KR20060000025A - Cochlear implant having noise reduction function and method for reducing noise - Google Patents

Abstract

The present invention uses a plurality of microphones for receiving an external sound to generate an analog sound signal, a front end for converting an analog sound signal into a digital sound signal, and extracting a digital voice signal from the digital sound signal using a preset signal processing algorithm. Receiving from an in vitro device and an in vitro device comprising a signal processor, a stimulus request signal generator for generating a stimulus request signal corresponding to a digital voice signal, and a transmitter for converting the stimulus request signal to a preset communication method and transmitting the signal to a body device The present invention relates to a cochlear implant and a noise canceling method having a noise canceling function including an internal device that stimulates the auditory nerve to correspond to a stimulus request signal, so that a hearing aid wearing patient can be clearly provided with only a voice signal even in a noisy environment.

Cochlear implant, hearing aid, noise, hearing patient,

Description

Cochlear implant having noise reduction function and method for reducing noise             

1 is a block diagram showing the configuration of a conventional cochlear implant system.

2 is a view showing the mounting state of the cochlear implant system.

Figure 3 is a block diagram showing the configuration of the cochlear implant system according to an embodiment of the present invention.

Figure 4 shows the appearance of the cochlear implant system according to an embodiment of the present invention.

5 is a diagram illustrating a voice signal and a noise signal.

6 is a diagram illustrating a noise-voice mixed signal and a noise-free speech signal according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

135: front end

140: frequency analysis unit

145: selection unit

150: signal size control unit

155: transmission unit

170: receiver

175: control unit

180: back end

185 electrode

300: Cochlear Implant System

310 outside the body

320: inside the body

330a, 330b: microphone

340: signal processing unit

The present invention relates to a cochlear implant and a noise canceling method having a noise canceling function. In particular, the present invention relates to a noise canceling function that allows a hearing patient to hear a speech more clearly in an environment with high ambient noise. The present invention relates to a cochlear implant and a noise removing method.

In general, the human ear is divided into three parts: the outer ear, middle ear, and inner ear. The path through which sound can be heard from the human ear is as follows. Sound vibrations are collected in the ear canal and transmitted along the ear canal to the eardrum. The ear canal is a type of resonance tube that is blocked by one eardrum, and the vibrations of the eardrum are transmitted to the inner ear through the three osseous bones (ie, hammerbone, anvil bone, and ring bone) in the middle ear. The oscillations of the osseous bone are transmitted to the cochlea in the inner ear through the pedestal of the ring bone. The cochlea (Cochlea) is the organ responsible for the human hearing function. It is shaped like a snail about 3.5 cm long and has a shape of a tube about two and a half curls long. Lymphatic fluid inside the cochlea moves, and thousands of tiny hair cells in the middle layer of the cochlea detect the vibrations of the lymphatic fluid and convert the stimulus into an electrical signal. The electrical signal is then transmitted to the brain through the auditory nerve, which allows a person to hear sounds.

Hearing aids or cochlear implants may be required for patients with impaired hearing or in hearing loss. Hearing loss can be largely divided into conductive hearing loss and sensorineural hearing loss. Preneural hearing loss is a hearing loss caused by the disease of the outer ear and middle ear. In the case of nonnegative hearing loss, the hearing nerve is not damaged, and hearing loss can be compensated by wearing hearing aids. However, sensorineural hearing loss is a hearing loss caused by abnormalities of the auditory nerve. Auditory nerve abnormalities may be caused by genetic or pathological factors. Sensorineural hearing loss cannot be compensated for hearing loss by wearing hearing aids. This is because the sound information cannot be properly transmitted from the cochlea to the brain. That is, in the case of sensorineural hearing loss, inner hair cells in the cochlea do not function, and therefore, auditory nerves are not excited even when external sounds are transmitted to the cochlea via the outer and middle ear. Therefore, since no information about external sound stimulation is transmitted to the brain, the patient with sensorineural hearing loss cannot hear the sound. Cochlear Implants have been developed worldwide to restore hearing in patients with sensorineural hearing loss.

Cochlear implants have been developed for hearing compensation in patients with sensorineural hearing loss or hearing impairment due to damage to the hearing cells of the inner ear. The structure of the cochlear implant device is composed of an extracorporeal part and an internal part which is inserted through surgery to the temporal bone area of the patient. The procedure of cochlear implant is as follows. First, the patient's yangdong (or yangdol) is ground and exposed to the cochlea's round window. Subsequently, a cochlear electrode of a very thin and long structure form having a length of about 2 mm to about 2.5 mm is inserted into the cochlea. The cochlear implant body consists of a microphone, speech processor and transmitter, and the body portion consists of an induction coil and an electrode. The cochlear implant outside analyzes the external sound input through the microphone through the speech processor and transmits electrical stimulation information to the cochlear implant through the transmitter. At this time, the communication between the outside and the inside of the body is made by RF (Radio Frequency) communication. The cochlear body electrically stimulates the auditory nerve to correspond to the received electrical stimulation information.

This cochlear implant is intended to deliver clear speech to deaf patients. However, the conventional cochlear implant stimulates a noise component even in an environment with strong ambient noise, and thus, it is difficult for an auditory patient to recognize speech accurately.

Accordingly, an object of the present invention for solving the above problems is to provide a cochlear implant and a noise canceling method having a noise canceling function so that a hearing aid wearing patient can be clearly provided only a voice signal even in a noisy environment.

It is another object of the present invention to provide a cochlear implant and a noise canceling method having a noise canceling function capable of providing a high noise attenuation effect even in a noise environment with a signal processing algorithm.

In order to achieve the above objects, according to an aspect of the present invention, in the in vitro device of the cochlear implant system comprising an extracorporeal device and an internal device for stimulating the auditory nerve corresponding to the stimulus request signal received from the extracorporeal device, A plurality of microphones that receive a sound of an audio signal to generate an analog sound signal, wherein the analog sound signal includes an analog voice signal and an analog noise signal; A front end for converting the analog sound signal into a digital sound signal; A signal processor extracting a digital voice signal from the digital sound signal using a preset signal processing algorithm; A stimulus request signal generator for generating a stimulus request signal corresponding to the digital voice signal; And a transmission unit for converting the stimulus request signal to correspond to a preset communication method and transmitting the stimulus request signal to the internal device.

The plurality of microphones have different directing directions from each other, and each of the microphones includes at least one of an omnidirectional sound input unit and a directional sound input unit.

The preset communication method may be a radio frequency (RF) transmission scheme of the stimulus request signal. Alternatively, the preset communication method may be an infrared communication method.

The signal processing algorithm may be an independent component analysis (ICA) algorithm.

The internal device includes a receiver, a request stimulus generator and a stimulus output unit, the receiver receives a signal from the transmitter and demodulates the request stimulus signal, and the request stimulus generator outputs a stimulus corresponding to the request stimulus signal. Generating a signal to stimulate the auditory nerve through the stimulus output unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, the same reference numerals will be used for the same means regardless of the reference numerals in order to facilitate the overall understanding.

1 is a block diagram showing the configuration of a conventional cochlear implant system, Figure 2 is a view showing the mounting state of the cochlear implant system.

Referring to FIG. 1, the conventional cochlear implant system 100 includes an external part 110 and an internal part 120. The block diagram of FIG. 1 is for explaining the configuration and operating principle of the conventional cochlear implant system 100, and the detailed configuration of the actual conventional cochlear implant system 100 may be somewhat different from that of FIG. 1.

The external unit 110 includes a microphone 130, a front end 135, a frequency analyzer 140, a digital signal generator 145, and a signal amplitude controller Amplitude Mapping) 150 and a transmitter 150.

The microphone 130 receives an external analog sound signal (for example, voice or sound) and transmits it to the front end 135, and the front end 135 optimizes the input analog sound signal to provide a digital sound signal. In addition, the frequency analyzer 140 analyzes the digital sound signal received from the front end 135 for each frequency. The selection unit 145 samples and selects a signal analyzed for each frequency, and adjusts the digital sound signal selected by the signal size adjusting unit 150 to the psychoacoustic size of the hearing loss patient. Thereafter, the transmitter 155 encodes the scaled digital sound signal, generates an RF signal corresponding to the electrical pulse, and transmits the RF signal to the body 120. The RF (Radio Frequency) communication method is used to transmit and receive signals between the body 110 and the body 120. At this time, the power signal is transmitted to the body 120 together.

The body 120 includes a receiver 170, a controller 175, a back end 180, and an electrode 185.

The receiver 170 receives an RF signal from the transmitter 155 of the body 110 and decodes the received RF signal to extract a power signal and a sound signal.

The controller 175 generates a stimulus signal having an optimized electrical stimulation pattern (for example, an electrode channel, a stimulus mode, a stimulus size, and a stimulus period) using the sound signal and transmits the stimulus signal to the back end 180. The power used at this time may be obtained from the RF signal received by the receiver 170. The back end 180 actually causes the electrode 185 to electrically stimulate the auditory nerve according to the electrical stimulation pattern determined by the controller 175.

An exemplary view of a hearing patient equipped with the conventional cochlear implant system 100 shown in FIG. 1 is illustrated in FIG. 2.

The conventional cochlear implant system 100 will be briefly described as a method of processing the input analog sound signal so that the hearing loss patient can recognize.

First, the microphone 130 receives an external analog sound signal and converts the analog sound signal into an electrical signal. The converted electrical signal is encoded by the frequency analyzer 140 to the transmitter 155 in the form of an electrical pulse. The encoded electrical pulse is transmitted by the transmitter 155 to the receiver 170 of the body 120 through an RF communication method. The electrical pulse received through the receiver 170 is transmitted to the electrode 185 through the controller 175 and the back end 180. The auditory nerve receives a minute electric pulse from the electrode 185 and delivers it to the brain, which interprets the signal as sound.

As described above, the external unit 110 of the conventional cochlear implant system 100 adopts a method of analyzing only the input external sound signal for each frequency and transmitting it to the internal unit 120. However, this method is a source of discomfort to the hearing patient because the external noise is not properly removed when the external noise is strong, but even the noise component is electrically stimulated by the auditory nerve.

Figure 3 is a block diagram showing the configuration of the cochlear implant system according to an embodiment of the present invention, Figure 4 is a view showing the appearance of the cochlear implant system according to an embodiment of the present invention. 5 is a diagram illustrating a speech signal and a noise signal, and FIG. 6 is a diagram illustrating a noise-voice mixed signal and a speech signal from which noise is removed according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a cochlear implant system 300 having a noise canceling function according to the present invention includes an external part 310 and an internal part 320.

The external unit 310 may include two or more microphones (however, the number of microphones may be implemented in two or more, but assuming two cases, the first microphone 330a and the second microphone 330b). And a front end 135, a signal separation unit 340, a frequency analyzer 140, a selection unit 145, a signal amplitude adjusting unit 150, and a transmission unit 155.

The first microphone 330a and the second microphone 330b are independently provided in the forward direction and the rear direction, respectively, to receive an external analog sound signal. FIG. 4 illustrates an external view when the first microphone 330a and the second microphone 330b are provided in different directions, respectively. As shown in FIG. 4, the first microphone 330a and the second microphone 330b each have different directing directions, and each microphone may have a directional sound input unit and / or an omnidirectional sound input unit.

The first microphone 330a and the second microphone 330b transmit the input analog sound signal to the front end 135. The front end 135 optimizes the received analog sound signal. That is, the front end 135 amplifies the input analog sound signal to a predetermined size, and then converts the amplified analog sound signal into a digital sound signal.

Thereafter, the signal processor 340 separates the digital sound signal into a digital voice signal and a digital noise signal, and provides the digital voice signal to the frequency analyzer 140. Hereinafter, a method of separating the digital sound signal into the digital voice signal and the digital noise signal by the signal processor 340 will be briefly described.

The signal processor 340 may use various signal processing methods to separate the digital sound signal. However, the signal processor 340 will be described with reference to a method of extracting a voice signal using an independent component analysis (ICA) algorithm.

  Independent element analysis (ICA) is a technique for separating statistically independent signals from linearly mixed signals. Signal sources input through the two microphones 330a and 330b may be expressed by Equation 1 below.

Here, s1 (t) and s2 (t) are independent signals and mean signal sources input through the microphones 330a and 330b, and x1 (t) and x2 (t) are a ₁₁ , a ₁₂ , Signals made in a linear combination by the weight of a ₂₁ , a ₂₂ . In other words, each of the signal sources are randomly mixed into the acoustic field and input into the microphone. This process is expressed by multiplying each signal source by a weight.

For example, suppose there are two microphones and two male and female voice signals.

At this time, if the microphone is set to the recording state and the male and the female begin to speak at the same time, the signal obtained in the microphone 1 and the microphone 2, respectively, is a voice signal in which the male and female voices are properly mixed. Each voice is input into the microphone through such a process, that is, a process of random mixing in the acoustic field. The signal considered in the ICA algorithm is to separate the male and female voices with only the signals detected by the sensor. In this case, the mixing process in the acoustic field is regarded as a matrix having elements a ₁₁ , a ₁₂ , a ₂₁ , and a ₂₂ . Therefore, as shown in Equation 1, the signal obtained by the microphone can be described as the product of the original signal and the weight matrix.

  As such, the analog sound signal is transmitted to the front end 135 through the microphones 330a and 330b in the form of a sum of the signal sources and the weights. If this process is generalized and established as a statistical model, it can be expressed as Equation 2 below.

Here, A is an unknown reversible matrix and is called a mixing matrix. The ICA algorithm recovers the sound source signal by finding the inverse of the mixed action A using only the signal X measured through an input device such as a microphone. Therefore, the separation matrix W, which is the inverse of the mixing matrix A, must be estimated, which can be expressed as Equation 3 below.

Here, it is assumed that the signal sources are independent of each other in order to estimate the separation matrix W. That is, it is assumed that the original signal from one sound source does not mutually affect the original signal from another sound source.

  Various methods have been proposed to date to estimate the aforementioned separation matrix W. Such methods include, for example, entropy maximization method, information maximization method, negentrophy maximization method, mutual information minimization method, and maximum likelihood estimation method. A method of estimating the separation matrix W by the double entropy maximizing method is given by Equation 4 below. Of course, it is obvious that the method of estimating the separation matrix W is not limited to the entropy maximizing method.

  The speech signal separator 225 may extract the speech signal (ie, separating the speech signal and the noise signal) from the analog sound signal in which the speech signal and the noise signal are mixed by using Equation 4 described above.

In FIG. 5, a voice signal 510 and a noise signal 520 are shown, and in FIG. 6, a noise-noise voice signal using the noise-voice mixed signal 610 and the cochlear implant system 300 according to the present invention ( 620 is shown.

Referring to FIG. 6, when using the cochlear implant system 300 according to the present invention, it will be readily understood that an auditory patient can recognize a clearer speech signal.

Referring back to FIG. 3, the voice signal extracted through the above-described process is analyzed for each frequency in the frequency analyzer 140. In addition, the signal analyzed for each frequency is sampled and selected by the selection unit 145, and the size of the signal is adjusted by the signal size adjusting unit 150 to match the psychoacoustic size of the hearing loss patient. Thereafter, the transmitter 155 generates an RF signal corresponding to the processed signal and transmits the RF signal to the body 320. Of course, the signal transmission and reception between the body 110 and the body 120 may be performed by an infrared communication method in addition to the RF communication method. If the infrared communication method is used, the external unit 310 may further include a light source diode such as, for example, a light emitting diode (LED) or a laser diode (LD), and the internal unit 320 may include light. It may further include a photo detector for converting the signal into an electrical signal.

Since the configuration of the internal part 320 and the function of each component are as described above with reference to FIG. 1, description thereof will be omitted.

As such, the present invention relates to a noise reduction method of a cochlear implant system that enables hearing patients to hear speech better even in an environment with strong ambient noise. Accordingly, those skilled in the art will readily appreciate that a configuration in which a plurality of microphones and signal processing units are provided to extract a digital voice signal from which noise is removed may be implemented in a variety of configurations different from those illustrated in FIG. 3. .

As described above, the cochlear implant and the noise canceling method having the noise canceling function according to the present invention enable the hearing aid wearing patient to be clearly provided only the voice signal even in the noise environment.                     

In addition, the present invention may be provided with a signal processing algorithm to provide a high noise reduction effect even in a noisy environment.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

Claims (6)

An extracorporeal device in a cochlear implant system comprising an extracorporeal device and an intracorporeal device that stimulates the auditory nerve to correspond to a stimulus request signal received from the extracorporeal device. A plurality of microphones for receiving an external sound and generating an analog sound signal, wherein the analog sound signal includes an analog voice signal and an analog noise signal; A front end for converting the analog sound signal into a digital sound signal; A signal processor extracting a digital voice signal from the digital sound signal using a preset signal processing algorithm; A stimulus request signal generator for generating a stimulus request signal corresponding to the digital voice signal; And A transmitter for converting the stimulus request signal to correspond to a preset communication method and transmitting the signal to the internal device In vitro device of the cochlear implant system comprising a. The method of claim 1, The plurality of microphones have different directing directions from each other, each microphone having at least one of an omnidirectional sound input unit and a directional sound input unit; In vitro device of cochlear implant system characterized in that. The method of claim 1, The preset communication method is a radio frequency (RF) transmission scheme for the stimulus request signal. In vitro device of cochlear implant system characterized in that. The method of claim 1, The preset communication method is an infrared communication method In vitro device of cochlear implant system characterized in that. The method of claim 1, The signal processing algorithm is an independent component analysis (ICA) algorithm. In vitro device of cochlear implant system characterized in that. The method of claim 1, The internal device includes a receiver, a request stimulus generation unit and a stimulus output unit, The receiver receives a signal from the transmitter and demodulates the request stimulus signal, and the request stimulus generator generates an output stimulus signal corresponding to the request stimulus signal to stimulate the auditory nerve through the stimulus output. In vitro device of cochlear implant system characterized in that.

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