JPH05344595A - Audio signal processor - Google Patents

Abstract

(57) [Abstract] [Purpose] In a high-performance hearing aid having a signal processing circuit, avoid the occurrence of a completely silent state as much as possible, limit wasteful power consumption, prolong battery life, and downsize the device. -Enables weight reduction. [Structure] In a hearing aid in which an input signal of a microphone 1 is amplified by an input amplifier 2 and processed by a signal processing circuit 4, an input amplifier is driven by an output amplifier 6 to reduce an input audio signal level by an audio level determination circuit 3. Even in this case, the three-value determination is performed and the power supply of the signal processing circuit 4 and the output amplifier 6 is controlled. When there is almost no sound, power supply to both the signal processing circuit 4 and the output amplifier 6 is cut off. At the normal sound field level, the signal processing circuit 4 is cut off from the power supply,
The output signal of the input amplifier 2 is selected by the switcher 5,
The output amplifier 6 drives the earphone 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention assists the hearing of a hearing-impaired person.
The present invention relates to a high-performance hearing aid that acts on your behalf.

[0002]

2. Description of the Related Art In hearing aids that are supposed to be carried or worn while being used, reduction of power consumption is an important technology. In particular, recently, a device having a signal processing circuit for performing frequency processing or the like according to the hearing characteristics of an individual has been studied (for example, the ME Society of Japan BME magazine.
Vol. 4, No. 1, issued January 10, 1990), power saving has become an increasingly important issue. Conventionally, as a method for reducing power consumption, a method as disclosed in JP-A-55-4160 is known. This is to detect that the audio signal is below a certain level by a comparator and shut off the power supply to the output amplifier and the speaker or earphone.

[0003]

The above-mentioned prior art attempts to reduce the power consumption by determining whether the input voice level is a certain value or above and below it, and controlling the on / off of the supplied power. Therefore, even in a normal living environment, no consideration has been given to the occurrence of complete silence,
Although it is for saving power, the hearing aid wearer is left in a completely silent environment for a relatively long time, which causes a problem of causing psychological anxiety.

The object of the present invention is to avoid the occurrence of a completely silent state as much as possible even in a high-performance hearing aid having a signal processing circuit and the like, thereby prolonging the life of the battery, and further downsizing the device.
It is to provide a hearing aid that can be made lightweight.

[0005]

In order to achieve the above object, the present invention is provided with two audio level determination circuits, and a switch circuit is provided in a power supply line to a signal processing circuit for performing frequency processing of an audio signal. And a switching circuit for switching between the output signal of the input amplifier for the audio signal and the output signal of the signal processing circuit is provided in the input section of the output amplifier.

A programmable clock generator is used as a clock signal generation source for the signal processing circuit. Also,
A switch circuit that cuts off the power supply is provided in the memory circuit unit that stores the program for controlling the signal processing circuit.

[0007]

The two-system audio level judging circuit can judge the output signal level of the input amplifier, that is, the surrounding sound field level in three stages (window comparator). As a result, a sound field level (45 [dB SPL] or less as a guideline), a normal living sound field level (46 to 55 [dB SPL]), and a level above it, should be recognized even by healthy people. Therefore, it is possible to take power saving measures according to the surrounding conditions.

Further, the switch circuit inserted in the power supply line of the signal processing circuit or the like operates so as to cut off the power source of only the corresponding circuit unit. As a result, it is possible to output living environment noise or simulated living environment noise by utilizing that the system other than the power shutoff unit is operating normally, without giving the wearer the fear of being completely silent. It is possible to save power.

Further, the switching circuit inserted in the input of the output amplifier operates so as to switch and output both the output signal of the signal processing circuit which has been subjected to frequency processing and the like and the input sound source signal. As a result, even in a power-saving state in which the power supply of the signal processing circuit or the like is cut off, it is possible to eliminate the anxiety caused by the completely silent state or avoid the dangerous state.

Further, the programmable clock generator is
Depending on the sound field level determined by the signal processing circuit,
It operates so as to generate a clock signal having a minimum frequency required for signal processing at each sound field level. As a result, the CM consumes power almost linearly with the driving frequency.
Power consumption of the signal processing circuit including the OS circuit can be reduced.

The switch circuit inserted in the power supply line of the program memory can be operated so as to be temporarily turned on when the power is turned on. Thereby,
After the program has been read, the power supply can be cut off and power consumption can be reduced.

[0012]

[Embodiment 1] FIG. 1 is a block diagram of a hearing aid, in which a microphone 1 for converting an audio signal into an electric signal is shown.
An input amplifier 2 for amplifying an electric signal, a voice level judging circuit 3 for judging the magnitude of the amplified signal 3, a signal processing circuit 4 for processing the amplified signal 4, an amplified signal of the input amplifier 2 and a processed signal of the signal processing circuit 4 are selected. Switcher 5, an output amplifier that outputs a selection signal 6, an earphone 7 that converts the output signal into an audio signal, a battery 8 that drives all the circuits described above, a switch 9a that shuts off the power supply to the signal processing circuit 4, an output amplifier 6
It is composed of a switch 9b for cutting off the power supply.

The detailed operation of the circuit will be described below. In this embodiment, a voice signal input by the microphone 1 is converted into an electric signal and amplified by the input amplifier 2,
The amplified signal of the input amplifier 2 is supplied to the audio level determination circuit 3
The configuration is such that a signal processing circuit 4 that performs processing according to the hearing ability and understanding ability of a hearing-impaired person and a switch 5 are input. First, when the audio level determination circuit 3 determines that the amplified signal of the input amplifier 2 is in the silent state or very close to the silent state, the switch 9a shuts off the power supply to the signal processing circuit 4, and the switch 9b switches the power supply to the signal processing circuit 4. The power supply to the output amplifier 6 is also cut off.

Further, when the sound level judging circuit 3 judges that the amplified signal of the input amplifier 2 is about the level of the normal sound field, the switch 9a cuts off the power supply to the signal processing circuit 4, and the output amplifier 6 While the power is being supplied to the earphones 7, the amplified signal of the input amplifier 2 selected by the switch 5 is connected to the output amplifier 6 as it is.
To drive. This makes it possible to always perceive the external sound even if the wearer cannot recognize it.

Further, when the voice level judging circuit 3 judges that the amplified signal of the input amplifier 2 is higher than the living sound field level, that is, in the conversation state or at a sound field level equal to or higher than that, the signal by the switch 9a. Power is supplied to the processing circuit 4 and power is supplied to the output amplifier 6 by the switch 9b, the processing signal of the signal processing circuit 4 selected by the switch 5 is connected to the output amplifier 6, and the earphone 7 is driven.

A specific operation of the voice level determination circuit 3 will be described with reference to FIGS. FIG. 2 is a diagram showing an example of a circuit embodying the audio level determination circuit 3. FIG. 3 is a diagram showing waveforms of respective parts of FIG. 2. FIG. 3A is an output signal Va of the input amplifier 2, and FIG. 3B is a plus side input signal Vi and a minus side input of the comparator 3-5. The signals Vr and the upper limit value EH and the lower limit value EL of Vr, and FIG. 7C show the output signal OUT1 of the comparator 3-5, respectively. It should be noted that the audio level determination circuit 3 uses two circuits shown in FIG. 2, but since the only difference in operation is the determination level, only one circuit will be described.

The center tap of the variable resistor 3-10 is connected to the negative input of the comparator 3-5.
The output of the inverter 3-6 is connected to the variable resistor 3-10 via the resistor 3-8, and the output of the inverter 3-7 is connected to the variable resistor 3-10 via the resistor 3-9. At this time, if the resistance value between the center tap of the variable resistor 3-10 and the ground is not zero ohm, the center tap of the variable tap is zero volt regardless of the output signal level (“H” or “L”) of the comparator 3-5. The above potential will be applied. In this embodiment, the variable resistor 3-10 and the resistor 3-
8 and the ratio of the resistors 3-8 and 3-9 are set to appropriate values, and the comparison level Vr has an upper limit value (EH in FIG. 3B) and a lower limit value (EL in FIG. 3B). ) Has a hysteresis characteristic. Thereby, the comparator 3-5
This prevents the output from switching frequently. In the following description, the output signal OUT1 of the comparator 3-5 is "L" level in the initial state. The output signal Va of the input amplifier (2 in FIG. 1) is rectified by the diode 3-1 and
The capacitor 3-3 is charged through the resistor 3-2 and becomes the plus side input signal Vi of the comparator 3-5. here,
When the signal Vi is lower than the potential of the negative side input signal Vr of the comparator 3-5, the output signal OUT1 of the comparator 3-5 remains at "L" level and the output of the inverter 3-6 is at "H" level. The output of the inverter 3-7 is at "L" level. In addition, the signal Va is the capacitor 3
When the signal Vi is charged to −3 and the signal Vi exceeds the upper limit value EH of the signal Vr, the signal OUT1 becomes the “H” level. At the same time, due to the above-mentioned hysteresis characteristic, the signal Vr is lowered to the lower limit value EL, and the signal OUT1 maintains the "H" level. After that, the charge of the capacitor 3-3 changes to the discharge resistance 3-
When the signal Vi becomes lower than the lower limit value EL of the signal Vr, the signal OUT1 becomes the “L” level, and at the same time, the signal Vr returns to the upper limit value EH. Thus, FIG.
If the circuit of 3 is used, the output state of the comparator 3-5 can be switched depending on the level of the input voice.

As described above, according to the first embodiment, by using the two circuits of FIG. 2 and setting the respective signals Vr to appropriate values, the signal processing circuit 4 and the output are set according to the situation of the input voice level. The power supply to the amplifier 6 can be controlled, and the power consumption can be reduced. In addition,
Even when the surrounding sound field level is in the silent state and the power supply to the signal processing circuit 4 and the output amplifier 6 is cut off for a long period of time, the power supply to the output amplifier 6 is intermittently performed, and the simulated living environment is provided. By outputting noise or the like, it is possible to detect in advance a silent state caused by exhaustion of a battery or the like.

<Embodiment 2> FIG. 4 is a block diagram of a hearing aid based on a digital signal processing system according to a second embodiment of the present invention, which has basically the same configuration as that of FIG. 1 showing the first embodiment. To a program memory 11 for storing a signal processing circuit 10 composed of a CMOS circuit, a control program of the signal processing circuit 10 and the like, which is mainly intended to digitally process the output signal of the input amplifier 2, to the program memory 11. And a clock signal generating circuit 13 for generating a clock signal to be supplied to the signal processing circuit 10. The signal processing circuit 10
Also controls the entire hearing aid.

The detailed operation of the circuit will be described below. First, the control program for performing digital signal processing in the signal processing circuit 10 and controlling the entire hearing aid is the program memory 11 when the power is turned on or when necessary (for example, when the reset switch (10-3 in FIG. 5) is pressed).
Is read into the memory of the signal processing circuit 10. At this point, the program memory 11 is no longer needed, and the switch 12 is shut off by the control program.
Cut off the power supply to 1. After that, the frequency of the clock signal generated by the clock signal generation circuit 13 is set to an appropriate value by the control program, and the processing of the audio signal is started.

The specific operation will be performed as follows. The voice signal input by the microphone 1 is converted into an electric signal, amplified by the input amplifier 2, processed by the signal processing circuit 10 according to the hearing characteristics and comprehension of the hearing impaired person, and then amplified by the output amplifier 6. Then, the earphone 7 is driven. Further, the frequency of the clock signal generated by the clock signal generation circuit 13 is the minimum frequency required for the processing depending on the situation of the signal processed by the signal processing circuit 10 or the necessity of the processing. Is managed by the control program.

FIG. 5 shows an embodiment of the signal processing circuit 10. It is composed of an analog interface 10-1 (for example, IC TLC32044 manufactured by Texas Instruments Incorporated), a digital signal processor 10-2, a reset switch 10-3, and an address decoder 10-4. The digital signal processor 10-2 is supplied with the clock signal in the initial state of the clock signal generation circuit (13 in FIG. 4). When the power switch is turned on or the reset switch 10-3 is pressed, the digital signal processor 10-2 reads the control program from the program memory (11 in FIG. 4), and then the address signal is passed through the address decoder 10-4 by the control program. Immediately signal PO
The FF is issued, and the switch (12 in FIG. 4) cuts off the power supply to the program memory.

After that, the signal processing circuit (10 in FIG. 4) starts the following operations according to the control program. The output signal of the input amplifier (2 in FIG. 4) is input to the input terminal IN of the analog interface 10-1 and the AD converter 10-1 via the anti-aliasing filter 10-1a.
Input to b. The AD converter 10-1b sequentially samples the signal and converts it into a digital signal. The digital signal processor 10-2 processes the digital signal according to the control program, and then, the DA converter 10
-1c, and after converting into an analog signal, it outputs to the output amplifier (6 in FIG. 4) from the output terminal OUT via the filter 10-1d. In these series of operations, under the control of the control program, the signal CKSEL is issued through the address decoder 10-4, and the frequency of the clock signal CK generated by the clock signal generation circuit (13 in FIG. 4) is changed. ..

As described above, according to the second embodiment, after the control program is read from the program memory 11 into the memory of the signal processing circuit 10 when the power is turned on or when necessary,
By cutting off the switch 12 and cutting off the power supply to the program memory 11 by the control program, the power consumption can be reduced. Further, since the power consumption of the CMOS circuit is almost linearly proportional to the frequency for driving the circuit, the power consumption can be reduced by changing the frequency of the clock signal CK supplied from the clock signal generation circuit 13 to the signal processing circuit 10. It is possible to reduce.

As described above, the series of circuit configurations from the microphone to the earphone is not limited to one channel and may be two or more channels. Further, although the microphone is used as the means for receiving the voice signal in the embodiment, it is also possible to receive the voice-modulated optical signal by using the photodiode or the like.
Similarly, it was possible to receive a magnetic signal using an induction coil, receive a radio wave using a tuning circuit, and directly receive an electric signal from a television or the like. In addition, good results could be obtained by connecting the microphone of the telephone to the input amplifier and from the output amplifier to the receiver.
Further, the program memory does not have to be built in the apparatus, and a control program may be read by connecting a memory card, a ROM pack, or the like from the outside as appropriate. It is also possible to transfer a control program such as magnetism or radio waves without contact.

[0026]

According to the present invention, since the surrounding sound field level can be determined in at least three levels, it becomes possible to take a power saving measure according to the surrounding conditions, and to reduce the power consumption. An audio signal processing device can be provided.

Further, since the power source of the signal processing circuit can be independently turned off, it becomes possible to control the power consumption, and it is possible to provide an audio signal processing device of low power consumption.

Further, the switching circuit inserted in the input of the output amplifier selects the output signal of the signal processing circuit and the input audio source signal, whereby the external audio signal can be perceived even in the power saving state. It is possible to avoid anxiety and sudden danger due to silence.

Further, it becomes possible to control the power consumption of the signal processing circuit by varying the frequency of the clock signal generating circuit according to the situation of the signal to be processed or according to the necessity of the processing, and it is possible to reduce the power consumption. The audio signal processing device can be provided.

After loading the control program,
It is possible to cut off the power supply to the program memory, and it is possible to provide an audio signal processing device with low power consumption.

[Brief description of drawings]

FIG. 1 is a block diagram of a hearing aid according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an embodiment of audio level determination.

FIG. 3 is a time chart of main signals of a sound level determination circuit.

FIG. 4 is a block diagram of a hearing aid according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram of an example of digital signal processing.

[Explanation of symbols]

1 ... Microphone, 2 ... Input amplifier, 3 ... Audio level determination circuit, 4 ... Signal processing circuit, 5 ... Switching device, 6 ... Output amplifier, 7 ... Earphone, 8 ... Battery, 9a ... Switch.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Nobuo Hamamoto 1-280 Higashi Koikekubo, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. Central research institute

Claims (5)

[Claims] 1. An audio signal comprising an input amplifier for amplifying an audio signal, a signal processing circuit for processing an output signal of the input amplifier, an output amplifier and a speaker or earphone for converting the output signal of the output amplifier into an audio signal. An audio signal processing device, characterized in that in the processing device, the magnitude of an input audio signal is judged in at least three values. 2. An audio signal comprising an input amplifier for amplifying an audio signal, a signal processing circuit for processing an output signal of the input amplifier, an output amplifier and a speaker or earphone for converting the output signal of the output amplifier into an audio signal. In the processing device, the audio signal processing device is characterized in that the power supply to the signal processing circuit is independently cut off. 3. An audio signal comprising an input amplifier for amplifying an audio signal, a signal processing circuit for processing an output signal of the input amplifier, an output amplifier and a speaker or earphone for converting the output signal of the output amplifier into an audio signal. In the processing device, an output signal of the input amplifier is output without passing through the signal processing circuit, and an audio signal processing device. 4. An input amplifier for amplifying an audio signal, a digital signal processing circuit for processing an output signal of the input amplifier, an output amplifier, and a speaker or an earphone for converting an output signal of the output amplifier into an audio signal. In the audio signal processing device, the audio signal processing device is characterized in that the frequency of a clock signal supplied to the signal processing circuit is variable. 5. An input amplifier for amplifying an audio signal, a digital signal processing circuit for processing an output signal of the input amplifier, an output amplifier, and a speaker or an earphone for converting an output signal of the output amplifier into an audio signal. In the audio signal processing device, the power supply to the program memory for the signal processing circuit is cut off.