Bone conduction hearing aids are in-the-ear. Auditory ossicles: general structure

Ecology of life: The problem of hearing correction with bone conduction devices for a long time rested on the need for surgical intervention. However, today we already have several developments that exclude the operation: one of them is ADHEAR.

The problem of hearing correction with bone conduction devices for a long time rested on the need for surgical intervention. However, today we already have several developments that exclude the operation: one of them is ADHEAR.

There may be fewer indications for wearing bone conduction devices, but at the same time, the restoration of hearing with the help of them used to take place in several stages: first, it was necessary to implant a titanium implant in the skull, then let it “take root” for about six months, and only then implant amplifier processor.

At the same time, for example, operations might not be shown to children, and this affected the quality of sound transmission. Of course, it was possible to use special headphones, but the scope of the headphones is limited, and this complicated communication with people.

We recently wrote that Oticon presented its own version of a bone conduction device for children. However, ADHEAR looks better, and here's why.

Both devices are non-surgical ways to improve hearing, but ADHEAR wins in the way it is attached. The Oticon is comfortably attached to the head with a special elastic headband, and this can (and will) be both a physical and an ethical inconvenience. It cannot but cause a certain pressure on the skull, and unnecessary questions cannot be avoided.

ADHEAR is attached with an adhesive surface that is light, invisible and does not put pressure on the skin and bones of the skull, which was chosen as one of the key advantages.

Next comes the processor, which has the function of intelligent adaptation to the environment, several microphones that provide noise reduction, screening out unnecessary noise and stable feedback!

Plus, what is important and unique at the moment: the developed ADHEAR device has Bluetooth synchronization, in other words, it will also act as a headset, so now you do not need an additional device for this purpose!

The only thing that can become some kind of fly in the ointment is a two-week autonomy, but given the compact size, the gadget will probably charge quickly. We thought about the children additionally: there are proposals for the individualization of the device.

Active bone conduction VS passive bone conduction

Without going into science, we can basically say that passive bone conduction is, of course, safer anyway. Passive bone conduction devices are understood as devices that do not require any, even the slightest surgical intervention.

Under active, respectively, the opposite is true: even a minimally invasive method of implantation can be fraught with irritation, rejection and the inability to wear the device in the future. To be fair, the statistics are low, but the likelihood is not very comfortable feelings in terms of emotional background and additional attention and care for the implantation site.

Both Oticon and ADHEAD devices are passive devices, similar to bone conduction headsets, but acting as full-fledged hearing aids, and, according to their creators, without any noticeable loss in signal transmission quality, as well as with additional amenities: ADHEAD does not squeeze the skin and bones, and also has a Bluetooth sensor. published

bony ear canal formed by parts of the temporal bone. Its anterior and inferior walls are formed by the tympanic bone, the superior and posterior by the scales and the mastoid part of the temporal bone. In the distal part of the passage there is a groove (sulcus tympanicus), into which the tympanic membrane is inserted, surrounded by a tendon ring (annulus tendinous).

In the upper section passage, formed by scales, this furrow is interrupted (incisura Rivini); at this point, the shrapnel part of the membrane is directly attached to the bone. The skin lining the external auditory meatus in its fibrocartilaginous section is loosely connected to the underlying tissues and is supplied with hairs, sebaceous glands, and sulfuric (apocrine) glands.

Oily and thicker, the sticky part of earwax is produced by the sebaceous glands of the hair follicles, while the secretion of the sulfur glands is more liquid. The sulfur glands have a tuboalveolar structure. The walls of the secreting part consist of cells of a single-layer cubic epithelium containing brown-yellow pigment granules.

excretory ducts surrounded by smooth muscle fibers. The dense secretion of the sebaceous glands is diluted with the secretion of the sulfuric glands, and the sulfur is excreted by the movement of the jaws.

Skin in the bone ear canal is thinned (up to 0.1 mm) and devoid of hairs and glands. The epidermis is very loosely connected with the corium, while the deep layer is very tightly connected with the periosteum; only the epidermis passes to the tympanic membrane. A narrow strip of skin stretches along the upper wall of the bony auditory meatus, which does not differ from the skin of the cartilaginous region and passes to the tympanic membrane along the handle of the malleus (stria malleolaris).

Practically the relationship of the walls of the external auditory canal to the surrounding formations is important. In front and below, the fibrocartilaginous section of the auditory canal and partly the bone section are in direct contact with the parotid gland, the sphenoid process of which is embedded between the anterior wall of the passage and the articular process of the lower jaw.

Anterior wall of ear canal also borders directly in the cartilaginous and bone parts with the articular head of the lower jaw. This explains the sharp pain in the ear that accompanies chewing movements with otitis externa (furuncle). Injury to the lower jaw due to a fall on the chin or a blow to the latter is sometimes accompanied by a fracture of the anteroinferior wall of the ear canal.

Posterior wall of the bony auditory canal formed by the anterior wall of the mastoid process; in the depth of the wall is the descending part of the facial nerve. When the posterior wall is removed in the case of a radical operation, its deep section is preserved in the form of a so-called spur. With good pneumatization of the mastoid process, the posterior bone wall of the auditory canal is very thin. The upper-posterior wall of the auditory meatus is the anterior wall of the antrum.
The swelling of this wall and its omission are, as you know, a valuable symptom of mastoiditis.

Upper wall of the bony auditory canal, formed by the scales of the temporal bone, consists of two cortical plates, between which there is a diploetic and partially pneumatic bone tissue. The shorter upper plate is part of the bottom of the middle cranial fossa, formed anterior to the fissura petrosquamosa by the upper surface of the temporal bone pyramid.

More long bottom plate, equipped with a rivinian notch, is the outer (lateral) wall of the attic. Surgical access to the epitympanic space is provided through this wall.
The lower wall of the bony auditory meatus, dense and wide, is also the outer wall of the lower part of the tympanic cavity.

It is no secret that the great German composer began to lose his hearing at the end of his days. But not everyone knows that the "Viennese classic" came up with a way to deal with deafness and continue to write music. Beethoven held a wooden stick between his teeth and played the piano. The wood resonated with the bones of the jaw, and the musician heard the melody.

It is now clear that the composer suffered from conductive hearing loss, when high tones are lost, and loud music causes pain. Today, an audiologist would offer a bone hearing aid, and Beethoven could create and enjoy the whole gamut of sounds. These devices are recommended for patients with impaired sound conduction at the level of the outer and middle ear.

How does such a device work?

A hearing aid is a special device that amplifies the sounds of the surrounding world. In 70% of cases, people have sensorineural hearing loss, in which intra-ear or behind-the-ear external devices are used.

The conductive view requires a different approach. In this case, the passage of sounds through the middle ear to the eardrum is difficult. Bone conduction devices help patients with this type of disease.

The device converts sound into vibrations that are transmitted to the skull bone, then to the cochlea of ​​the inner ear.

In addition to conductive hearing loss, bone devices are used in such cases:

• purulent bilateral otitis, which has passed into the chronic stage;
• inflammatory processes;
• the presence of cavities that have formed due to postoperative mastitis;
• bilateral artesia - the absence of auditory canals.

The evolution of hearing aids

The first generations of bone conduction devices were bulky steel headbands that caused serious discomfort to patients.

Later, special glasses appeared with a device built into the frame. But here the same drawback remains: the vibrator puts pressure on the head and causes discomfort and even a headache.

The situation changed when a new generation of bone apparatus appeared. Among these is the Austrian system MED-EL Bonebridge.

The device consists of two parts:

• the Amade audio processor perceives the surrounding signals and transmits to the bone implant;
• BCI 601 titanium implant, which is implanted under the skin behind the ear.

The device bypasses the "problem" areas of the ear and directs sounds directly into the cochlea. At the same time, a person hears natural sounds, without tinnitus and discomfort.

Bone hearing aids of a new generation are now available to Ukrainian patients. Bonebridge devices are installed at the Kind Interhearing Center. These devices make life brighter and more interesting!

The human ear is a unique organ that functions on a pair basis, which is located in the very depths of the temporal bone. The anatomy of its structure makes it possible to capture mechanical vibrations of the air, as well as to carry out their transmission through internal media, then transform the sound and transmit it to the brain centers.

According to the anatomical structure, human ears can be divided into three parts, namely the outer, middle and inner.

Elements of the middle ear

Studying the structure of the middle part of the ear, you can see that it is divided into several components: the tympanic cavity, the ear tube and the auditory ossicles. The last of these include the anvil, hammer and stirrup.

Middle ear malleus

This part of the auditory ossicles includes such elements as the neck and the handle. The head of the malleus is connected through the hammer joint to the structure of the body of the incus. And the handle of this malleus is connected with the eardrum by fusion with it. A special muscle is attached to the neck of the malleus, which stretches the eardrum.

Anvil

This element of the ear has at its disposal a length of six to seven millimeters, which consists of a special body and two legs with short and long dimensions. The one that is short has a lenticular process that fuses with the incus stirrup joint and with the head of the stirrup itself.

What else is included in the auditory ossicle of the middle ear?

Stirrup

The stirrup has a head, as well as front and rear legs with a part of the base. The stirrup muscle is attached to its back leg. The base of the stirrup itself is built into an oval-shaped window in the vestibule of the labyrinth. An annular ligament in the form of a membrane, which is located between the support base of the stirrup and the edge of the oval window, contributes to the mobility of this auditory element, which is ensured by the action of air waves directly on the tympanic membrane.

Anatomical description of the muscles attached to the bones

Two transverse striated muscles are attached to the auditory ossicles, which perform certain functions for transmitting sound vibrations.

One of them stretches the eardrum and originates at the walls of the muscular and tubal canals related to the temporal bone, and then it attaches to the neck of the malleus itself. The function of this tissue is to pull the handle of the malleus inward. Tension occurs to the side. At the same time, the tympanic membrane is tensioned and therefore it is, as it were, stretched and concave into the region of the middle ear region.

Another muscle of the stirrup originates in the thickness of the pyramidal elevation of the mastoid wall of the tympanic region and is attached to the foot of the stirrup located behind. Its function is to reduce and remove from the hole the base of the stirrup itself. During powerful oscillations of the auditory ossicles, along with the previous muscle, the auditory ossicles are held, which significantly reduces their displacement.

The auditory ossicles, which are interconnected by joints, and, in addition, the muscles related to the middle ear, fully regulate the movement of air currents at different levels of intensity.

Tympanic cavity of the middle ear

In addition to the bones, a certain cavity is also included in the structure of the middle ear, which is commonly called the tympanic cavity. The cavity is located in the temporal part of the bone, and its volume is one cubic centimeter. In this area, the auditory ossicles are located with the eardrum nearby.

Above the cavity is located which consists of cells that carry air currents. It also contains a kind of cave, that is, a cell through which air molecules move. In the anatomy of the human ear, this area plays the role of the most characteristic landmark in the implementation of any surgical interventions. How the auditory ossicles are connected is of interest to many.

Eustachian tube in human middle ear structure anatomy

This area is a formation that can reach a length of three and a half centimeters, and the diameter of its lumen can be up to two millimeters. Its upper beginning is located in the tympanic region, and the lower pharyngeal mouth opens in the nasopharynx approximately at the level of the hard palate.

The auditory tube consists of two sections, which are separated by the narrowest point in its area, the so-called isthmus. The bone part departs from the tympanic region, which extends below the isthmus, it is commonly called membranous-cartilaginous.

The walls of the tube, located in the cartilaginous region, are usually closed at rest, but when chewing, they can open slightly, and this can also occur during swallowing or yawning. The increase in the lumen of the tube occurs through two muscles that are associated with the palatine curtain. The shell of the ear is lined with epithelium and has a mucous surface, and its cilia move towards the pharyngeal mouth, which makes it possible to ensure the drainage function of the tube.

Other facts about the auditory ossicle in the ear and the structure of the middle ear

The middle ear is directly connected to the nasopharynx through the Eustachian tube, whose primary function is to regulate pressure that comes from outside the air. A sharp laying of human ears can signal a transient decrease or increase in environmental pressure.

A long and prolonged soreness in the temples, most likely, indicates that the ears are currently trying to actively fight the infection that has arisen and thus protect the brain from all sorts of violations of its performance.

Internal auditory ossicle

Among the fascinating facts of pressure, one can also include reflex yawning, which signals that its environment has undergone sharp changes in the human environment, and therefore a reaction in the form of a yawn was caused. You should also know that the human middle ear contains a mucous membrane in its structure.

Do not forget that unexpected, exactly, as well as sharp sounds can provoke muscle contraction on a reflex basis and harm both the structure and the functioning of hearing. The functions of the auditory ossicles are unique.

All of these structures carry such a functionality of the auditory ossicles as the transmission of perceived noise, as well as its transfer from the outer region of the ear to the inner. Any violation and failure of the functioning of at least one of the buildings can lead to the destruction of the hearing organs completely.

Inflammation of the middle ear

The middle ear is a small cavity between the inner ear and the middle ear. The transformation of air vibrations into fluid vibrations is provided by the middle ear, which is recorded by auditory receptors in the inner ear. This happens with the help of special bones (hammer, anvil, stirrup) due to sound vibration from the eardrum to the auditory receptors. To equalize the pressure between the cavity and the environment, the middle ear communicates with the Eustachian tube with the nose. The infectious agent penetrates this anatomical structure and provokes inflammation - otitis media.

Despite the fact that the technology of bone conduction of sound has been known for a long time, for many it is still a “curiosity” that raises a number of questions. Let's answer some of them.

Sport. Models of sports headphones and headsets using this technology are widely known, as this allows athletes to listen to music, talk on the phone, but at the same time control the environment, since the auricles remain open and able to perceive external sounds!

military industry. For the same reason, devices based on bone sound transmission technology are used among the military, as this allows them to communicate, send messages to each other, without losing control of the situation, remaining receptive to the sounds of the outside world.

Diving. The use of bone sound transmission technologies in the "underwater world" is largely due to the properties of the suit, which does not imply the possibility of immersion with other means of communication. For the first time they thought of this back in 1996, what is related patent. And among the most famous pioneer devices of this nature, one can cite as an example Casio developments.

Also, the technology is used in various "household" areas, on walks, while riding a bicycle or in a car as a headset.

Is it safe

In ordinary life, we constantly encounter bone conduction technology when we say something: it is the bone conduction of sound that allows us to hear the sound of our own voice, and, by the way, as it is more “receptive” to low frequencies, it makes it so that our voice is recorded seems to us higher.

The second voice in favor of this technology is its wide application in medicine. Given the fact that the eardrums are a more sensitive organ, the use of bone conduction devices, such as headphones, is even safer for hearing than the use of conventional headphones.

The only temporary discomfort that a person can feel is a slight vibration, which you quickly get used to. This is the basis of the technology: sound is transmitted through the bone using vibration.

open ears

Another key difference from other ways of transmitting sound is open ears. Since the eardrums are not involved in the process of perception, the shells remain open, and this technology allows people without hearing impairments to hear both external sounds and music / telephone conversation!

Headphones

The most famous example of the “household” use of bone conduction technology is headphones, and among them, the and models remain the first and best.

The history of the company suggests that they did not immediately reach a wide audience of users, having cooperated with the military for a long time. Headphones have outstanding characteristics for this class of devices and are constantly being upgraded.

Specifications Aftershokz:

• Speaker Type: Bone Conduction Transducers
• Frequency response: 20 Hz - 20 kHz
• Speaker sensitivity: 100±3dB
• Microphone sensitivity: -40±3dB
• Bluetooth version: 2.1+EDR
• Compatible profiles: A2DP, AVRCP, HSP, HFP
• Communication range: 10m
• Battery type: lithium-ion
• Working time: 6 hours
• Standby: 10 days
• Charging time: 2 hours
• Black colour
• Weight: 41 grams

Can hearing damage

Any headphones can damage your hearing at high volumes. There are much fewer risks with headphones that work on the basis of bone conduction, since the most sensitive organs of hearing are not directly affected.

Is it possible to lean ordinary headphones against the skull and listen to the sound

No, that won't work. All headphones with bone conduction technology work on a special principle when sound is transmitted by vibration, which is why even wired headphones have an additional power source, a built-in battery.

Do headphones replace a hearing aid?

Headphones do not amplify the sound, so they cannot replace a hearing aid, however, in some cases of air conduction disorders of sound, for example, age-related, such headphones can help to distinguish what is heard more clearly.