Dr. med. Stefanie Sperlich
Medical review:
Univ.Prof. Dr. Sasan Hamzavi
Editorial editing:
Philip Pfleger

Status of medical information:
swell

Gürkov R .: Basics ear, nose and throat medicine. Elsevier, Urban & Fischer Verlag; 3rd edition 2013

Kippenhahn K .: I think I can't hear properly: hearing loss, tinnitus & Co. Schattauer Verlag 2011