KR20100122001A - Cochlear implant and sound processing method thereof - Google Patents

Abstract

PURPOSE: By it dissimilar according to the difference of the artificial cochlea and sound signal processing method is the hearing state according to the dysecoia patient, processing the sound the hearing is recovered effectively. CONSTITUTION: The external device(15) processes the received sound as described above as the electric signal by receiving a message the sound signal. The internal device transplanted to internal transfers the electric signal to the contactless. The delivered electric signal as described above is applied through electrode in the boiler of internal to the electronic stimulus.

Description

How to handle cochlear implants and sound signals {COCHLEAR IMPLANT AND SOUND PROCESSING METHOD THEREOF}

The present invention relates to a cochlear implant, and in particular, proposes a cochlear implant that provides sound information to a hearing loss patient by generating an electrical signal close to an actual sound.

The ear consists of the outer ear, middle ear, and inner ear. Sound is transmitted from the outer ear to the eardrum of the middle ear through the vibration of the air and then to the oval window of the cochlea by the oscillation of the auditory ossicles. Produce a signal.

The movement of the cortial membrane produces a receptor potential in hair cells, which is transferred to the spiral ganglion via a dendrite. Spiral ganglion signals stimulate neurons in the auditory nerve and finally deliver them to the cerebrum. Hearing loss often causes problems with the hair cells in the cochlea, in which case sound can be recognized by externally providing electrical signals generated by the hair cells. From this fact, implantable cochlear implants (artificial cochlear implants) have been developed.

Cochlear implants implant a cochlear implanter into the cochlear implant of a patient with high hearing loss, which can detect sound by stimulating the remaining auditory nerve using electrical stimulation. Cochlear implants provide useful hearing for patients with bilateral hearing loss who are not helped by hearing aids, and are considered the most successful neuroadjuvant developed to date.

Since cochlear implants were approved by the US Food and Drug Administration (FDA) in 1984, the scope of application of cochlear implants has recently been expanded worldwide, and multi-channel cochlear implants have been proposed. Multichannel cochlear implants require a plurality of electrodes to individually provide a specific frequency signal that is mapped to a specific location of the cochlear implant. Individual densities of each frequency component are delivered individually to dendrites under damaged hair cells.

1 is a schematic diagram showing the implantation apparatus 10 of a cochlear implant including a conventional multi-electrode. One active electrode 10a and one reference electrode 10b are included, and the end A of the active electrode is spirally formed to facilitate insertion into the cochlea. Referring to FIG. 2, in which the active electrode tip A is enlarged, a plurality of electrodes 15 are distributed, each electrode providing an electrical stimulus of a corresponding frequency at a particular location within the cochlea.

Cochlear implants including such multiple electrodes are not only very long in total length of about 35 mm, but also have a high risk of damaging hair cells while being inserted into the cochlea. The spirally bent electrode tip may rub against the cochlear inner wall, causing damage to hair cells, dendrites, and spiral ganglia, resulting in permanent hearing loss.

Patients implanted with multi-channel cochlear implants show approximately 80% sound discrimination in a quiet environment. However, in places where there are noises or talks by many people, discernment is reduced and music listening is limited, in particular, toneal sensibility is insignificant.

In addition, the existing multi-channel cochlear implants are very expensive, the procedure is very complex and the hygiene risks are large, there are many problems in the application to the actual hearing loss patients.

On the other hand, since the hearing status is different for each deaf patient, individual sound adjustment is very important for hearing recovery through cochlear implants.

The present invention has been made under the foregoing technical background, and an object of the present invention is to provide a cochlear implant accurately transmitting without distortion of sound.

Another object of the present invention is to provide a cochlear implant capable of signal processing adapted to the hearing condition of individual hearing loss patients.

Still another object of the present invention is to provide a cochlear implant that is easy to perform the procedure and minimizes the additional risk during or after the procedure, thereby ensuring safety.

To provide.

In order to achieve the above object, the present invention comprises the steps of receiving a sound signal and processing the received sound as an electrical signal in an external device; Contactlessly transmitting the electrical signal to an internal device implanted in the body; Applying electrical stimulation to organs in the body through the electrode, wherein the electrical signal processing comprises a) electrically converting a sound signal received from the outside; and b) converted electrical signal. Dividing the signal into predetermined frequency bands, c) adjusting the electrical signals separated by the frequency bands, and d) synthesizing the adjusted electrical signals into one electrical signal. It provides a sound signal processing method of cochlear implant.

After the electric signals for each band are synthesized, a full band modulation step including amplitude information and frequency information is performed. In the modulation step, the carrier signal is preferably 20 kHz or more.

The electrical signals separated by the frequency bands are preferably sound processed to match the hearing state of the hearing patient. To this end, the method may further include transmitting sound processing information according to a hearing condition of the hearing loss patient to an external device.

In the present invention, the internal device electrically stimulates the internal organs through a single electrode after receiving the signaled electrical signal through the external device.

According to the present invention, the hearing loss patient who has undergone a cochlear implant provides a soft sound without intermittent sound, and provides a low noise and a close listening sound to real sound. In particular, it is very effective for hearing recovery because the sound processing can be changed according to the difference of hearing condition for each deaf person. In addition, the procedure is easy and easy to manufacture can give more hearing loss patients a chance of hearing recovery.

The present invention is characterized by delivering a synthesized electrical signal to the cochlea of a deaf patient through a single electrode after the sound processing by separating the frequency band.

The cochlear implant according to the present invention will be described with reference to FIG. 3. The external device 200 that receives sound and performs sound processing is mounted at the rear of the ear and transmits an electrical signal to the body transplant apparatus 100 in a non-contact manner. The implantation apparatus 100 is implanted inside the ear canal 310 in the outer ear 300. The reference electrode 120b of the grafting apparatus is inserted into the ear canal skin 330 adjacent to the receiving unit 110, and the active electrode 120a is located in the middle ear through a minute gap between the ear canal skin 330 and the ear bone 320. It extends to the cochlea 360 through the tympanic membrane 340 of 350. An end of the active electrode 120a is connected to contact the spiral ganglion 365 of the cochlea 360.

Referring to FIG. 4, a signal processing state between components of a cochlear implant according to the present invention is schematically illustrated. The external device 200 and the implantation device 100 are contactless by magnets 260 and 114. Combined, and transmit and receive signals wirelessly to each other (I). On the other hand, the transplant apparatus 100 delivers electrical stimulation directly to the cochlea (II). The external device includes a microphone for receiving a sound signal, and a sound processor for separating the received sound signal into a plurality of frequency bands and processing and synthesizing the signals for each frequency band. The modulator performs full-band modulation on the synthesized signal including amplitude information and frequency information. The transmitting unit of the external device and the receiving unit of the implantation device may be formed of a coil.

5 is a schematic view showing the body transplant apparatus. The implantation apparatus 100 includes a receiving unit 110 and an electrode unit for wirelessly receiving an external signal, and the electrode unit includes an active electrode 120a and a reference electrode 120b which are single electrodes. The active electrode 120a may be composed of regions having different thicknesses. The implantation apparatus 100 may include a coil (not shown) for receiving an electrical signal and a magnet (not shown) for contactless coupling by a magnetic force with an external device.

In the cochlear implant according to the present invention, an electrical signal signaled from an external device stimulates the auditory nerve in the cochlea via a single electrode, and in this case, it is not necessary to select the position of the electrode on the specific nerve. Only one frequency can ignite the nerve at the minimum size at which the nerve is stimulated, but it has been shown that one nerve responds at all frequencies if the loudness of the stimulus is sufficient.

The intracellular delivery process of external sounds through the cochlear implant of the present invention is as follows. Sound signals, such as voice or music, are received by an external device, such as a microphone, through a receiving device such as a microphone. Process the received sound as an electrical signal. The processed electrical signal is transmitted in a contactless manner to an implanted implanted device. The electrical signal transmitted to the body applies electrical stimulation to organs in the body through the electrodes of the implantation device, so that the hearing loss patient recognizes the sound.

6 schematically illustrates an electrical signal processing procedure of a cochlear implant according to the present invention.

The sound signal received from the outside is electrically converted through an amplification process (initial signal). The converted electrical signal is separated for each predetermined frequency band. Although there is no particular limitation on the number of band separation in the process of separating the electrical signal by frequency band, it is preferable to separate the signal into at least 4 bands for accuracy of sound control for each hearing loss patient through subsequent signal processing. In this way, by separating the electrical signal for each frequency band, it becomes possible to process the sound considering the characteristics of the hearing loss patient showing a difference in sound recognition for each frequency band.

Electrical signals separated by frequency bands are adjusted for each band (band-by-band signal processing). In this process, gain control, adaptive noise cancellation, and threshold compression are performed for each band. The frequency band adjustment process can be pre-programmed or post-programmed into the sound processor via external software. To this end, the cochlear implant of the present invention may include a terminal for receiving an electrical signal for programming in an external device.

Next, the adjusted electric signals for each band are synthesized into one electric signal. By synthesizing the electrical signals for each frequency band into a single signal, electrical signals in all frequency domains can be transmitted using only a single electrode instead of multiple electrodes.

In the case of a multi-electrode cochlear implant, a sound-processed electrical signal stimulates each of the electrodes to deliver only a specific frequency component necessary for sound recognition. When electrical stimulation is applied to multiple electrodes at the same time, channel interference is generated and it is difficult to accurately recognize sound. Therefore, sequential electrical stimulation is applied to each electrode once. In this case, there is a delay until one sound information is sent and the next sound information is transmitted. As a result, the sound transmitted to the hearing loss patient is interrupted and the sound quality is degraded. In particular, it is not suitable for transmitting an acoustic signal in which a quick tone change occurs, and it is difficult to recognize a language with music and tones.

On the other hand, according to the present invention, the electrical signal transmitted to the hearing loss patient is continuous and can provide sound information that is like real sound.

Finally, the synthesized signal is amplitude modulated using a fixed carrier signal of 20 kHz or higher. The frequency range of the modulated signal is very important for hearing loss patients to hear sound in the range of 200 to 8000 Hz, which is required for speech recognition, and 200 to 20,000 Hz, which is an audible frequency band. For this reason, in the present invention, modulation is performed using a carrier signal of 20 kHz or more, and more preferably, a carrier signal of 26 to 32 kHz is suitable.

The sound processing method of the cochlear implant according to the present invention converts a sound signal into an electrical signal and provides sound information very similar to the first received sound signal to the hearing loss patient through various sound processing.

In the case of conventional cochlear implants, due to simple signal processing without separation of frequency bands or signal adjustment for each band, the peak clipping not only has a small dynamic range of about 15 dB but also limits the signal size to a certain level. This was terrible. For example, in the conventional cochlear implant, as shown in FIG. 7B, a waveform in which the peak clipping occurs is present. On the other hand, the cochlear implant of the present invention enables accurate reproduction of sound by generating a signal waveform very close to the original sound signal waveform as shown in FIG. 7C.

In addition, in the conventional cochlear implant, the waveform distortion is severe, the noise is severe and the sound quality is deformed, whereas the cochlear implant according to the present invention was confirmed to generate a signal waveform very similar to the original sound signal.

The cochlear implant of the present invention generates an electric signal capable of accurate sound transmission even when using only a single electrode. Therefore, not only is it more effective in hearing recovery of a hearing loss patient, but the cochlear implant procedure is simple and easy to prevent the risk of damage to auditory cells that may occur during the cochlear implant procedure.

Clinical trials of the hearing loss implanted with the cochlear implant of the present invention, it was confirmed that the recovery of the excellent sound recognition ability is possible.

Referring to the graph of FIG. 8, the result of comparing the pre-procedure and the listening ability of the 25 patients undergoing the listening training for 24 weeks after the cochlear implant procedure is shown. Pure-tone audiometry (PTA) in the 500-6000 Hz range showed that the threshold level was above 100 dB but recovered to 40 dB.

9A and 9B show a result of comparing word recognition with pre-treatment in 25 patients who have undergone listening training for 24 weeks after cochlear implant surgery. Comparing the 12th week and the 24th week, it can be seen that the word recognition ability is greatly improved, and after 24 weeks, scores of up to 72% and an average of 33% are obtained.

Meanwhile, FIGS. 10A and 10B show a result of comparing the sentence recognition ability with the preoperative procedure for 25 patients who have undergone 24 weeks of listening training after the cochlear implant procedure. After 24 weeks, the average is 91%. It can be seen that the excellent score of 40% was obtained.

Through these clinical results, it was confirmed that the cochlear implant of the present invention can greatly contribute to the recovery of the sound recognition ability of the hearing loss patient as well as the ease of the procedure, and can greatly shorten the sound recognition training process for each patient. .

The present invention has been exemplarily described through the preferred embodiments, but the present invention is not limited to such specific embodiments, and various forms within the scope of the technical idea presented in the present invention, specifically, the claims. May be modified, changed, or improved.

1 is a schematic diagram showing an internal implantation apparatus of a conventional cochlear implant.

FIG. 2 is an enlarged view of portion A of FIG. 1; FIG.

Figure 3 is a schematic diagram showing the implanted cochlear implant of the present invention.

4 is a schematic diagram showing signal processing between an external device and an internal transplant apparatus;

5 is a schematic view showing the structure of the body transplant apparatus.

Figure 6 is a schematic diagram showing a signal processing process of the cochlear implant of the present invention.

7A to 7C are graphs comparing waveforms after initial signal and signal processing.

Figure 8 is a graph showing the results of the labial hearing after cochlear implant surgery.

9A and 9B are graphs showing word recognition test results after cochlear implant procedures.

10a and 10b are graphs showing a sentence recognition test result after cochlear implant surgery.

*** Explanation of symbols for the main parts of the drawing ***

100: implantation device 120a: active electrode

120b: reference electrode 200: external device

Claims (12)

Receiving a sound signal and processing the received sound as an electrical signal at an external device; Contactlessly transmitting the electrical signal to an internal device implanted in the body; Applying electrical signals transmitted to the organs within the body through the electrodes, The electrical signal processing step a) electrically converting a sound signal received from the outside, b) separating the converted electrical signal by a predetermined frequency band; c) adjusting electrical signals separated by frequency bands; d) synthesizing the adjusted electrical signals for each band into one electrical signal. Method of processing sound signal of cochlear implant. The method of claim 1, wherein the synthesized signal is subjected to a full-band modulation step including amplitude information and frequency information. The method of claim 1, wherein the electrical signal is separated into at least four frequency bands. The method of claim 1, wherein the electrical signals separated by the frequency bands are sound processed to match the hearing state of the hearing patient. The method according to claim 4, further comprising transmitting sound processing information according to the hearing condition of the hearing patient to an external device for the sound processing. The method of claim 1, wherein the synthesized electrical signal is modulated with a carrier signal of 20 kHz or more. The method of claim 1, wherein the internal device electrically stimulates the organs through the single electrode. An external device that receives and electrically processes a sound signal, An internal device coupled to the external device in a non-contact manner to receive an electrical signal generated from the external device, The external device includes a signal processor that separates the received sound signal into a plurality of frequency bands, and processes and synthesizes a signal for each frequency band. Cochlear implant. The cochlear implant of claim 8, further comprising: a modulator configured to perform full-band modulation on the synthesized signal including amplitude information and frequency information. 10. The cochlear implant according to claim 9, wherein the modulator has a carrier signal frequency of 20 kHz or more. The cochlear implant of claim 8, wherein the external device includes an information receiver configured to receive sound processing information according to a hearing condition of the hearing patient. 9. The cochlear implant of claim 8, wherein the internal device includes a single electrode that electrically stimulates the organs of the body with an electrical signal received from an external device.

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