Recently, implantable hearing aids have become an alternative to traditional hearing aids. Fully implantable hearing aids, i.e., without an external component, are already in use in Europe and will soon be cleared by the FDA for use. Conventional hearing aids transmit sound waves through the external ear canal, tympanic membrane, and auditory chain to the inner ear via natural transmission pathways. Implantable hearing aids, on the other hand, stimulate the middle ear by vibrating the auditory chain directly or partially through the middle ear. This type of implantable hearing aid differs from other implantable hearing aids, either through a bone-conduction stimulation device (e.g. Baha) or stimulation that does not involve the middle ear (e.g. Gold RetroX). CE The first partially approved implantable device is the Vibrating Sound Bridge (VSB), the vibrating MEI, which is based on a cylindrical regulator known as the Floating Mass Transducer (FMT), which moves the iron mainly by means of electromagnetism. The principle of action equals reaction and it only needs to be connected to the auditory chain and not to the skull. This feature allows the implant to be placed in a growing skull, so CE decided to include children in the implantable population. The passive implant has a receiver coil that receives the energy and acoustic signals from the external device containing the battery. There are no components outside the body, so it requires a transdermal rechargeable implantable battery and an implantable microphone. A receiver coil is located in the ceramic slot, which receives evoked potentials and transmits the data to accessories and remote control. The subcutaneous microphone is placed in the external ear canal near the tympanic membrane. A piezoelectric transducer is fixed to the surface of the skull and transmits vibrations to the auditory bone via a rod connection. At first, a laser is used to drill a small hole in the body of the anvil and then the rod is fixed to the small hole, but in later implantations, the rod is gradually replaced by a clip. The position of the microphone is unusually close to the tympanic membrane, so acoustic feedback is generated when the sound is transmitted to the tympanic membrane, and it is likely to interfere with the auditory chain. It can be seen in Figure 3B that it has very little range of application, so it led to the disappearance of the device from the market. The partially implanted middle ear transducer (MET), Otologics LLC, has a similar configuration to the VSB, but it uses an electromagnetic transducer. the TICA is fixed with a bone-fixed transducer by a connection that manages the transducer to the anvil bone. Intraoperatively, the transducer is carefully adjusted in the mid-axis direction and the laser-perforated anvil is monitored through the load, thus avoiding overloading the transducer or breaking the auditory chain. Proper adjustment protects normal sound conduction, and when the device is turned off, conduction deafness associated with the implant does not impair normal hearing. The IS-1 connector between the transducer and the implant does not have to touch the middle ear, but allows late exchange of the processor. Figure 3B shows the range of adaptation of the MET. After receiving CE marking in 2001, Otologics developed the fully implantable system Carina (Figure 2) based on the MET transducer. The device is implanted with a sound processor, a rechargeable battery and a transfer coil in the slot. The transfer coil is used for charging and remote control, as well as for downloading accessory parameters and rehearsing the processor. This feature allows upgrading the hardware within the limits of the DSP without surgical intervention. With the IS-1 connector, the device can be replaced or upgraded, i.e., from a semi-implanted MET to a Carina or vice versa. For example, in a case of ongoing hearing loss, a MET is required when results greater than 10 dB are needed, and a fully implanted exchange is also required when the rechargeable battery is depleted, if charged daily for about 8 years. The implantable microphone is permanently connected by a wire and must be exchanged with the processor. Initially, the microphone was located above the earlobe, but had muscle movement problems, since then the microphone is now located percutaneously behind the ear, although soft tissue problems can occur in the placement. In contrast to TICA and Carina, both of which have demonstrated the feasibility of implantable microphones, Esteem ,Envoy Medical uses the eardrum as a natural microphone membrane. It has a piezoelectric transducer that collects sound from the anvil and transmits the amplified vibrations to the stapes through its piezoelectric actuator. Because the direct mechanical connection of the transducer and driver can lead to acoustic feedback, this device requires an interruption of the auditory chain, and when the device is turned off, conductive deafness occurs in all cases. The device does not utilize repeated rechargeable batteries, but rather has a battery device that has a life span of several years at which time it needs to be surgically replaced. In this case, the sensor and driver can be disconnected from the battery-operated processor without contacting the middle ear or minimizing the risk of surgery. Although the initial range of adaptation was narrow, the improved version of Esteem covers a wider range. Concept The most obvious difference between a partially implanted and fully implanted device is that the former has an extracorporeal part that includes the microphone, processor and battery (e.g. VSB). The possibility of full implantation implies the need for an implantable microphone, a wireless battery and data transmission control accessories. For implantable microphones, there are two competing concepts: a) subcutaneous microphones (TICA, Carina); and b) the tympanic membrane as a sound collector (Esteem). We know that the environment is dominated by a cranially relevant transformation function that can be used to locate the directional source, whereas a subdermal microphone located on the side of the head does not protect the acoustic properties. It has been shown that the advantage of both devices to take advantage of acoustic properties is weak, and therefore, any implantable device that wants to have directionality is impossible. So both devices utilize sound collectors located near or on the tympanic membrane requiring interruption of the auditory chain to avoid acoustic feedback. Another feature is the use of acoustic modulator technology and the distinction between piezoelectric and electromagnetic modulators. Because of the low amplitude, more energy is needed to start, and at the same time, the electromagnetic regulator needs to consume more energy. The regulator technology is closely related to the battery, as low consumption is required to utilize non-rechargeable batteries. Therefore, neither Esteem’s electromagnetic regulator nor the digital processor can be connected to non-rechargeable devices that require analog and piezoelectric technology. As a result, digital sound processing technology, which is common in conventional hearing aids, cannot be implemented in this device, nor can changes be uploaded in hardware in the DSP program. Implantable hearing aids began as a treatment for simple sensorineural deafness, but have now evolved to be used in cases with damage to the middle ear. It has been suggested to stimulate the round window before the implant has entered clinical operation, but it took about 10 years for the method to be experienced in humans. There have been many successful trials of activated implants attached to conventional prostheses since then. The effectiveness of IMEHDs adapted to the middle ear is emphasized: they have the potential to replace middle ear function while compensating for SNHL. Although Baha has the potential to overcome acoustic resistance, provide restricted separation of the two ears, and reduce the temporal difference to the sound source. For mixed deafness, direct acoustic stimulation was initially developed to replace middle ear function. At first, the device was supported by a partnership between Cochlear and Phonak, and now, no residual middle ear structures are required and the stimulation of the cochlea is comparable to a standard stapedial pistonectomy. The device will be adequate in the near future for deafness that is difficult to manage in combination with vocalization, and it is envisaged that surgical management of middle ear reconstruction will be a successful treatment in most cases, but will also lead to inadequate results in the shared state. Therefore, we conclude that implantable hearing aids are becoming more and more necessary and that irreplaceable devices by shunting and replacing the middle ear have become real.