JP2023173365A - Speaker device and speaker system - Google Patents

Abstract

To provide a speaker device and speaker system capable of suppressing howling in using an electronic stethoscope.SOLUTION: A speaker device includes: a reception section for receiving a signal which expresses auscultatory sound from an electronic stethoscope; a correction section for correcting the signal received by the reception section to suppress a signal level when the signal level is equal to or less than a predetermined value; and an output section for outputting the auscultatory sound expressed by the corrected signal.SELECTED DRAWING: Figure 3

Description

The present invention relates to a speaker device and a speaker system.

2. Description of the Related Art Conventionally, electronic stethoscopes have been known that can use an equalizer to separate only heart sounds and breathing sounds (Patent Document 1).

Japanese Patent Application Publication No. 2005-052521

In the prior art, electronic stethoscopes are characterized by converting patient's auscultation sounds into digital data and transmitting digital wirelessly to perform diagnosis at a location away from the patient. In addition, it is attracting attention as a next-generation stethoscope because data analysis of the auscultation sounds can be easily performed on the receiving terminal side.

Here, it is conceivable to use a monitor speaker using an electronic stethoscope so that multiple people can listen to the auscultation sounds converted into data with the electronic stethoscope. When auscultation sounds are played back by a monitor speaker, the sound output from the speakers is fed back to the chest piece, causing howling, making it difficult to obtain sufficient playback output.

In consideration of the above facts, the present invention aims to provide a speaker device and a speaker system that can suppress howling when using an electronic stethoscope.

A speaker device according to the present invention includes a receiving unit that receives a signal representing an auscultation sound from an electronic stethoscope, and corrects the signal received by the receiving unit so as to suppress the signal level when the signal level is below a predetermined value. The apparatus includes a correction section and an output section that outputs an auscultation sound represented by the corrected signal.

According to the present invention, the reception unit receives a signal representing an auscultation sound from an electronic stethoscope. The correction section corrects the signal received by the reception section so as to suppress the signal level when the signal level is below a predetermined value. Then, the output unit outputs the auscultation sound represented by the corrected signal.

In this way, the signal representing the auscultation sound received from the electronic stethoscope is corrected so as to suppress the signal level when the signal level is below a predetermined value. Thereby, howling can be suppressed when using the electronic stethoscope.

The correction section according to the present invention divides the signal received by the reception section into signals of a plurality of signal bands, and divides the signal of the signal band into signals having a predetermined signal level for each of the plurality of signal bands. When the signal level is below the value, the signal level is corrected to be suppressed, and the output unit outputs an auscultation sound represented by a signal obtained by adding the corrected signals for each of the plurality of signal bands. .

The correction unit according to the present invention can further correct the signal of each of the plurality of signal bands according to human auditory characteristics.

The correction unit according to the present invention divides the signal received by the reception unit into signals of a plurality of signal bands, and divides the signal of the signal band into signals of the signal band according to human auditory characteristics for each of the plurality of signal bands. The output unit can output an auscultation sound represented by a signal obtained by adding the corrected signals to each of the plurality of signal bands.

A speaker system according to the present invention includes an electronic stethoscope that transmits a signal representing auscultation sound, and the above-described speaker device.

According to the present invention, an electronic stethoscope transmits a signal representing an auscultation sound by wireless communication. The receiver receives a signal representing an auscultation sound from the electronic stethoscope. The correction section corrects the signal received by the reception section so as to suppress the signal level when the signal level is below a predetermined value. Then, the output unit outputs the auscultation sound represented by the corrected signal.

In this way, the signal representing the auscultation sound received from the electronic stethoscope is corrected so as to suppress the signal level when the signal level is below a predetermined value. Thereby, howling can be suppressed when using the electronic stethoscope.

As described above, according to the present invention, it is possible to provide a speaker device and a speaker system that can suppress howling when using an electronic stethoscope.

1 is a schematic diagram of a speaker system according to an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of an electronic stethoscope according to an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of a speaker device according to an embodiment of the present invention. This is an example of a bandpass filter. FIG. 3 is a diagram for explaining a method for correcting signals in a signal band according to human auditory characteristics for each of a plurality of signal bands. For each of a plurality of signal bands, a method is provided in which the signal in the signal band is corrected according to human auditory characteristics, and the signal in the signal band is corrected so as to suppress the signal level when the signal level is below a predetermined value. It is a figure for explaining. FIG. 2 is a block diagram showing the configuration of a subharmonic generation section of a speaker device according to an embodiment of the present invention.

Embodiments of the present invention will be described in detail below with reference to the drawings.

<Overview of embodiments of the present invention>
A speaker system using an electronic stethoscope is required to be as small as possible, taking into consideration the installation environment.

Furthermore, since auscultation sounds such as heart sounds include low tones starting from 20 Hz, a speaker device with a wide reproduction band is required.

In addition, since there is a volume adjustment volume on the electronic stethoscope side, in order to obtain appropriate loudness equalization on the speaker device side, it is necessary to adjust the volume on both the electronic stethoscope side and the speaker device side. It is difficult to obtain sound output with good sound quality. Here, loudness equalization means making the sound sound the same regardless of frequency.

For loudness equalization in conventional audio systems, filter characteristics were obtained according to the output level by specifying a reference level between the connected audio devices, but as mentioned above, the volume is interposed between the audio devices. In this case, it is not possible to obtain appropriate loudness equalization.

Therefore, in this embodiment, a bandpass is applied to the sound source signal input to the speaker system into a band with low sensitivity, a band with relatively linear sensitivity, and a band with high sensitivity, based on the equal loudness curve and the characteristics of the speaker system itself. This method uses a filter to divide the band, dynamically expands and compresses the signal level of each band, and obtains a loudness curve that corresponds to the output sound level. Thereby, it is possible to obtain an acoustic output with loudness equalization according to the respective volume adjustment levels on the electronic stethoscope side and the speaker device side. Here, the equal-loudness curve is a contour line that connects maps of frequencies and sound pressures that are perceived as equal sound loudness.

In addition, as a countermeasure against howling, it is possible to use a howling suppressor used in broadcasting equipment, etc., but this method detects the howling frequency and attenuates that frequency with a notch filter, so the attenuated frequency band information about the auscultation sounds is lost.

Therefore, in this embodiment, we will focus on the difference in the volume of sound transmitted to the ears when the chestpiece is placed away from the body and when it is brought into close contact with the body. The principle of a stethoscope is that the diaphragm of the chestpiece is brought into close contact with the desired position to be auscultated with a certain force, and the vibrations of the diaphragm are transmitted to the ear through a rubber tube, so the auscultation sound is small when the diaphragm is not brought into close contact. On the other hand, when the diaphragm of the chest piece is moved away from the body, a howling path is formed from the diaphragm, although the sound is small. Based on these conditions, howling is suppressed by determining a volume threshold based on the difference in volume when the diaphragm of the chest piece is placed away from the body and when it is in close contact with the body, and suppresses the signal level when the volume is below the volume threshold.

In addition, if the volume threshold is determined from the auscultation sound of an electronic stethoscope with the diaphragm held away from the body, the threshold must be set high due to various band noises such as the sound of touching the chest piece or the sound of touching clothes. Even when a chest piece was attached to the body, the signal level could be suppressed. Therefore, in this embodiment, signal level correction for each frequency band by dynamic loudness is used to suppress the signal level for suppressing howling in each band. As a result, practical howling suppression with a low threshold value is possible.

In addition, the electronic stethoscope monitor requires heart sounds that are as low as 20 Hz. However, human ears suddenly find it difficult to hear sounds below 200 Hz, and bass reproduction in small speaker systems is also greatly affected by the room environment, listening distance, and other factors. Therefore, in this embodiment, a bass reproduction technique using harmonics is applied. A signal in the bass band at the reproduction limit of the speaker system is extracted by a bandpass filter, and second and third harmonic bands are extracted from the extracted bass band signal by the bandpass filter and reproduced as auscultation sound. In this way, the auscultation sound is reproduced as a frequency-shifted sound with less discomfort. The reason for using the 2nd and 3rd harmonics is that the nature of the sound is that they are consonants a perfect fifth above the other, and this creates a consonant relationship that is second to the octave relationship, making it possible to reproduce bass sounds with a sense of pitch. It's for a reason.

<Configuration of speaker system according to embodiment of the present invention>
FIG. 1 shows a schematic diagram of a speaker system 100 according to an embodiment of the invention.

As shown in FIG. 1, the speaker system 100 includes an electronic stethoscope 10 and a speaker device 20.

As shown in FIG. 2, the electronic stethoscope 10 includes a chest piece section 30, an audio amplifier 32, a sound quality correction section 34, a volume adjustment section 36, and a wireless communication section 38.

The chest piece part 30 is placed at a part of the subject to be auscultated, and a diaphragm (not shown) of the chest piece part 30 is brought into close contact with the part of the subject with a constant force.

The audio amplifier 32 receives the vibration of the diaphragm of the chest piece section 30 as input, amplifies and outputs a sound source signal representing the vibration of the diaphragm.

The sound quality correction unit 34 performs correction processing on the sound source signal output from the audio amplifier 32 so as to correct the sound quality.

The volume adjustment unit 36 performs adjustment processing on the sound source signal output from the sound quality correction unit 34 so as to adjust the volume in accordance with the operation on the volume adjustment volume on the electronic stethoscope 10 side.

The wireless communication unit 38 transmits the sound source signal output from the volume adjustment unit 36 to the speaker device 20 by wireless communication (eg, Bluetooth (registered trademark)).

As shown in FIG. 3, the speaker device 20 includes a wireless communication section 40 as a reception section, a sound quality adjustment section 42, a volume adjustment section 44, a correction section 46, a subharmonic generation section 48, and an addition section 49. , a power amplifier section 51, and a speaker section 53 as an output section.

The wireless communication unit 40 receives a sound source signal from the electronic stethoscope 10. The sound quality adjustment unit 42 performs adjustment processing on the received sound source signal to adjust (correct) the sound quality. The volume adjustment unit 44 performs adjustment processing on the sound source signal output from the sound quality adjustment unit 42 so as to adjust the volume in accordance with the operation on the volume adjustment volume on the speaker device 20 side.

The correction unit 46 corrects the sound source signal output from the volume adjustment unit 44 so as to suppress the signal level when the signal level is below a predetermined value.

Specifically, the correction unit 46 divides the sound source signal into signals of a plurality of signal bands, and suppresses the signal level of each of the plurality of signal bands when the signal level of the signal band is below a predetermined value. Further, for each of the plurality of signal bands, the signal of the signal band is corrected according to the human auditory characteristics.

More specifically, the sound source signal is divided into a low sensitivity band Low, a relatively linear band Mid-Low, a high sensitivity band Mid-Hi, and an even higher band Hi using a bandpass filter. (See Figure 4).

For each signal band, the signal level of the signal band is corrected according to human auditory characteristics. For example, as shown in FIG. 5, in the band Low where the sensitivity is low, the signal level is corrected so as to increase as the signal level becomes lower, and in the band Mid-Low where the sensitivity is relatively linear, no correction is made. Furthermore, in the high sensitivity band Mid-Hi, the higher the signal level, the more the signal level is corrected to be suppressed, and in the higher band Hi, the lower the signal level, the higher the signal level is corrected.

Further, when correcting the signal level for each signal band, the correction unit 46 corrects the signal level for each signal band so as to suppress the signal level when the signal level is below the threshold value, as shown in FIG. do.

The subharmonic generating section 48 generates a sound source signal to be reproduced as a frequency-shifted auscultation sound from a bass band at the reproduction limit of the speaker device 20.

Specifically, as shown in FIG. 7, the subharmonic generation section 48 includes a non-reproduction low band extraction section 50, a harmonic generation section 52, a second and third harmonic extraction section 54, and an effect level An adjustment section 56 is provided.

The non-reproduction low frequency band extraction unit 50 extracts a low frequency band signal at the reproduction limit of the speaker device 20 from the sound source signal output from the volume adjustment unit 44 using a bandpass filter.

The harmonic generation section 52 generates a harmonic band signal from the bass band signal extracted by the non-reproduction low band extraction section 50.

The second and third harmonic extraction section 54 extracts second and third harmonic band signals from the harmonic band signals output from the harmonic generation section 52 using a bandpass filter.

The effect level adjustment section 56 adjusts the signal level of the signals in the second and third harmonic bands output from the second and third harmonic extraction section 54, and reproduces them as frequency-shifted auscultation sounds. Outputs the sound source signal for.

The adding unit 49 adds the signal corrected for each of the plurality of signal bands by the correcting unit 46 and the sound source signal outputted by the subharmonic generating unit 48 to be reproduced as a frequency-shifted auscultation sound. and output.

The power amplifier section 51 outputs the output of the addition section 49 to the speaker section 53.

The speaker unit 53 outputs auscultation sound from the output of the power amplifier unit 51. Specifically, the speaker section 53 includes a drive circuit that outputs a control signal that vibrates a diaphragm (not shown) of the driver based on a sound source signal, and a drive section that vibrates the diaphragm in accordance with the output of the drive circuit. It is equipped with Here, the driver includes a voice coil and a magnetic circuit. The drive circuit outputs a control signal to the voice coil according to the input sound source signal, and causes the diaphragm of the driver to vibrate using the magnetic circuit.

<Operation of the speaker system according to the embodiment of the present invention>
A user grasps the chest piece portion 30 of the electronic stethoscope 10 and brings the diaphragm of the chest piece portion 30 into close contact with the subject's body part.

The audio amplifier 32 of the electronic stethoscope 10 receives the vibration of the diaphragm of the chest piece part 30 as input, amplifies and outputs a sound source signal representing the vibration of the diaphragm. The sound quality correction unit 34 performs correction processing on the sound source signal output from the audio amplifier 32 so as to correct the sound quality. The volume adjustment unit 36 performs adjustment processing on the sound source signal output from the sound quality correction unit 34 so as to adjust the volume in accordance with the operation on the volume adjustment volume on the electronic stethoscope 10 side.

Then, the wireless communication unit 38 of the electronic stethoscope 10 transmits the sound source signal output from the volume adjustment unit 36 to the speaker device 20 by wireless communication.

Next, the wireless communication unit 40 of the speaker device 20 receives the sound source signal from the electronic stethoscope 10. The sound quality adjustment unit 42 performs a correction process on the received sound source signal so as to correct the sound quality. The volume adjustment unit 44 performs adjustment processing on the sound source signal output from the sound quality adjustment unit 42 so as to adjust the volume in accordance with the operation on the volume adjustment volume on the speaker device 20 side.

Then, the correction unit 46 of the speaker device 20 divides the sound source signal into signals of a plurality of signal bands, and for each of the plurality of signal bands, if the signal level of the signal of the signal band is below a predetermined value, the signal level Further, for each of the plurality of signal bands, the signal in the signal band is corrected in accordance with human auditory characteristics. Further, the subharmonic generation section 48 generates a sound source signal for reproduction as a frequency-shifted auscultation sound from the bass band at the reproduction limit of the speaker device 20.

Then, the adder 49 of the speaker device 20 reproduces the signal corrected for each of the plurality of signal bands by the corrector 46 and the frequency-shifted auscultation sound output by the subharmonic generator 48. The signal obtained by adding the sound source signal of is output. The power amplifier section 51 outputs the output of the addition section 49 to the speaker section 53. The speaker unit 53 outputs auscultation sound from the output of the power amplifier unit 51.

As explained above, according to the speaker system according to the embodiment of the present invention, the signal representing the auscultation sound received from the electronic stethoscope is corrected so as to suppress the signal level when the signal level is below a predetermined value. This makes it possible to suppress howling when using the electronic stethoscope.

When the signal level is lower than the volume threshold determined based on the volume when the chestpiece is applied to the body and the volume when it is separated from the body, the audio information is corrected to suppress the signal level. It is possible to suppress howling without causing any loss. At this time, the band is divided and the signal level is corrected to suppress howling, so it is possible to prevent auscultation of sounds other than heart sounds.

In addition, by dividing the bands based on the equal loudness curve (human sensitivity) and correcting the signal representing the auscultation sound in each divided band, an appropriate loudness curve can be obtained and the sound It is also possible to reproduce auscultation sounds (with a wide range of reproduction frequencies).

In addition, by generating and reproducing harmonics (overtones) in the low frequency range (e.g. 20Hz) that are difficult for humans to hear, it is possible to reproduce low frequency sounds that should not be included in auscultation sounds. can do.

Note that the present invention is not limited to the embodiments described above, and various modifications and applications are possible without departing from the gist of the present invention.
For example, a signal representing auscultation sounds may be sent to an electronic stethoscope by wired communication.

10 Electronic stethoscope 20 Speaker device 30 Chestpiece section 32 Audio amplifier 34 Sound quality correction section 36 Volume adjustment section 38 Wireless communication section 40 Wireless communication section 42 Sound quality adjustment section 44 Volume adjustment section 46 Correction section 48 Subharmonic generation section 49 Addition section 50 Non-reproduction low band extraction section 51 Power amplifier section 52 Harmonic generation section 53 Speaker section 54 Second and third harmonic extraction section 56 Effect level adjustment section 100 Speaker system

Claims (5)

a receiving unit that receives a signal representing an auscultation sound from an electronic stethoscope;
a correction unit that corrects the signal received by the reception unit so as to suppress the signal level when the signal level is below a predetermined value;
an output unit that outputs an auscultation sound represented by the corrected signal;
Speaker equipment including. The correction unit is
dividing the signal received by the receiving unit into signals of a plurality of signal bands;
for each of the plurality of signal bands, correcting the signal in the signal band so as to suppress the signal level when the signal level is below a predetermined value;
The speaker device according to claim 1, wherein the output section outputs an auscultation sound represented by a signal obtained by adding signals corrected for each of the plurality of signal bands. The correction unit is
3. The speaker device according to claim 2, further comprising correcting the signal of each of the plurality of signal bands according to human auditory characteristics. The correction unit is
dividing the signal received by the receiving unit into signals of a plurality of signal bands;
For each of the plurality of signal bands, correcting the signal in the signal band according to human auditory characteristics,
The speaker device according to claim 1, wherein the output section outputs an auscultation sound represented by a signal obtained by adding signals corrected for each of the plurality of signal bands. an electronic stethoscope that transmits a signal representing auscultation sounds;
The speaker device according to any one of claims 1 to 4,
Speaker system including.