CN103356308B - Array fiber opto-acoustic bionic ear device and signal conversion method - Google Patents

Abstract

The invention specifically discloses an array fiber laser induced auditory device and an optical signal conversion method. The device includes a sound signal processor, an array data controller, a laser modulation driver, a laser fiber array, and a fiber collimator. The laser modulation driver is responsible for converting the multiple electrical signals output by the voice processor into corresponding optical signals. The voice processor is connected to the array data controller, and the array data controller controls each electrical signal separately and is connected to the corresponding laser modulation driver, each laser modulation driver is connected to the optical fiber array, and the optical fiber array is connected to each corresponding optical fiber collimator Connected, and finally each optical signal output irradiates the corresponding position of the auditory nerve of the organism. Wherein the optical signal output of each port of the laser fiber array corresponds to the audio frequency band divided by the logarithmic scale, that is, each optical fiber signal output corresponds to a corresponding audio frequency band signal.

Description

Array fiber laser induced hearing device and optical signal conversion method

technical field

The invention relates to the application field of optical fiber sensing and photoelectric technology, in particular to an array optical fiber laser-induced auditory device and an optical signal conversion method.

Background technique

The sensory sound of the inner ear of the auditory system has the characteristics that the topological structure of the cochlea and the frequency components of the sound correspond to each other, and a large number of auditory cells (also known as hair cells) are distributed in the interior according to the corresponding positions, and their functions are similar to "sensors" for sensing audio components. It is these hair cells and the auditory nerve at the back end that are connected to each other to complete the transmission of sound information to the functional areas of the brain. The existing artificial auditory reconstruction device - Cochlear Implant (often abbreviated as CI), is based on the above principles. CI can better solve the problem of speech sound information transmission and perception, and is used for severe and above deafness. Patient clinical treatment restoration. However, studies have shown that such devices have many problems in perceiving more complex and richer acoustic information (such as various musical tones).

The current cochlear implant products use metal electrodes (such as silver electrodes) to be inserted into the cochlea, and a number of electrode points are distributed on them corresponding to the corresponding frequency bands, and the sensorineural auditory nerves in the cochlea are stimulated by electrode current to transmit the acoustic information of the corresponding frequency bands. Due to the diffusion of the electric field in the electrode current, the synchronous excitation density of the stimulating current in the cochlea space is limited. Either the sound spectrum signals that originally appeared synchronously are released at intervals in time, or only the electrodes that are spaced apart in space can be selected. The spectral signals are released at the same time, so as to reduce the electric field interference caused by the simultaneous release of adjacent electrode currents. Therefore, the adjustments made when these electrical signals are excited cause some distortions in the original spectrum array structure of the sound during the stage of stimulating the auditory nerve. For speech signals whose time and spectral structure change slowly, the influence may be limited, and it will not significantly affect the recognition and understanding of the transmitted speech, but for music signals whose spectral structure and time relationship change more closely, this distortion It will lead to the confusion of the acoustic information, making it difficult to obtain pleasant sound effects.

Contents of the invention

In order to solve the problems in the prior art, the invention specifically discloses an array fiber laser induced hearing device and a signal switching method.

The technical scheme that the present invention adopts is as follows:

An array fiber laser induced auditory device, including a speech processor, an array data controller, a laser modulation driver, a laser fiber array, and a fiber collimator;

The speech processor converts the sound signal into an electrical signal and transmits it to the array data controller;

The array data controller separately controls each electrical signal to be connected to the corresponding laser modulation driver;

The laser modulation driver is responsible for converting the multi-channel electrical signals output by the voice processor into corresponding optical signals; wherein one electrical signal corresponds to one optical signal;

The laser fiber array transmits each optical signal to a fiber collimator; and one optical signal corresponds to a fiber collimator;

The fiber collimator focuses each optical signal and outputs a laser beam.

The optical signal output of each port of the laser fiber array corresponds to the audio frequency band divided by the logarithmic scale, that is, each optical fiber signal output corresponds to a corresponding audio frequency band signal.

The laser modulation driver includes multiple laser modulation drive units, the number of the laser modulation drive units is the same as the number of fibers in the fiber array, and the parameters of each laser can be controlled independently and in parallel.

The multi-channel laser modulation drive unit includes a power supply unit, an LD controllable constant current drive unit, a timing control unit, a MOSFET high-speed switch circuit, and an LD laser (semiconductor laser).

The power supply unit converts 220V AC mains power into DC power suitable for the LD controllable constant current drive unit through an AC-DC converter, and the power supply unit is connected with the LD controllable constant current drive unit.

The LD controllable constant current drive unit, under the power supply of DC voltage, adopts a synchronous step-down high-current drive, and provides the required current to the LD laser through a current amplification circuit composed of a Darlington tube to drive the laser to emit light. And the driving current changes with the amplitude of each signal output by the previous array data controller;

The timing control unit controls and generates corresponding pulse sequence signals with controllable pulse repetition frequency and pulse width according to the timing relationship of channel electrical signals;

The MOSFET high-speed switching circuit is connected to the LD laser, and the drive current generated by the LD controllable constant current source drive unit is used as input, and the timing signal generated by the timing control unit is matched to make the MOSFET field effect tube quickly turn on and off, and control The excitation current signal output to the LD laser;

The LD laser is used as a light source for generating optical signals, and the wavelength of the light source can be selected.

A signal conversion method of an array fiber laser induced hearing device, comprising the steps of:

Step 1. After the voice processor transforms, divides, and extracts the collected broadband sound signals, it forms an array electrical signal with an acoustic information structure. The frequency bands of the electrical signals of each channel must conform to the auditory characteristics of the human ear, and are divided according to the logarithmic scale. The electrical signal of each channel corresponds to one optical signal in the laser fiber array;

Step 2: The array data controller converts the electrical signals of the acoustic information structure into electrical signals for driving the LD laser in each single channel, and these electrical signals correspond to the control parameters of the driving light source;

Step 3. Each laser modulation drive unit adjusts and controls the time, strength and duration of the light pulse generation according to the time of occurrence of the electrical signal, the magnitude of the amplitude, and the frequency band position. The LD controllable constant current drive unit controls the intensity of the light pulse. The MOSFET high-speed switching circuit is responsible for converting the continuous light emitted by the LD laser into pulsed light corresponding to the electrical signal of the channel, so as to modulate the sound information carried by the electrical signal of each channel to the optical signal corresponding to each channel of the fiber array. These optical signals are still Audio information that maintains logarithmic scale frequency intervals;

Step 4. The optical signals of each channel are output by the optical fiber array, and the optical signals of each channel can be transmitted synchronously, and have mutual independence and stability;

Step 5: At the corresponding irradiation position, focus the output laser beam through the fiber collimator.

The speech processor of described step 1 is a computer or other speech signal processing modules, and they form the data array that contains sound overall picture information after the external acoustic signal that collects is banded, transformed, feature extraction processing, and these data can be stored temporarily The computer disk is used for backup, and it can also be directly transmitted by means of communication.

The array data controller in step 2 analyzes the data sequence of the multi-channel structure received by downloading or communication, so that the electrical signals of each channel that change with time are connected to the light source driving circuit corresponding to each channel of the laser fiber array, and control the driving of the light source The parameter corresponding to the optical signal in the module.

The optical fiber collimator in the step 5 is connected to the end of the output optical fiber, and an aspheric lens with an anti-reflection coating is installed inside; the distance between the aspheric lens and the output optical fiber interface can be adjusted to compensate for focal length changes , to collimate the beam of a certain set wavelength at a set distance, and realize the focusing and collimation of the laser beam irradiation.

The specific implementation method of the laser modulation drive unit in the step 3 is: corresponding to the various acoustic signals generated by the FPGA array data controller, the amplitude signal controls the drive current of the controllable constant current source, and the timing control unit controls the high-speed switching circuit. On and off, the joint control of the two generates any current pulse sequence with variable amplitude, adjustable pulse width and pulse repetition rate. The current pulse sequence drives and controls the LD laser to emit a corresponding optical pulse carrying the characteristics of the input acoustic signal.

The beneficial effects of the present invention are:

Using the device of the invention to improve the artificial auditory technology will obtain richer and more comprehensive acoustic information in auditory perception.

The present invention is designed according to the working principle of the existing cochlear implants. Since the front-end nerve arrays of the acoustic information transmission of the animal auditory system are distributed in the cochlea part of the inner ear, these nerve arrays have a corresponding relationship with the audio frequency components that animals can sense. A new information transmission method is proposed for the rough transmission of audio frequency information and the limited transmission mode of the existing cochlear implants. Compared with the existing polyconductive metal electrode cochlear implant, the invention can produce finer transmission in sound frequency resolution, and can implement a finer and more accurate nerve bundle excitation mode in terms of the time relationship of array signals. Here is a general comparison of the sensory characteristics of the human cochlea. The main sensory segment of the human cochlear basilar membrane is about 2 cm long, and the cochlear apex or cochlear tip is the low-frequency end, as shown in Figure 4, corresponding to the most commonly perceived sound frequency band of 5000 Hz. At present, the general number of electrodes of multi-conductor cochlear implants is more than ten to twenty conductors. Taking 22 conductors as an example, the average frequency resolution is about 5000/22=227Hz (of course, in the sensory audio range of 20Hz-5000Hz, human The ear perception frequency relationship is not uniform or linear, but corresponds to the relationship on a logarithmic scale), so that the average distance between the electrodes of each channel is about 1mm; if optical fiber conduction is used, since the optical fiber is very thin, fine nerve fibers can be connected Beams, and adjacent fiber signals will not interfere with each other, can be densely distributed and excited in parallel, so not only the number of channels can be greatly increased, but the excitation mode can also be acoustically transmitted according to the actual situation. Taking the 50um caliber fiber as an example, the fiber array can reach 2cm/50um=400 multiguides, and its spectral resolution can reach 5000/400=12.5Hz on average; if a thinner fiber (such as 10um) is used, the spectrum can also be doubled resolution. It can be seen that this invention has far-reaching significance for the improvement of cochlear implants in the future. Richer, more detailed and realistic sound information transmission will bring more "gospel" to CI implanters, and enjoying music will no longer be difficult. Unpleasant things, its quality of life will be greatly improved.

Description of drawings

Fig. 1 Structure block diagram of photoacoustic array signal generation system;

Fig. 2 Structural block diagram of laser modulation drive unit;

Fig. 3 flow chart of optical pulse signal generation;

Fig. 4 The frequency distribution diagram of human cochlear auditory nerve induction sound.

In the figure: 1 voice processor, 2 array data controller, 3 laser modulation driver, 4 laser fiber array, 5 fiber collimator; 6 channels, 7 optical pulses, 8 optical fibers, 9AC-DC conversion device, 10LD controllable constant Current drive unit, 11 pulse timing control unit, 12 MOSFET high-speed switching circuit, 13LD laser, 14 power supply unit, 15 electrical control unit.

detailed description

The utility model is described in detail below in conjunction with accompanying drawing:

As a necessary device for array fiber laser to induce hearing, a signal device that can generate array fiber laser signals and then excite animal auditory front ganglion bundles (or arrays) is needed to induce the auditory response corresponding to the auditory functional area of the brain. The utility model proposes a laser-induced auditory light signal generating device that drives an array light source with multiple electrical signals to generate an array fiber optical pulse 7 signal, and then stimulates the emission of auditory nerves.

The array optical signal generation system used to stimulate the auditory nerve bundle consists of five parts, as shown in Figure 1, including a speech processor 1, an array data controller 2, a laser modulation driver 3 (including a power supply unit 14, an LD controllable Constant current drive unit 10 , pulse timing control unit 11 , MOSFET high-speed switch circuit 12 , LD laser 13 , electrical control unit 15 ), laser fiber array 4 , fiber collimator 5 . The laser modulation driver 3 is responsible for converting the multiple electrical signals output by the speech processor 1 into corresponding optical signals. The voice processor 1 is connected to the array data controller 2, and the array data controller 2 controls each electrical signal respectively, and is connected to the corresponding laser modulation driver 3 through each channel 6, and each laser modulation driver 3 is connected to the laser fiber array 4 The laser fiber array 4 is connected to the corresponding optical fiber collimator 5 through the optical fiber 8, and finally each optical signal output irradiates the corresponding position of the auditory nerve of the living body. The optical signal output of each port of the laser fiber array 4 corresponds to the audio frequency band divided by logarithmic scale (also called Mel scale), that is, each optical fiber signal output corresponds to a corresponding audio frequency band signal.

The conversion process of multi-channel electrical signal driving array fiber optical signal includes the following steps:

Step 1 Speech processor 1 transforms, band-segments, and extracts features from the collected broadband sound signal to form an array electrical signal with an acoustic information structure. The frequency bands of each channel signal conform to the auditory characteristics of the human ear. The electrical signals of the channels respectively correspond to one optical signal in the laser fiber array.

Step 2: The array data controller 2 converts the electrical signals of the acoustic information structure into electrical signals for driving the LD laser 13 in each single channel. repetition rate etc.

Step 3 In each laser modulation driver part, according to the time when the electrical signal appears, the size of the amplitude and the position of the frequency band, the timing, strength and duration (ie pulse width) of the control optical pulse 7 can be adjusted and controlled, and the constant current drive can be controlled The unit controls the intensity of the optical pulse 7, and the MOSFET high-speed switching circuit 12 is responsible for converting the continuous light emitted by the LD laser 13 into pulsed light corresponding to the electrical signal of the channel, thereby modulating the sound information carried by the electrical signal of each channel to each channel of the optical fiber array. On the optical signals corresponding to the channels, these optical signals still maintain the audio information of the logarithmic scale frequency interval.

Step 4. The optical signals of each channel are output by the optical fiber array, and the signals of each channel can be transmitted synchronously, with mutual independence and stability, and no cross interference.

Step 5: At the corresponding irradiation position, focus the output laser beam through the fiber collimator.

The speech processor 1 of described step 1 can be a computer or other special-purpose speech signal processing modules, and the external sound signal that gathers is through subbanding, transforming, coding, forms the data array that contains sound overall picture information, and these data both can temporarily store computer The disk is reserved, and it can also be directly transmitted by communication.

The array data controller 2 in the step 2 analyzes the data sequence of the multi-channel structure received by downloading or communication, so that the electrical signals of each channel that change with time are connected to the light source driving circuit of each corresponding laser fiber array, and the light source is controlled. The parameter corresponding to the optical signal in the drive module.

The laser modulation driver 3 in step 3 includes a multi-channel laser control drive unit, which is a module circuit that converts multiple channels of electrical signal data streams into multiple channels of optical signal data streams. The number of laser drive control units is the same as the number of fibers in the fiber array, and the parameters of each laser can be controlled independently and in parallel.

As shown in Figure 2, each laser drive control unit includes the following parts: power supply unit 14, LD controllable constant current drive unit 10, pulse timing control unit 11, MOSFET high-speed switch circuit 12, LD laser 13, electrical control unit 15.

(1) Power supply unit 14 : convert 220V AC mains power into DC power suitable for LD controllable constant current drive unit 10 through AC-DC conversion device 9 , and the power supply unit is connected with LD controllable constant current drive unit 10 .

(2) LD controllable constant current drive unit 10: Under the power supply of DC voltage (such as 12V), it adopts synchronous step-down high-current drive, and provides the required power for LD laser 13 through the current amplification circuit composed of Darlington tubes. Electric current drives the laser to emit light. At the same time, by controlling the magnitude of the driving current, the driving current is kept constant, and the current changes according to the amplitude of each signal output by the previous array data controller 2 .

(3) Pulse timing control unit 11 : control and generate corresponding pulse sequence signals with controllable pulse repetition frequency and pulse width according to the timing relationship of channel electrical signals.

(4) MOSFET high-speed switching circuit 12: connected with LD laser 13, taking the driving current generated by the LD controllable constant current source driving circuit as input, and cooperating with the timing signal generated by the timing control unit, so that the MOSFET field effect tube can be quickly switched on and off , to control the excitation current signal output to the LD laser.

(5) LD laser 13: As a light source for generating optical signals, the wavelength of the light source here is optional. For example, we tried 980nm and 808nm semiconductor lasers with this method.

The optical fiber collimator 5 in the step 5 is connected to the end of the output optical fiber 8, and an aspheric lens with an anti-reflection coating layer is installed inside. The distance between the aspherical lens and the interface of the output fiber 8 is adjustable, which can compensate the focal length change, collimate the light beam with a certain set wavelength at the set distance, and realize the focusing and collimation of the laser beam irradiation.

The specific implementation method of the step 3 to the laser driver module circuit is: corresponding to the various acoustic signals generated by the FPGA array data controller 2, the amplitude signal controls the driving current of the controllable constant current source, and the timing control unit controls the high-speed switching circuit The combined control of the two generates any current pulse sequence with variable amplitude, adjustable pulse width and pulse repetition rate. The current pulse sequence drives and controls the LD laser to emit a corresponding optical pulse 7 carrying the characteristics of the input acoustic signal.

Fig. 3 is a further description of how the electrical signals are converted into optical pulses 7 in the two parts of the "array data controller 2" and "laser modulation driver 3" in the "system block diagram" of Fig. 1. It is a signal processing flow for each A small piece of audio data needs to be processed through a signal conversion process as shown in Figure 3. Among them, FIFO (First input, first output, meaning "first in first out") is a buffer for storing data during data processing, and the data in this data area comes from voice processor 1.

The electrical signal conversion process of the array data controller 2 and the laser modulation driver 3 is as follows: at the beginning, judge whether the data in the buffer zone is empty, if not, then get the multi-channel data, if so, then return, each passing channel passes the duty cycle After modulation and laser modulation, it is sent to the pulse fiber.

Claims (7)

1. the laser induced hearing device of array fibre, is characterized in that: comprise speech processor, array data controller, Laser Modulation driver, laser fiber array, optical fiber collimator;

Described speech processor, is sent to array data controller after acoustical signal being converted to the signal of telecommunication;

Described array data controller, controls each road signal of telecommunication respectively and is connected with corresponding Laser Modulation driver;

Described Laser Modulation driver, is responsible for the multi-channel electric signal that speech processor exports to be converted to corresponding optical signal; The wherein corresponding road optical signal of a road signal of telecommunication;

Described laser fiber array, is sent to optical fiber collimator by each road optical signal; And the corresponding optical fiber collimator of a road optical signal;

Described optical fiber collimator, focuses on Output of laser light beam by every road optical signal;

Described Laser Modulation driver, comprise multi-path laser modulation driver element, the number of described Laser Modulation driver element is identical with the number of fibers in fiber array, can control the parameter of each road laser instrument independent parallel;

Described multi-path laser modulation driver element, every road Laser Modulation driver element comprises power supply unit, LD controllable constant-current driver element, timing control unit, MOSFET high-speed switching circuit, LD laser instrument;

Described power supply unit, 220V electric main is transformed to the unidirectional current needed for applicable LD controllable constant-current driver element by AC-DC converter, power supply unit is connected with LD controllable constant-current driver element;

Described LD controllable constant-current driver element, under DC-voltage supply, adopt synchronous buck type large driven current density, the current amplification circuit consisted of Darlington transistor provides required electric current to LD laser instrument, drive laser is luminous, and drive current follows each road signal amplitude change that prime array data controller exports;

Described timing control unit, controls to produce the pulse sequence signal accordingly with controllable pulse repetition rate and pulsewidth according to the sequential relationship of the passage signal of telecommunication;

Described MOSFET high-speed switching circuit, be connected with LD laser instrument, the drive current produced with LD controllable constant-current source driver element is input, and the clock signal that timing control unit produces matches, make MOSFET field effect transistor quick on-off, control the excitation current signal outputting to LD laser instrument;

Described LD laser instrument, as the light source producing optical signal, its optical source wavelength can be selected.

2. laser induced hearing device as claimed in claim 1, it is characterized in that: the optical signal of each port of described laser fiber array exports corresponding with the tonal range that logarithmic scale divides respectively, Ji Mei road fiber-optic signal exports a corresponding corresponding tonal range signal.

3. a signal conversion method for the laser induced hearing device of array fibre, is characterized in that, comprise the steps:

The broadband acoustical signal of collection carries out converting by step 1 speech processor, point band, after feature extraction process, form the array electric signal with acoustic intelligence structure, each passage signal of telecommunication frequency range will meet human hearing characteristic, divide by logarithmic scale, the signal of telecommunication of each passage is corresponding with laser fiber array Zhong mono-road optical signal respectively;

The signal of telecommunication of acoustic intelligence structure is converted to the signal of telecommunication that each single channel drives LD light source by step 2 array data controller, and these signals of telecommunication are corresponding with the controling parameter of driving light source;

The time that step 3 every road Laser Modulation driver element occurs according to the signal of telecommunication, the size of amplitude and frequency range position, the moment that regulable control light pulse occurs, power and persistent period, LD controllable constant-current driver element controls the intensity of light pulse, wherein MOSFET high-speed switching circuit is responsible for converting the continuous light that LD laser instrument sends to the pulsed light corresponding with the passage signal of telecommunication, thus the acoustic information entrained by each passage signal of telecommunication is modulated on optical signal corresponding to each road of fiber array, these optical signals still remain the audio-frequency information of logarithmic scale frequency interval;

Step 4 each road optical signals fiber array exports, and the optical signal synchronous driving of each road, has mutual independence and stability each other;

Step 5, at corresponding irradiation position, focuses on Output of laser light beam by optical fiber collimator.

4. signal conversion method as claimed in claim 3, it is characterized in that: the speech processor of described step 1 is computer or other voice signal processing module, they by the extraneous acoustical signal gathered through a point band, convert, after feature extraction process, form the data array comprising sound overall picture information, it is for subsequent use that these data can keep in computer disk, also directly transmits by communication modes.

5. signal conversion method as claimed in claim 3, it is characterized in that: the array data controller of described step 2 will to be downloaded or the data sequence of multichannel structure that communication receives is resolved, the light source driving circuit of the time dependent signal of telecommunication in Shi Ge road laser fiber array corresponding to each road docks, and controls the parameter of corresponding optical signal in light source driver module.

6. signal conversion method as claimed in claim 3, it is characterized in that: the optical fiber collimator in described step 5 is connected to the end of output optical fibre, the non-spherical lens of anti-reflective film layer is equipped with in inside; Distance between described non-spherical lens and output optical fibre interface can be adjusted, and can compensate focal length variations, collimates the light beam of a certain setting wavelength under setpoint distance, realizes the focusing to laser beam irradiation and collimation.

7. signal conversion method as claimed in claim 3, it is characterized in that: the driving implementation method of the Laser Modulation driver element of described step 3 is: each road acoustical signal that corresponding FPGA recording controller produces, range signal wherein controls the drive current in controllable constant-current source, timing control unit controls the break-make of high-speed switching circuit, the two jointly controls the adjustable any current pulse sequence of generation variable-magnitude, pulsewidth and pulse recurrence rate, this current pulse sequence drived control LD laser instrument, sends the light pulse of carrying input acoustical signal characteristic accordingly.