JP4423398B2 - External sound perception device - Google Patents

Description

  The present invention relates to an external sound perception apparatus for perceiving external sound by ultrasonic vibration.

  Hearing aids for the hearing impaired are known as external sound perception devices for perceiving external sounds such as voice (language sounds) and environmental sounds. Hearing aids include air-conducting hearing aids that transmit sound vibrations through the eardrum to the auditory organ of the brain, and bone-conducting hearing aids that transmit sound vibrations directly from the skull to the human body without passing through the eardrum. Yes, the vibrator is used by attaching it to a predetermined part of the human body.

Recently, a configuration is known in which external sound can be perceived by transmitting ultrasonic vibration to an auditory organ of the brain via an ultrasonic transducer. For example, Patent Document 1 discloses an external sound perception device configured to transmit ultrasonic signals from a plurality of ultrasonic transducers based on external sound input to a microphone.
JP 2004-343302 A

  However, in the transmission of external sound by the ultrasonic vibrator, the frequency characteristics of the output vibration may be distorted due to the fact that it has a resonance frequency in the frequency band presented by the ultrasonic vibrator. There is room for further improvement in clearly transmitting acoustic information over a wide frequency band such as sound.

  Further, the frequency characteristics of the ultrasonic transducer are not only different depending on individual differences, but also change depending on the pressing force when the ultrasonic vibrator is brought into close contact with the human body. For example, when comparing the frequency-impedance characteristics due to the sweep wave between the state where the ultrasonic transducer is unloaded and the state where the ultrasonic body is pressed against the human body (milky protrusion) with a pressing force of 5.1 N, As shown in FIG. 10 (a), the resonance frequency is about 40 kHz, whereas in the latter case, the resonance frequency is greatly reduced to about 30 kHz as shown in FIG. 10 (b). Thus, in order to improve the above-described distortion of the frequency characteristics, it is necessary to consider the characteristics and attachment state of each ultrasonic transducer.

  Therefore, an object of the present invention is to provide an external sound perception device that can clearly perceive external sound regardless of the characteristics and use state of an ultrasonic transducer.

The object of the present invention is an external sound perception device for perceiving external sound by ultrasonic vibration, by modulating a carrier signal based on a microphone to which the external sound is input and the input sound signal. A vibration signal generating unit having a smoothing filter unit that generates a vibration signal and applies a smoothing filtering process to the vibration signal; a filter generation unit that sets a filter coefficient of the smoothing filter unit;
A vibrator that transmits ultrasonic vibration to a living body based on the vibration signal that has passed through the smoothing filter unit, and the filter generation unit includes a sine wave signal generation unit that outputs a frequency-swept sine wave signal; Applying a frequency swept sine wave signal to the vibrator to measure the frequency characteristics of the impedance between the terminals of the vibrator, and the filter coefficient of the smoothing filter section based on the measured impedance characteristics This is achieved by an external sound perception device including an arithmetic processing unit to be set.

In the external sound perception apparatus, a plurality of microphones and vibrators are provided in association with each other, and ultrasonic vibrations are transmitted from the corresponding vibrators based on external sounds input to the microphones. The vibration signal generating means can perform a specific modulation for each external sound input from each directional microphone, and the smoothing filter section is provided to each microphone. Preferably, a plurality of filters are provided, and the filter generation unit individually sets the filter coefficients of the respective smoothing filter units.

  ADVANTAGE OF THE INVENTION According to this invention, the external sound perception apparatus which can perceive an external sound clearly irrespective of the characteristic and use condition of an ultrasonic transducer | vibrator can be provided.

  Hereinafter, actual forms of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view showing a schematic configuration of an external sound perception apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram thereof. As shown in FIGS. 1 and 2, the external sound perception apparatus includes a plurality of directional microphones 10 and 10 to which external sound is input, and a vibration signal generation unit that generates a vibration signal based on the input sound signal. 20 and a plurality of vibration transmission units 30 and 30 for transmitting mechanical vibration based on the vibration signal.

  The plurality of directional microphones 10 and 10 are respectively attached to a casing 20a in which the vibration signal generation unit 20 is accommodated. The directional microphones 10 and 10 are fixed so that the main axis directions of the directivities are different in the present embodiment, but the main axis directions may be attached so as to be adjustable. The external sound input to each of the directional microphones 10 and 10 is input to the vibration signal generation unit 20 after being amplified.

  The vibration signal generation unit 20 generates carrier signals based on carrier signal generation instructions, carrier signal generation instructions 22, carrier signal generation instructions, carrier signal frequency, amplitude, timing (phase), and modulation method. Are generated, and carrier signal modulation units 26 and 26 that generate a vibration signal by modulating a carrier signal based on a sound signal input from the directional microphones 10 and 10 are generated. Smoothing filter sections 28 and 28 for performing a smoothing filtering process on the vibration signal are provided, and the vibration signal is generated individually for each input sound of the directional microphones 10 and 10.

  The input unit 24 includes a volume switch 24a that can be individually adjusted so that the frequency, amplitude, and phase of the carrier signal can be continuously changed, and further, a dial switch 24b for selecting a modulation method. It has. Examples of selectable modulation methods include frequency modulation, amplitude modulation, phase modulation, and the like, and examples of amplitude modulation include double sideband (DSB), single sideband (suppressed carrier wave) (SSB), and the like. Can be selected. The input unit 24 includes a carrier signal generation switch 24c for instructing the generation of the carrier signal by the set frequency, amplitude, and phase of the carrier signal.

  The frequency of the carrier signal is preferably from 20 to 100 kHz, more preferably from 20 to 50 kHz, so as to obtain a good sound sensing state even for a highly deaf person. Therefore, it is preferable that the input unit 24 can adjust the frequency of the carrier signal in a range including a part or all of the frequency range.

The smoothing filter unit 28 smoothes the frequency characteristic of the vibration signal generated by the carrier signal modulation unit 26 in the frequency band to be presented. A plurality of smoothing filter units 28 are provided corresponding to each directional microphone 10, and filter coefficients are set individually for each.

  The vibration transmitting unit 30 includes vibrators that transmit vibration signals to the outside as mechanical vibrations, and each vibrator is associated with a plurality of directional microphones 10 and 10, respectively. The external sound input to 10 is transmitted from the corresponding transducer.

  As shown in FIG. 3, each vibration transmission unit 30 includes a cylindrical case 32 in which a vibrator 31 is accommodated, and a suction cup 34 is attached to the opening edge of the case 32.

  The vibrator 31 is supported by a gimbal mechanism so as to be swingable about two axes orthogonal to each other. That is, the vibrator 31 is fixed to the first frame body 40 so that the vibration surface is exposed, and the first frame body 40 is attached to the second frame body 44 via the first support shaft 42. It is swingably supported. The second frame body 44 is swingably supported inside the case 32 via a second support shaft 46 orthogonal to the first support shaft 42. The vibration surface of the vibrator 31 protrudes slightly from the opening of the case 32. When the suction cup 34 is attracted to a predetermined attachment site, the vibration surface of the vibrator 31 is in contact with and pressed against the attracted surface. Has been. A communication hole 32a is formed at the center of the bottom (upper part of the figure) of each case 32, and a spherical bag-like body 48 is coupled to the communication hole 32a. The bag-like body 48 is made of an elastic material such as a rubber material, and is configured to be elastically deformable by pressing. The internal space of the bag-like body 48 communicates with the inside of the case 32 through the communication hole 32a.

  In addition, the external sound perception apparatus of the present embodiment includes a filter generation unit 50 for setting the filter coefficient in the smoothing filter unit 28. As shown in FIG. 4, the filter generation unit 50 outputs a sine wave signal that is frequency-swept, and a sine wave signal generation unit 52 that outputs the frequency-swept sine wave signal. An impedance measuring unit 54 that measures the frequency characteristics of the impedance between the terminals, and an arithmetic processing unit 56 that sets the filter coefficient of the smoothing filter unit 28 based on the measured impedance characteristics are provided. As shown in FIG. 1, the input unit 24 includes a sine wave signal generation switch 24d for instructing generation of a frequency swept sine wave signal, and an output from the sine wave signal generation unit 52 is a sine wave signal generation. This is performed based on an input from the input unit 24 by operating the switch 24d.

The frequency sweep width of the sine wave signal output from the sine wave signal generation unit 52 may be set in consideration of the frequency of the carrier signal for generating the vibration signal, and is, for example, 20 to 100 kHz. The arithmetic processing unit 56 estimates the filter coefficient of the inverse filter based on the measured frequency characteristic of the impedance. Specifically, the frequencies corresponding to the maximum and minimum of the frequency characteristics of the measured impedance are obtained as the antiresonance frequency and the resonance frequency, respectively. From the antiresonance and resonance frequency, the poles and zeros of the inverse filter in the polar coordinate system are deviated. Set the angle (θp, θz). Then, a temporary inverse filter is created using the radius (rp, rz) and gain k of the poles and zeros as parameters, and the optimum value of the inverse filter is searched by repeating measurement and smoothness evaluation. Search methods can include optimization methods such as linear programming and genetic algorithms. Thus, the pole, zero, and gain can be converted into a filter coefficient matrix, and the filter coefficient of the smoothing filter unit 28 can be set.

In the present embodiment, the impedance measurement unit 54 measures the frequency characteristics of the impedance of the vibrator 31, and the arithmetic processing unit 56 sets the filter coefficient of the smoothing filter unit 28 based on the measurement result. However, instead of the impedance measuring unit 54, a vibration measuring unit such as a laser Doppler vibrometer is provided. In this vibration measuring unit, the frequency characteristic of vibration on the vibration surface of the vibrator 31 is measured, and a smoothing filter unit is obtained from the measured data. 28
It is also possible to set the filter coefficient.

  Next, the operation of the external sound perception apparatus will be described. First, the plurality of vibration transmission units 30 and 30 are respectively attached to predetermined parts of the human body (for example, in the vicinity of the left and right milky protrusions). Each vibrator 31 can be reliably brought into contact with the human body by the gimbal mechanism by pressing the suction cup 34 against a predetermined portion while the bag-like body 48 is picked by hand. Thereafter, when the hand that has been picked is released, the inside of the case 32 becomes a negative pressure due to the shape restoring force of the bag-like body 48 and an adsorption force is obtained, so the attachment of the vibrator 31 can be ensured.

  Thereafter, when the user turns on the sine wave signal generation switch 24d, each filter generation unit 50 outputs a sine wave signal swept in frequency from the sine wave signal generation unit 52, and the filter coefficient of the smoothing filter unit 28 Is set. When the filter coefficient of each smoothing filter unit 28 is set, the completion of setting is notified by a buzzer sound, a confirmation lamp or the like, and the sine wave signal generation switch 24d is automatically turned off, and the sine wave signal generation unit The output of the sine wave signal at 52 is stopped. As described above, the smoothing filter unit 28 individually sets the filter coefficients, reflecting the characteristics and attachment states of the corresponding transducers 31.

  Next, when the user turns on the carrier signal generation switch 24c and external sound is input to the directional microphones 10 and 10, sound signals are input from the directional microphones 10 and 10 to the vibration signal generation unit 20. . Since the directional microphones 10 and 10 have different directivity main axis directions, input sensitivities to the same sound source are different. FIG. 5 shows an example of a time waveform of an audio signal input to the directional microphone 10 and corresponds to the audio “KEISATSU”.

  In the vibration signal generation unit 20, the carrier signal generation units 22 and 22 generate a carrier signal having a predetermined amplitude and frequency, and the carrier signal modulation units 26 and 26 modulate the carrier signal based on the sound signal. Thus, a vibration signal corresponding to the input sound to each directional microphone 10, 10 is generated. At this time, different modulation conditions are input via the input unit 24 so that the carrier signal modulation units 26 and 26 perform unique modulation for each input sound to the directional microphones 10 and 10, respectively. . For example, the carrier signal frequency is set to be different for each of the directional microphones 10, 10, and the modulation method is the same double sideband amplitude modulation, and each modulation can be performed. Alternatively, the carrier signals may have the same frequency, and the modulation methods may be different from each other (for example, one is a double sideband amplitude modulation and the other is a suppressed carrier wave amplitude modulation), and each may be subjected to a specific modulation. FIG. 6 shows a time waveform of a modulated signal obtained by performing double-sideband amplitude modulation with the audio signal shown in FIG. 5 using a 30 kHz sine wave as a carrier signal in the carrier signal modulator 26.

  The vibration signal generated in this way is subjected to smoothing processing in the smoothing filter unit 28 and then output to the corresponding vibration transmission units 30 and 30. The vibration transmitting units 30 and 30 vibrate the vibrators 31 and 31 based on the input vibration signal. As a result, ultrasonic vibrations are transmitted from the corresponding vibration transmitting units 30 and 30 to the human body based on the external sound input to the directional microphones 10 and 10, respectively. The carrier signal modulation unit 26 performs control so as not to output a vibration signal during a period in which no sound signal is input.

  In actual use, it is assumed that the attachment state of the ultrasonic transducer is different at each mounting or changes due to a shift during use. When the attachment state of the ultrasonic transducer changes, the sine wave signal generation switch 24d is turned on again to output a sine wave signal, and the filter coefficient of the smoothing filter unit 28 can be set again.

According to the external sound perception apparatus of the present embodiment, the vibration signal generated based on the input of the external sound is configured to be transmitted from the vibration transmission unit 30 after being filtered by the smoothing filter unit 28. Therefore, it is possible to smooth the frequency characteristics of the transmitted ultrasonic vibration in the frequency band to be presented. As a result, distortion of external sounds such as voice and environmental sounds can be suppressed, and the user can clearly perceive the external sounds.

  FIG. 7A shows a time waveform of the output signal from the vibration transmitting unit 30 when the smoothing process is performed on the modulated signal shown in FIG. When this output signal is compared with the output signal when the smoothing process shown in FIG. 7B is not performed, it can be seen that the waveform disturbance is suppressed by the smoothing process.

  FIGS. 8A and 8B show the time waveform of a signal obtained by demodulating the output signal shown in FIGS. 7A and 7B, respectively, with the time waveform of the audio signal shown in FIG. . When the smoothing process is performed, as shown in FIG. 8A, the time waveform of the demodulated signal is substantially the same as the time waveform of the audio signal, whereas when the smoothing process is not performed, As shown in FIG. 8B, the waveform of the demodulated signal is greatly broken particularly in the consonant part. FIGS. 9A and 9B show spectral waveforms corresponding to FIGS. 8A and 8B, respectively, and the difference between the spectrum of the demodulated signal and the audio signal, particularly at high frequencies, is obtained by smoothing processing. Is suppressed. Thus, it can be seen that by performing the smoothing filtering process in the smoothing filter unit 28, the voice information is clearly transmitted in a wide frequency band.

  In addition, the external sound perception apparatus of the present embodiment is configured so that the vibration signal generation unit 20 can perform modulation specific to each external sound input from each directional microphone 10, 10. Each modulation condition is set in advance so as to recognize the difference in “hearing (timbre)” of the ultrasonic vibration transmitted from each vibration transmitting unit 30, 30, and the directional microphones 10, 10 corresponding to each “hearing” are set. , The user can determine from which directional microphone 10 the perceived ultrasonic signal is input. For example, if the modulation method is double-sideband amplitude modulation, both the carrier wave pitch and the demodulated signal wave pitch are perceived simultaneously, while if the modulation method is suppressed carrier amplitude modulation, the carrier wave Is not perceived, and only a pitch corresponding to twice the frequency of the original signal wave is perceived, so that the difference in “hearing” can be reliably determined. In particular, in the present embodiment, since the ultrasonic vibrations transmitted from the vibration transmission units 30 and 30 are subjected to smoothing processing in the smoothing filter units 28 and 28 generated individually, Variations in frequency characteristics due to individual differences of the transducers 31 and pressing force at the time of attachment can be suppressed, and sound source localization can be performed satisfactorily. As a result, it becomes possible for the user to surely recognize the direction of the sound source such as voice or environmental sound, which is effective, for example, when working at a disaster site or construction site, or when driving a vehicle such as an automobile.

  In the present embodiment, the above-described configuration of the vibration transmitting unit 30 can effectively prevent positional displacement of the transducer 31 over time, but the sound pressure distribution in the head is determined by the mounting position of each transducer 31. Therefore, it is difficult to accurately attach each vibrator 31 to a portion where the sound sensing state is optimal. Therefore, after attaching each transducer 31, the frequency, phase, amplitude, etc. of the carrier signal corresponding to each transducer 31 are adjusted by operating the input unit 24, and the positions of the abdomen and nodes caused by ultrasonic interference are controlled. It is preferable to optimize the sound sensing state by reducing the focal point of the ultrasonic wave and locally increasing the sound pressure. When the modulation condition is set so that the frequency of the carrier signal is different for each directional microphone 10, 10, the carrier signal is adjusted in the adjustment of the sound sensing state so that the sense of direction of the perceived sound is not lost. The frequency is preferably not changed.

Although the specific method for optimizing a sound-sensitive state is not specifically limited, For example, the following method can be mentioned. First, the amplitude of the ultrasonic waves emitted from the plurality of vibrators 31 is set to be small, and each of the vibrators 31 is appropriately attached to each mastoid so that the sound-sensing state is generally good. Perform positioning. Then, the frequency and phase of each transducer 31 are adjusted and determined so that the sound sensing state becomes better. For example, when two vibrators 31 are attached and used, the frequency of the carrier signal corresponding to each vibrator 31 is simultaneously changed to set the frequency at which the sound sensing state is the best. Thereafter, by setting the phase of the carrier signal corresponding to each vibrator 31 in the same manner, the optimum frequency and phase of the carrier signal can be obtained individually for each vibrator 31, and the sound sensing state Can be optimized. Either the frequency or phase may be set first. Finally, the amplitude is set to a desired magnitude so that a desired sound sensing state can be obtained.

  As another method for optimizing the sound sensing state, the carrier signal corresponding to the other transducer 31 while maintaining the frequency, phase and amplitude of the carrier signal corresponding to one transducer 31 at predetermined values. It is also possible to optimize the sound sensing state by sequentially changing the frequency, phase and amplitude. In this case, it is only necessary that the input unit 24 can adjust the frequency, phase, and amplitude of the carrier signal corresponding to at least one transducer 31. In any case, by adjusting the frequency, phase, and amplitude of the carrier signal in a state where the difference in “hearing” can be reliably determined, it is possible to obtain both a good sound feeling state and a sense of direction.

  As mentioned above, although one Embodiment of this invention was explained in full detail, the specific aspect of this invention is not limited to the said embodiment. For example, in the present embodiment, two directional microphones 10 and 10 are used, and each input sound is configured to perform unique modulation. However, the directional microphone and vibration transmission corresponding to the directional microphone are used. The number of parts is not particularly limited. For example, when this external sound perception device is installed in an automobile, four directional microphones are fixed to the vehicle so that the main axes of directivity are forward, backward, right, and left, respectively. The sound may be configured to be transmitted to the human body through four corresponding vibration transmission units after performing a specific modulation on the sound. This makes it possible to reliably grasp the direction of a sound source that needs to be recognized during driving, such as a siren of an emergency vehicle. On the other hand, it is possible to have a configuration in which one microphone and one vibration transmission unit are provided. In this case as well, it is possible to clearly perceive external sound.

  In this embodiment, the modulation condition can be input via the input unit 24. However, by determining a modulation condition suitable for the user in advance and storing the data in a memory or the like. A configuration without the input unit 24 is also possible. Moreover, the input of the change condition from the input unit 24 is not limited to manual operation, and the result of measurement and calculation by another device may be automatically input.

It is a front view which shows schematic structure of the external sound perception apparatus which concerns on one Embodiment of this invention. It is a block diagram of the external sound perception device. It is sectional drawing of the vibration transmission part in the said external sound perception apparatus. It is a block diagram of the filter production | generation part in the said external sound perception apparatus. It is a figure which shows an example of the time waveform of the audio | voice signal input into the said external sound perception apparatus. It is a figure which shows an example of the time waveform of the modulation signal produced | generated with the said external sound perception apparatus. It is a figure which shows an example of the time waveform of the output signal from the said external sound perception apparatus, (a) shows the case where smoothing processing is performed, (b) shows the case where smoothing processing is not performed. It is a figure which shows an example of the time waveform of the signal which demodulated the output signal from the said external sound perception apparatus, (a) shows the case where smoothing processing is performed, (b) shows the case where smoothing processing is not performed. Yes. It is a figure which shows an example of the spectrum waveform of the signal which demodulated the output signal from the said external sound perception apparatus, (a) shows the case where smoothing processing is performed, (b) shows the case where smoothing processing is not performed. Yes. It is a figure which shows the result of having measured the impedance characteristic by changing the attachment state of a vibrator | oscillator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Directional microphone 20 Vibration signal generation part 22 Carrier signal generation part 24 Input part 26 Carrier signal modulation part 28 Smoothing filter part 30 Vibration transmission part 31 Vibrator 50 Filter generation part 52 Sine wave signal generation part 54 Impedance measurement part 56 Calculation Processing part

Claims (2)

An external sound perception device for perceiving external sound by ultrasonic vibration,
A microphone to which external sound is input;
A vibration signal generating unit having a smoothing filter unit that generates a vibration signal by modulating a carrier signal based on an input sound signal and performs a smoothing filtering process on the vibration signal;
A filter generation unit for setting a filter coefficient of the smoothing filter unit;
A vibrator that transmits ultrasonic vibrations to a living body based on the vibration signal that has passed through the smoothing filter unit;
The filter generation unit measures a frequency characteristic of impedance between terminals of the vibrator by applying a frequency swept sine wave signal to the vibrator and a sine wave signal generator that outputs the frequency-swept sine wave signal. An external sound perception apparatus comprising: an impedance measurement unit that performs a calculation; and an arithmetic processing unit that sets a filter coefficient of the smoothing filter unit based on the measured impedance characteristics . A plurality of microphones and vibrators are provided in association with each other, and ultrasonic vibrations are transmitted from the corresponding vibrators based on external sounds input to the microphones. And
The vibration signal generation means can perform modulation specific to each external sound input from each directional microphone, and a plurality of the smoothing filter units are provided corresponding to the respective microphones.
The external sound perception apparatus according to claim 1, wherein the filter generation unit individually sets a filter coefficient of each of the smoothing filter units.