Device a person’s ear: structure of the hearing aid
How to construct a hearing aid of the person?
According to biologists, the auditory apparatus of man is the most perfect of all bodies responsible for sensitive perception of the world. This is due to the fact that it identified the largest concentration of nerve fibers.
The organ of hearing is the ability to capture a temporary difference between the arrival of sound to one ear and another. As a result the person can determine the direction from which the moving sound wave. This ability of hearing is called the binaural effect.
The structure of the ear
A hearing aid is divided into the following parts:
- outer responsible for the capture of sound;
- medium containing multiple elements, amplifying sound waves;
- internal, which converts the incoming ambient waves into electrical impulses.
In other words, the system of the organ of hearing consists of three elements:
- the receiver;
It’s a fairly complex structure of human hearing system provides a sensitive perception of the surrounding space by transforming external sounds into electrical impulses perceived by the brain.
The outer part
Blood to the external ear on the branches of the carotid artery. Innervation occurs through the trigeminal and vagus nerves. The last adjacent to the rear wall of the auditory canal, in this connection, when the mechanical irritation of this part there is a reflex cough.
The lymph fluid that descends from the auditory canal by nodes that are placed directly in front of the sink. This explains the reason why any inflammatory process occurring in the ear, will inevitably lead to swelling and soreness of these nodes.
The outer part of the human ear is divided into the following elements:
- the ear canal;
The auricle is a thin layer of cartilage (thickness less than 1 mm), covered with leather. Below that is the region consisting of fat tissue. The shell has a concave structure, and along its edge from the roller (curl).
In the inner part is protivotumanok. It is separated from the roller by the so-called rook, which is a recess elongated shape. This formation is located between the ear canal and protivotumanok. The second recess is known as the shell cavity. Directly in front of the ear canal is the tragus.
The Pinna performs the following functions:
- the reception of sound;
- transmission of waves into the inner ear.
Help. Cartilaginous education (tragus and protivotumanok) have a high sensitivity.
The ear canal
The length of the auditory canal does not exceed 2.5 cm, and its diameter can reach 0.9 inch. At the beginning of this part of the ear is another cartilaginous education shaped groove. Here are santoramaa cracks that directly come into contact with the salivary gland.
The cartilage then goes into the bone tissue. The ear canal has a curved structure. It is formed of leather, which is combined with sulfur and sebaceous glands. Last perform the following functions:
- secrete a secret;
- protect the ear against mechanical damage, chemical substances, infectious agents and exposure to high temperature.
Sulfur generated from sulfur glands removed spontaneously during chewing of food. The end of the auditory canal is necessary to the eardrum. This part of the outer ear also connects to the lower jaw and the facial nerve.
The eardrum is a fibrous plate having an oval shape and translucent structure. In length it stretched to 10 mm, its width does not exceed 9 mm, and the thickness averages 0.1 mm.
In relation to the auditory passage of the ear drum is at a certain angle.
The greatest stress falls on the middle part of the membrane. The eardrum acts as a barrier, separating the outer portion of the ear of the average.
The middle part
The middle part of the human ear comprises the following elements:
- the tympanic cavity;
- the auditory ossicles;
- Eustachian (auditory) tube.
The tympanic cavity
This part of the middle ear is approximately 1 cubic cm and located near the temporal lobe of the head. Here are the auditory ossicles associated with the eardrum. Just above this cavity meet the pneumatic cell. They help surgeons to perform the operation, acting as a kind of landmark.
The auditory ossicles
Their main function is to transfer sound waves further to the inner ear Department. Bones consist of three elements:
- the hammer is connected by a lever with an ear ear and directing sound waves to the anvil;
- the anvil, which passes the vibrations on to the stapes;
- the stapes, connecting the anvil with the inner ear Department.
Help. The smallest bones of the human body are the auditory ossicles.
Length of auditory tube does not exceed 3.5 cm, and its average diameter is 2 mm. the Upper part of this element comes to the tympanic membrane. The lower part of the Eustachian tube for the nasopharynx.
This part of the middle ear is divided into two sections, which are interconnected by a so-called isthmus.
On top of Eustachian tube formed bone tissue. After the isthmus it consists of cartilage.
Lower part of the tube is constantly closed up.
It opens only when the actions of the oral cavity: chewing, swallowing, etc. the Mucous membrane of the Eustachian tube is formed of epithelium on the surface of which has small cilia. The latter, in turn, engaged in drainage of the Eustachian tube.
The main function of this component is the middle part of the ear is equalization of pressure inside your hearing.
The inner part
Device inner ear of a human has the most complex structure. It is more like a labyrinth, divided into the following divisions:
- channels, repeating the shape of the cochlea.
Often the inner ear called the membranous labyrinth, enclosed in the temporal part of the head.
Different snail spiral shape and surrounds the bone shaft. Its length does not exceed 32 mm, and the width of the lower part is only 9 mm. the snail Itself through plates of the same spiral shape extending inside of the entire maze is divided into two small channels.
In the lower part of this element of the inner ear are nerve cells. It is in the cochlea converts sound waves into electrical impulses, which then enter the brain. The upper part of the snail is a so-called organ of Corti, or the auditory analyzer.
The cavity of the inner ear is filled with fluid:
- the perilymph which in composition resembles the plasma of human blood;
- endolymph has a similarity with the cell liquid.
The disruption of communication between the endolymph and the perilymph is the reason for the increase in pressure inside the ear.
The threshold is a cavity which delimits a spherical pouch located near the snail stairs and the lower channels. This part of the inner ear consists of two Windows:
- oval, which is closed by the stapes;
- round, which performs the same role as the eardrum.
The vestibular apparatus
Three channels, located in the inner ear, include special receptors. The latter are the human vestibular apparatus. Buds are cylindrical and resemble the bulb.
They are divided into:
- stereocilia that the displacement caused by motion of the sound waves are coming in excited state;
- kinocilium, which are responsible for deceleration of the sound wave.
Through these elements people perceive their location in space. Vestibular system also provides coordination and keeps the body in equilibrium position.
The structure of the ear of the newborn
The ear of a newborn has a number of distinctive features, which are about four years away:
- Shell has a soft structure, and the lobe to the curve of becoming final form for several years.
- The ear canal is almost entirely composed of cartilage. The walls are flush with each other.
- The eardrum is located in a horizontal plane relative to the auditory canal and has the same dimensions as an adult. However, she has a more thick texture.
- The tympanic cavity some time remains open. The result is an ear infection can penetrate into the brain, causing the development of meningitis.
- Eustachian tube disposed at a smaller angle and has a larger diameter than that of an adult.
The mechanism of sound perception
The signal transmission is as follows:
- Passing through the outer ear, the sound wave causes vibrations of the ear drums.
- The auditory ossicles act as an amplifier of oscillations and contribute to the sound transmission next to the membrane.
- Emerging pulsating movement stabiliziruemost in the inner ear Department.
- The fluid that circulates through the ducts of the cochlea, sending waves on to the membrane.
- In the end, a sound wave, reaching the basilar membrane, is converted by receptor cells into electrical impulses and sent to brain.
The device allows the human ear to perceive sound signals in a wide range. The external part of the hearing aid, each person has its own individual characteristics. However, middle and inner ear of all people are constructed in a similar manner (excluding congenital abnormalities).
You should regularly monitor the hygiene of the organs of hearing and in a timely manner to treat infectious diseases. According to studies, people suffer heavier loss of ability to hear than blindness.