Bone conduction earphone and method for using bone conduction earphone

Abstract

An ear insertion part 11 has a size capable of being inserted into a recess of a concha cavity of a user. A signal reception part 12 is provided inside the ear insertion part and receives an input audio signal. A first vibration generation source 13 is provided inside the ear insertion part and has a vibration characteristic in which the amplitude exhibits a peak at a predetermined first frequency with respect to an input audio signal in a predetermined frequency band. A second vibration generation source 14 is provided inside the ear insertion part so as to be closer to cartilage existing around the concha cavity than the first vibration generation source when the ear insertion part is brought into pressure contact with the concha cavity. The second vibration generation source has a vibration characteristic in which the amplitude exhibits a peak at a predetermined second frequency higher than the first frequency with respect to the input audio signal in the frequency band, and can vibrate independently of the first vibration generation source. A vibration control unit 15 simultaneously inputs the received input audio signal to the first vibration generation source and the second vibration generation source.

Description

Bone conduction earphone and method of using bone conduction earphone

[0001] The present invention relates to a bone conduction earphone and a method of using the bone conduction earphone.

[0002] Conventionally, there are various technologies related to earphones (also referred to as ear inserts, piezoelectric vibration devices, etc.) that enhance sound quality. For example, Japanese Patent No. 7462894 (Patent Document 1) patented by the present applicant discloses a bone conduction earphone including a sound emitting portion, a control circuit, a vibration portion, and clay. Also, Japanese Patent Translation Publication No. 2021-527364 (Patent Document 2) discloses a bone conduction speaker including a driving device and a panel. The driving device generates a driving force located in a straight line. The panel is connected to the driving device in a transmissible manner, and all or part of the panel is configured to contact the user's body in order to conduct sound, and the region where the panel interacts with the user's body has a normal line that is not parallel to the straight line. Thereby, it is said that the sound quality of the bone conduction speaker or the bone conduction earphone can be improved.

[0003] Also, Japanese Patent Application Laid-Open No. 2012-222682 (Patent Document 3) discloses a bone conduction earphone including a bone conduction vibration portion, a front-side convex portion, and a back-side convex portion. Also, Japanese Patent Application Laid-Open No. 2018-191140 (Patent Document 4) discloses a piezoelectric vibration device including a plurality of piezoelectric vibrators, a support portion, and a vibration transmission portion. Also, Japanese Patent Application Laid-Open No. 2017-076919 (Patent Document 5) discloses an earphone configured to support two portions that move relative to each other in the same electromagnetic vibrator with an elastic body interposed therebetween. On the other hand, although it is not in the technical field of earphones, as a device using a plurality of vibrators, Japanese Patent Application Laid-Open No. 2020-141354 (Patent Document 6) discloses an underwater ultrasonic vibrator used for a transceiver.

[0004] Japanese Patent No. 7462894, Japanese Patent Translation Publication No. 2021-527364, Japanese Patent Application Laid-Open No. 2012-222682, Japanese Patent Application Laid-Open No. 2018-191140, Japanese Patent Application Laid-Open No. 2017-076919, Japanese Patent Application Laid-Open No. 2020-141354

[0005] Bone conduction earphones use a vibration source that vibrates with an amplitude corresponding to the audio signal. This vibration source refers to the element that generates vibration, and can be a diaphragm, vibrator, or vibration element. Specifically, examples include piezoelectric ceramic vibrators, electromagnetic vibrators, and supermagnetostrictive vibrators.

[0006] Generally, vibration sources exhibit vibration characteristics that show a peak in amplitude (output) at a predetermined frequency, and these vibration characteristics vary greatly depending on the material, structure, and type of the vibration source. For example, if the peak of the vibration characteristic is on the low-frequency side, and the input audio signal is also on the low-frequency side, the vibration source will vibrate with a large amplitude, making low-frequency sounds easier for the user to perceive. Here, speech recognition means that the user recognizes the sound, and language comprehension means that the user recognizes the sound and understands the text from the sound to comprehend the language. On the other hand, if the input audio signal is on the high-frequency side, the vibration source will vibrate with a small amplitude, making high-frequency sounds difficult for the user to perceive, and the user will not be able to understand and comprehend the language of the speech. In other words, with bone conduction earphones, the sounds that the user can perceive vary depending on the vibration characteristics of the vibration source, and there is a problem that the user may not be able to comprehend the language.

[0007] In particular, the vibration characteristics of a vibration source typically peak at low frequencies. Therefore, with high-frequency audio signals, the amplitude of the vibration source becomes small, often making it difficult for users to understand the language. For example, the characters that make up a language generally consist of vowels and consonants. In Japanese, vowels are the characters "a," "i," "u," "e," and "o," while consonants are all characters other than vowels. Similarly, in English, vowels are the characters "a," "e," "i," "o," and "u," while consonants are all characters other than vowels. Generally, in other languages ​​as well, vowels are at low frequencies and consonants are at high frequencies. As a result, conventional bone conduction earphones have difficulty reproducing the vibrations of consonants in the high-frequency range, making it difficult for users to recognize consonants and understand the language. Therefore, there has been a need for bone conduction earphones that have a large amplitude regardless of the frequency range of the audio, allowing users to recognize the audio and understand the language.

[0008] In particular, for users with hearing impairments or hearing loss, it is crucial to accurately transmit both high-frequency and low-frequency sounds. Furthermore, even just being able to clearly hear high-frequency consonants can broaden the range of sounds that people with hearing impairments or hearing loss can understand, improving their comprehension of external sounds.

[0009] Here, the technology described in Reference 1 includes a vibration source and a vibration control unit, but it cannot solve the problem of improving sound quality by providing two or more vibration sources. Furthermore, although the technology described in Reference 2 generates two vibrations using two drive units, the drive units are mechanically connected to the panel via a first transmission component. The drive units are also mechanically connected to a partition plate provided in the cavity via a second transmission component. Therefore, the vibrations of these two drive units are transmitted to the same panel, and through this panel, they are transmitted to the skin and bones of the human body. In other words, due to the presence of the panel, it is ultimately just a monaural transmission where vibration is caused by a single vibrator with a single vibration characteristic.

[0010] Furthermore, in the technology described in Patent Document 3, the bone conduction vibrator is a single piezoelectric ceramic. Furthermore, in the technology described in Patent Document 4, the overall vibration is synchronized by connecting (contacting) multiple piezoelectric vibrators, thereby increasing the output that results in sound. Furthermore, in the technology described in Patent Document 5, the extraction of vibration is made easier by using the same electromagnetic vibrator. Furthermore, in the technology described in Patent Document 5, a desired range of motion can be secured by stacking a low-frequency piezoelectric vibrator and a composite vibrator. However, in the technologies described in Patent Documents 3-5, since a single vibrator or multiple identical vibrators are used, there is a high possibility that a single vibration characteristic is exhibited as a whole, and therefore the above-mentioned problems cannot be solved. Furthermore, in the technology described in Patent Document 6, the vibration intensity is increased as a whole by stacking multiple different vibrators, so it is no different from the vibration characteristic of a single vibrator, and therefore the above-mentioned problems cannot be solved.

[0011] Therefore, the present invention has been made to solve the aforementioned problems, and aims to provide bone conduction earphones and a method for using bone conduction earphones that can accurately reproduce sound in any frequency band and improve sound quality.

[0012] The bone conduction earphone according to the present invention is a bone conduction earphone having at least two vibration sources, comprising: a sound collecting unit; an ear insertion unit; a signal receiving unit; a first vibration source; a second vibration source; and a vibration control unit. The sound collecting unit collects external sound and converts it into an input audio signal corresponding to the external sound. The ear insertion unit is sized to be inserted into the cavity of the user's concha. The signal receiving unit is provided inside the ear insertion unit and receives the converted input audio signal. The first vibration source is provided inside the ear insertion unit and has vibration characteristics in which the amplitude peaks at a predetermined first frequency for an input audio signal in a predetermined frequency band. The second vibration source is provided inside the ear insertion unit so as to be closer to the cartilage surrounding the concha than the first vibration source when the ear insertion unit is pressed against the concha, and has vibration characteristics in which the amplitude peaks at a predetermined second frequency higher than the first frequency for an input audio signal in the frequency band, and is capable of vibrating independently of the first vibration source. The vibration control unit simultaneously inputs the received input audio signal to the first vibration source and the second vibration source. The bone conduction earphone according to the present invention inserts one end of the ear insertion part into the recess of the user's concha, presses the ear insertion part against the concha between the user's tragus and antitragus, and simultaneously vibrates the first vibration source and the second vibration source based on the external sound, thereby independently transmitting the vibration of the first vibration source and the vibration of the second vibration source to the user's external auditory canal and surrounding cartilage.

[0013] Furthermore, the method of using the bone conduction earphone according to the present invention is a method of using a bone conduction earphone, comprising a pressing step and a vibration step. The pressing step involves inserting one end of the ear insertion part into the recess of the user's concha, and pressing the ear insertion part against the concha between the user's tragus and antitragus. The vibration step involves simultaneously vibrating the first vibration source and the second vibration source based on the external sound, and independently transmitting the vibration of the first vibration source and the vibration of the second vibration source to the user's external auditory canal and surrounding cartilage.

[0014] According to the present invention, it is possible to accurately reproduce sound in any frequency band and improve sound quality.

[0015] This is a plan view and a front view cross-sectional view showing an example of a bone conduction earphone according to an embodiment of the present invention. This is a graph showing an example of the output sound amplitude of the conventional technology and the output sound amplitude of the present invention in relation to an input sound signal. This is a front view showing an example of inserting a bone conduction earphone according to an embodiment of the present invention into the cavity of the user's concha. This is a schematic diagram showing an example of the output sound amplitude of the conventional technology in relation to an input sound signal including low-frequency and high-frequency sounds. This is a schematic diagram showing an example of the output sound amplitude of the present invention in relation to an input sound signal including low-frequency and high-frequency sounds. This is a front view cross-sectional view (Figure 6A) showing an example of a case where the arrangement of the first vibration source and the second vibration source is changed, and a front view cross-sectional view (Figure 6B) showing an example of a case where the size of the first vibration source and the second vibration source is changed. This is a plan view and a front view cross-sectional view showing an example of a configuration in which the arrangement of the first vibration source and the second vibration source is changed. This is a plan view and a front view cross-sectional view showing an example of a configuration in which the arrangement is changed when the size of the first vibration source and the second vibration source is changed. Figure 12A shows an example of a case where a third vibration source is further provided, along with a plan view cross-sectional view, a front view cross-sectional view, and a graph of the output sound amplitude; Figure 12B shows an example of a case where a third vibration source and a fourth vibration source are further provided. Figure 12A shows an example of a bone conduction earphone according to an embodiment of the present invention in which clay is attached to the outer surface of the ear insertion part. Figure 12B shows an example of a bone conduction earphone according to an embodiment of the present invention in which a C-shaped neckband is attached. Figure 12A shows an example of a bone conduction earphone according to an embodiment of the present invention in which an O-shaped pendant band is attached, and Figure 12B shows an example of a case where the sound collection part and the ear insertion part are separated and sound signals are transmitted and received wirelessly. Figure 12B shows an example of a bone conduction earphone according to an embodiment of the present invention in which a ring-shaped outer frame is attached to the outer circumference of the ear insertion part. Figure 12B shows a schematic diagram of a hypothetical bone conduction earphone embodiment 1 and experimental conditions. Figure 12B shows an example of the vibration characteristics of the first vibration source, the vibration characteristics of the second vibration source, the theoretically combined theoretical vibration characteristics, and the experimental vibration characteristics obtained by analysis.

[0016] The following describes embodiments of the present invention with reference to the attached drawings to facilitate understanding of the invention. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the invention.

[0017] A bone conduction earphone 1 according to an embodiment of the present invention is a bone conduction earphone having at least two vibration sources, and as shown in Figure 1, comprises a sound collection unit 10, an ear insertion unit 11, a signal receiving unit 12, a first vibration source 13, a second vibration source 14, and a vibration control unit 15.

[0018] Here, the sound collection unit 10 collects external sound and converts it into an input audio signal corresponding to that external sound. The sound collection unit 10 can be, for example, a microphone.

[0019] Furthermore, the ear insertion portion 11 is sized to be inserted into the recess of the user's concha. Here, the ear insertion portion 11 is configured in an elliptical disc shape, as shown in Figure 1, for example. Elliptical disc shape means an elliptical shape with a certain thickness, which allows it to be inserted into the recess of the user's concha.

[0020] Furthermore, the signal receiving unit 12 is located inside the ear insertion unit 11 and receives the converted input audio signal. Here, if the signal receiving unit 12 is connected to the sound collection unit 10 by wireless communication, as shown in Figure 1, for example, the signal receiving unit 12 can receive the input audio signal from the sound collection unit 10 via wireless communication. Here, wireless communication can be, for example, Bluetooth®. Alternatively, if the signal receiving unit 12 is connected to the sound collection unit 10 by wired communication, the signal receiving unit 12 can receive the input audio signal from the sound collection unit 10 via electrical wires.

[0021] Furthermore, the first vibration source 13 is provided inside the ear insertion part 11 and has a vibration characteristic V1 in which the amplitude (output) Amplitude (mm) shows a peak at a predetermined first frequency f1 (Hz) for an input audio signal in a predetermined frequency band f. Here, the vibration source refers to an element that generates vibration, and corresponds to a diaphragm, vibrator, vibrating element, etc. Also, if the input audio signal has a constant amplitude Amplitude (mm) in the range of a predetermined frequency f (for example, 10 Hz to 6000 Hz), as shown in Figure 2, the first vibration source 13 will receive the input audio signal and output a vibration with an amplitude Amplitude (mm) that shows a peak at the first frequency f1 (Hz).

[0022] In Figure 2, the vibrating surface of the first vibration source 13 is positioned facing upwards towards the ear insertion portion 11. Here, the vibrating surface is the surface that outputs vibration, and typically, a vibration source has a vibrating surface that generates vibration in one direction.

[0023] Furthermore, the second vibration source 14 is provided inside the ear insertion part 11 so as to be closer to the cartilage surrounding the concha of the ear than the first vibration source 13 when the ear insertion part 11 is pressed against the concha of the ear. It has a vibration characteristic V2 in which the amplitude Amplitude (mm) of the input audio signal in the frequency band shows a peak at a predetermined second frequency f2 (Hz) that is higher than the first frequency f1 (Hz), and it can vibrate independently of the first vibration source 13. Here, if the input audio signal has a constant amplitude Amplitude (mm) in the range of a predetermined frequency f (10 Hz to 6000 Hz), as described above, the second vibration source 14 receives the input audio signal and outputs a vibration with an amplitude Amplitude (mm) that peaks at the second frequency f2 (Hz). Also, in Figure 2, the vibration surface of the second vibration source 14 is positioned facing the same direction as the vibration surface of the first vibration source 13.

[0024] Here, the statement that the second vibration source 14 vibrates independently of the first vibration source 13 means that the first vibration source 13 and the second vibration source 14 vibrate separately without contact with each other. If the first vibration source 13 and the second vibration source 14 are located close together, the vibrations of the first vibration source 13 and the vibrations of the first vibration source 14 may partially interfere with and cancel each other out. However, since the first vibration source 13 and the second vibration source 14 vibrate in different and unique frequency bands, the overall output vibration will have a broader frequency band.

[0025] Then, as shown in Figure 2, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, the vibration characteristics V1 of the first vibration source 13 and the vibration characteristics V2 of the second vibration source 14 overlap with each other to form a composite wave, and as a whole, a vibration characteristic V12 with a wider frequency band is formed.

[0026] This is called stagger tuning in the field of electronic circuits. Stagger tuning means expanding the frequency range to obtain the required frequency band by linking multiple tuning circuits with different frequency bands. In this invention, we have applied this phenomenon, which is in the field of acoustics rather than electronic circuits, to bone conduction earphones.

[0027] As a result, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, the frequency band in which the amplitude Amplitude (mm) exists is broadened compared to when the first vibration source 13 and the second vibration source 14 vibrate individually. This makes it possible to increase the amplitude Amplitude (mm) and cause vibration for any frequency band of sound.

[0028] Furthermore, the vibration control unit 15 simultaneously inputs the received audio signal to the first vibration source 13 and the second vibration source 14. This makes it possible to vibrate the first vibration source 13 and the second vibration source 14 at the same time.

[0029] As shown in Figure 3, the bone conduction earphone 1 according to an embodiment of the present invention has one end 11a of the ear insertion part 11 inserted into the cavity of the user's concha cavity CC, and the ear insertion part 11 is pressed against the concha cavity CC between the user's tragus T and antitragus A, causing the first vibration source 13 and the second vibration source 14 to vibrate simultaneously based on external sound. The ear canal EC is located deep inside the cavity of the concha cavity CC. The ear canal EC is connected to the cochlea, a sensory organ that controls hearing, and cartilage Ca, such as tragus cartilage and auricular cartilage, is present around the ear canal EC, and vibrations are transmitted from the ear canal EC to the cartilage Ca and then to the cochlea. In this embodiment of the present invention, the bone conduction earphone 1 independently transmits the vibrations of the first vibration source 13 and the vibrations of the second vibration source 14 to the user's external auditory canal EC and surrounding cartilage Ca.

[0030] This makes it possible to accurately reproduce sound in any frequency band and improve sound quality. Specifically, as explained in Figure 2, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, a vibration characteristic V12 with a wide frequency band is formed. This vibration characteristic V12 is important.

[0031] For example, as shown in Figure 4, in the conventional technology, if an input audio signal having various frequency bands is vibrated only by the first vibration source 13, the peak of the first frequency f1 (Hz) in the vibration characteristic V1 of the first vibration source 13 is biased towards the low frequency side. As a result, the output audio amplitude of the first vibration source 13 becomes larger only on the low frequency side. In other words, the output audio amplitude decreases sharply on the high frequency side compared to the input audio signal. For example, when the first vibration source 13 of the ear insertion part 11 vibrates while pressed against the concha cavity CC, the vibration is transmitted to the external auditory canal EC and surrounding cartilage Ca, but the amplitude of vibration on the high frequency side decreases sharply, leaving only the amplitude of vibration on the low frequency side. Therefore, when a user hears this, for example, only the low-frequency sounds become louder, specifically, only the vowel sounds become louder. As a result, the user perceives only the vowels as louder, and sounds containing consonants become difficult to understand. In other words, even if users can recognize vowel sounds, they cannot recognize consonant sounds, and therefore cannot understand spoken language.

[0032] Furthermore, in conventional technology, if an input audio signal having various frequency bands is vibrated only by the second vibration source 14, the peak of the second frequency f2 (Hz) in the vibration characteristic V2 of the second vibration source 14 is biased towards the high-frequency side. As a result, the output audio amplitude of the second vibration source 14 becomes larger only on the high-frequency side. In other words, the output audio amplitude decreases sharply on the low-frequency side compared to the input audio signal. For example, when the second vibration source 14 of the ear insertion part 11 vibrates while pressed against the concha cavity CC, the vibration is transmitted to the external auditory canal EC and surrounding cartilage Ca, but the amplitude of vibration on the low-frequency side decreases sharply, leaving only the amplitude of vibration on the high-frequency side. Therefore, when a user listens to this, for example, only the high-frequency sounds become louder, and then only the consonant sounds become louder. In this case, the user perceives only the consonants as louder, and it becomes difficult to understand sounds that include vowels.

[0033] Therefore, as shown in Figure 5, in the present invention, when an input audio signal having various frequency bands is simultaneously vibrated by the first vibration source 13 and the second vibration source 14, the overall vibration characteristic V12 has a large amplitude over a wide frequency range, so the overall output audio amplitude is large at both low and high frequencies. In other words, the output audio amplitude is reproduced with a waveform equivalent to the input audio signal, without any decrease in amplitude at either the low or high frequency side compared to the input audio signal. For example, when the first vibration source 13 and the second vibration source 14 of the ear insertion part 11 vibrate while pressed against the concha CC, the vibration is transmitted to the external auditory canal EC and surrounding cartilage Ca. However, since the first vibration source 13 excels at low-frequency vibrations and the second vibration source 14 excels at high-frequency vibrations, neither the low-frequency nor the high-frequency vibrations decrease. Therefore, when a user hears this, they perceive it as a loud sound regardless of whether it's a low or high frequency, making it possible to clearly recognize both vowels and consonants, and thus clearly hear language from the sounds of vowels and consonants. This makes it possible to accurately reproduce sounds in any frequency range, thereby improving sound quality.

[0034] Here, generally, high-frequency vibrations are more easily attenuated than low-frequency vibrations, as the amount of transmissive material increases. Therefore, in the present invention, as shown in Figure 6A, inside the ear insertion part 11, when worn in the user's concha (CC), the second vibration source 14, which is responsible for high-frequency vibrations, is positioned closer to the cartilage Ca than the first vibration source 13, which is responsible for low-frequency vibrations. By doing so, the vibrations of the second vibration source 14 are transmitted to the cartilage Ca before the vibrations of the first vibration source 13, thereby minimizing the attenuation of the vibrations of the second vibration source 14 and delivering highly reproducible sound to the user. Furthermore, by positioning the second vibration source 14 closer to the cartilage Ca, it becomes possible to transmit high-frequency vibrations to the cochlea as much as possible. In other words, while high-frequency sounds were previously difficult to recognize as speech, in the present invention, high-frequency sounds can also be clearly recognized, allowing users who seek high-frequency sounds to accurately hear language.

[0035] In this invention, the first vibration source 13 and the second vibration source 14 are vibrated simultaneously, and their respective vibrations are transmitted independently to the user's external auditory canal EC and surrounding cartilage Ca. In conventional technology, a single vibrator is usually used, so the vibration characteristics of that vibrator directly limit the frequency band, resulting in poor sound reproduction and degraded sound quality. In this invention, two first vibration sources 13 and second vibration sources 14 with different vibration characteristics are vibrated independently, and the first vibration source 13 and the second vibration source 14 are vibrated simultaneously in response to the input sound signal, and these vibrations are transmitted independently to the user's external auditory canal EC and surrounding cartilage Ca. As a result, as shown in Figure 2, in the user's cochlea, the vibration characteristics V1 of the first vibration source 13 and the vibration characteristics V2 of the second vibration source 14 overlap with each other to form a composite wave, and as a whole, it sounds as if a vibration characteristic V12 with a wider frequency band has been formed.

[0036] It is important to note that in this invention, the vibrations of the first vibration source 13 and the second vibration source 14 are transmitted independently to the user's external auditory canal EC and surrounding cartilage Ca, thereby creating a composite wave of vibration characteristics that the user can hear. In other words, in this invention, two speakers with different vibration characteristics vibrate simultaneously to achieve stereo transmission, allowing the user to hear sound. By achieving this stereo transmission, bone conduction earphones 1 can accurately reproduce sounds of any frequency range, thereby improving sound quality.

[0037] Furthermore, this invention is not a technology that simultaneously vibrates multiple transducers and combines the vibrations of each transducer into a single vibration to transmit to the user's external auditory canal (EC) and surrounding cartilage (Ca). In this case, the vibration characteristics heard by the user will not be like a composite wave as described above, but will be biased towards a single vibration characteristic, and ultimately it will only be vibrating with a single transducer that has a single vibration characteristic. In other words, this is merely monaural transmission where a speaker with a single vibration characteristic vibrates and the sound is heard, and most conventional technologies are monaural transmissions.

[0038] In the present invention, stereo transmission is achieved through the above-described configuration, enabling the reproduction of a wide frequency range of sound and improved sound quality that cannot be achieved with conventional technology. In particular, the attenuation of vibrations from the second vibration source 14 affects the reproducibility of sound and the improvement of sound quality in stereo transmission, so the arrangement of the first vibration source 13 and the second vibration source 14 is important. In other words, in the present invention, the second vibration source 14 is provided inside the ear insertion part 11 so that it is closer to the cartilage Ca than the first vibration source 13, thereby suppressing the attenuation of vibrations from the second vibration source 14 and achieving stereo transmission.

[0039] Incidentally, there are no particular limitations on the vibration capabilities of the first vibration source 13 and the second vibration source 14, and they are appropriately selected according to the type of vibration source. Here, for example, as shown in Figure 6B, it is preferable that the maximum amplitude of the second vibration source 14 is designed to be greater than or equal to the maximum amplitude of the first vibration source 13. Here, the maximum amplitude of the vibration source means the maximum displacement obtained by subtracting the minimum value from the maximum value of the amplitude of the vibration of the vibration source. This makes it possible to suppress the attenuation of vibrations on the high-frequency side and improve the reproducibility of sound.

[0040] In other words, as described above, since high-frequency vibrations are more easily attenuated than low-frequency vibrations, the maximum amplitude of the second vibration source 14, which is responsible for high-frequency vibrations, is set to be greater than or equal to the maximum amplitude of the first vibration source 13, which is responsible for low-frequency vibrations, thereby reinforcing the high-frequency vibrations in advance. As a result, when the vibrations of the second vibration source 14 and the first vibration source 13 are transmitted to the external auditory canal EC of the concha CC, even if the vibration of the second vibration source 14 is attenuated, it can be made to be about the same as the vibration of the first vibration source 13, thereby delivering a highly reproducible sound to the user.

[0041] Incidentally, in the present invention, as long as the second vibration source 14 is located inside the ear insertion portion 11 so as to be closer to the cartilage Ca than the first vibration source 13, there are no particular limitations on the arrangement of the first vibration source 13 and the second vibration source 14, and a wide variety of configurations and arrangements can be realized.

[0042] For example, in FIG. 1, the first vibration source 13 and the second vibration source 14 are configured to be arranged side by side in a direction perpendicular to the vibration surface. However, this is not the only case. For example, as shown in FIG. 7, inside the ear insertion part 11, the first vibration source 13 and the second vibration source 14 may be arranged such that their respective vibration surfaces are arranged side by side in the horizontal direction without contacting each other, or the first vibration source 13 and the second vibration source 14 may be arranged such that they partially overlap in the upper and lower spaces.

[0043] Also, as shown in FIG. 7, inside the ear insertion part 11, the first vibration source 13 and the second vibration source 14 may be configured to be arranged such that their respective vibration surfaces are inclined at a predetermined inclination angle α (degrees) facing outward. Note that there is no particular limitation on the inclination angle α formed between the vibration surface of the first vibration source 13 and the vibration surface of the second vibration source 14, and for example, it is set within the range of 0 degrees to 180 degrees.

[0044] Here, if the inclination angle α is 180 degrees, the vibration surfaces of the first vibration source 13 and the second vibration source 14 are arranged side by side in the horizontal direction and facing the same direction. Also, if the inclination angle α is 90 degrees, the vibration surface of the first vibration source 13 is arranged side by side in a direction perpendicular to the vibration surface of the second vibration source 14. Also, if the inclination angle α is 0 degrees, the vibration surface of the first vibration source 13 is arranged side by side in the horizontal direction with respect to the vibration surface of the second vibration source 14 and facing different directions.

[0045] Also, as shown in FIG. 7, inside the ear insertion part 11, the first vibration source 13 and the second vibration source 14 may be configured to be arranged such that their respective vibration surfaces are arranged side by side parallel facing outward. Also, as shown in FIG. 7, inside the ear insertion part 11, the first vibration source 13 and the second vibration source 14 may be configured to be arranged such that their respective vibration surfaces are arranged side by side in a perpendicular direction. Here, in FIG. 7, the vibration surface of the first vibration source 13 is arranged side by side in a direction perpendicular to the vibration surface of the second vibration source 14 near the lower part of the central part of the vibration surface of the second vibration source 14, but this is not limited thereto.

[0046] Here, in the present invention, when the maximum amplitude of the second vibration generating source 14 is designed to be greater than or equal to the maximum amplitude of the first vibration generating source 13, the arrangement of the second vibration generating source 14 and the first vibration generating source 13 does not need to be particularly limited, and various configurations and arrangements can be realized.

[0047] For example, as shown in FIG. 8, inside the ear insertion part 11, the second vibration generating source 14 may be arranged above the first vibration generating source 13, and the vibration surfaces of the second vibration generating source 14 may be arranged parallel to the vibration surface of the first vibration generating source 13.

[0048] Here, the first vibration generating source 13 may be arranged overlapping in the vertical space with respect to the second vibration generating source 14, or the first vibration generating source 13 may be arranged overlapping only partially in the vertical space with respect to the second vibration generating source 14, or it may be arranged adjacent to the second vibration generating source 14 without overlapping in the vertical space.

[0049] Also, as shown in FIG. 8, inside the ear insertion part 11, the second vibration generating source 14 may be arranged above the first vibration generating source 13, and the first vibration generating source 13 and the second vibration generating source 14 may be arranged with their respective vibration surfaces perpendicular to each other.

[0050] Also, as shown in FIG. 8, inside the ear insertion part 11, the second vibration generating source 14 may be arranged inclined at a predetermined inclination angle α above the first vibration generating source 13, and the vibration surfaces of the first vibration generating source 13 and the second vibration generating source 14 may be arranged parallel to each other in the same direction such that the inclination angle α between the vibration surfaces of the first vibration generating source 13 and the second vibration generating source 14 is an acute angle.

[0051] By the way, the sound collecting part 10 is not particularly limited. For example, in addition to a microphone, it may be a sound collecting device that collects music or voices such as a music player or a radio.

[0052] Also, the shape of the ear insertion part 11 is appropriately designed and changed according to the configuration and arrangement of the first vibration generating source 13 and the second vibration generating source 14. As shown in FIG. 1, it may be an elliptical disk shape, or as shown in FIG. 5, it may be cylindrical or hemispherical.

[0053] Furthermore, there are no particular limitations on the size of the ear insertion portion 11, but it is preferable that, for example, the length be in the range of 1.0 cm to 3.0 cm, the width be in the range of 0.5 cm to 2.0 cm, and the thickness be in the range of 0.5 cm to 2.0 cm.

[0054] Furthermore, there are no particular limitations on the material of the ear insertion part 11, but it is preferable that it be made of a soft or elastic material. In particular, since the present invention independently vibrates two first vibration sources 13 and a second vibration source 14 with different vibration characteristics, for example, the ear insertion part 11 can be made of a soft silicone material, and the first vibration source 13 and the second vibration source 14 can be built into the ear insertion part 11.

[0055] Furthermore, there are no particular limitations on the configuration of the signal receiving unit 12. For example, it may be an electrical circuit that receives the input audio signal, or it may also include an adjustment circuit to adjust the magnitude of the input audio signal, a switch circuit to control the power on and off, a filter circuit to block noise signals contained in the input audio signal, or a combination thereof.

[0056] Furthermore, there are no particular limitations on the types of the first vibration source 13 and the second vibration source 14, but examples include piezoelectric ceramic vibrators, electromagnetic vibrators, and supermagnetostrictive vibrators. Also, the first vibration source 13 and the second vibration source 14 may be of the same type or different types. Furthermore, there are no particular limitations on the shapes of the first vibration source 13 and the second vibration source 14, but for example, they may be small cylindrical shapes, shapes with elongated pins connected to a disc, or elongated shapes. In addition, if the shapes of the first vibration source 13 and the second vibration source 14 are such that they can be inserted into the user's ear canal, it is possible to transmit the vibrations of the first vibration source 13 and the second vibration source 14 to the inside of the ear more clearly. Furthermore, the shapes of the first vibration source 13 and the second vibration source 14 may be general shapes such as cylinders, polygonal prisms, cylindrical bodies, polygonal tubes, cones, and polygonal pyramids, or they may be shapes with dimensions of 1 cm or less in length, width, and height, similar to the size of a typical earphone.

[0057] Furthermore, there are no particular limitations on the configuration of the first vibration source 13 and the second vibration source 14. For example, if the first vibration source 13 is a first diaphragm and the second vibration source 14 is a second diaphragm, the first vibration source 13 and the second vibration source 14 may be configured by combining a first device capable of vibrating with the first diaphragm and a second device capable of vibrating with the second diaphragm. Alternatively, the first vibration source 13 and the second vibration source 14 may be configured by incorporating the first diaphragm and the second diaphragm into a single device and configuring it so that the first diaphragm and the second diaphragm vibrate independently.

[0058] Furthermore, there are no particular limitations on the configuration of the vibration control unit 15, but for example, it may be further equipped with adjustment circuits, switch circuits, filter circuits, etc., which do not have a signal receiving unit 12. Also, the vibration control unit 15 may be further equipped with an equalizer to adjust the vibration of the second vibration source 14 and the vibration of the first vibration source 13. For example, the vibration control unit 15 can adjust the vibration on the high-frequency side and the vibration on the low-frequency side by using an equalizer to strengthen the input audio signal to the second vibration source 14 on the high-frequency side and weaken the input audio signal to the first vibration source 13 on the low-frequency side.

[0059] Furthermore, while the present invention is configured to include two vibration sources, a first vibration source 13 and a second vibration source 14, which have different frequency bands, the invention is not limited to this configuration, and may be configured to include three or more different vibration sources.

[0060] For example, as shown in Figure 9, the third vibration source 16 is provided inside the ear insertion part 11 and has vibration characteristics V3 in which the amplitude Amplitude (mm) of the input audio signal in the frequency band shows a peak at a predetermined third frequency f3 (Hz) that is higher than the second frequency f2 (Hz), and can vibrate independently of the first vibration source 13 and the second vibration source 14. Here, the second vibration source 14 is on the higher frequency side than the first vibration source 13, and the third vibration source 16 is on the higher frequency side than the second vibration source 14. Therefore, inside the ear insertion part 11, when worn in the user's concha (CC), the third vibration source 16 is positioned closer to the cartilage Ca than the second vibration source 14, and the second vibration source 14 is positioned closer to the cartilage Ca than the first vibration source 13. In other words, in the present invention, the vibration sources on the higher frequency side of the three vibration sources are positioned sequentially closer to the cartilage.

[0061] As a result, when the first vibration source 13, the second vibration source 14, and the third vibration source 16 vibrate simultaneously, the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, and the vibration characteristics V3 of the third vibration source 16 overlap with each other to form a composite wave, and as a whole, a vibration characteristic V123 with an even wider frequency band is formed. This makes it possible to broaden the reproducible frequency band and improve sound quality.

[0062] Here, the third vibration source 16 vibrates independently of the first vibration source 13 and the second vibration source 14, and the high-frequency vibration sources are arranged sequentially to approach the cartilage. As long as this configuration is not limited, a wide variety of configurations and arrangements can be realized. For example, the third vibration source 16 can be arranged in a wide variety of positions relative to the first vibration source 13 and the second vibration source 14, as described above. For example, the vibration surface of the third vibration source 16 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the first vibration source 13, and this inclination angle α is set within the range of 0 to 180 degrees, as described above. Similarly, the vibration surface of the third vibration source 16 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the second vibration source 14.

[0063] Furthermore, as shown in Figure 9, a fourth vibration source 17 is provided, which is located inside the ear insertion part 11 and has vibration characteristics V4 in which the amplitude Amplitude (mm) of the input audio signal in the frequency band shows a peak at a predetermined fourth frequency f4 (Hz) that is higher than the third frequency f3 (Hz), and can vibrate independently of the first vibration source 13, the second vibration source 14, and the third vibration source 16. Here, the second vibration source 14 is on the higher frequency side than the first vibration source 13, the third vibration source 16 is on the higher frequency side than the second vibration source 14, and the fourth vibration source 17 is on the higher frequency side than the third vibration source 16. Therefore, in the present invention, the vibration sources on the higher frequency side of the four vibration sources are arranged sequentially so as to be closer to the cartilage.

[0064] As a result, when the first vibration source 13, the second vibration source 14, the third vibration source 16, and the fourth vibration source 17 vibrate simultaneously, the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, the vibration characteristics V3 of the third vibration source 16, and the vibration characteristics V4 of the fourth vibration source 17 overlap with each other to form a composite wave, and as a whole, a vibration characteristic V1234 with an even wider frequency band is formed. This makes it possible to further broaden the reproducible frequency band and improve sound quality.

[0065] Here, the fourth vibration source 17 vibrates independently of the first vibration source 13, the second vibration source 14, and the third vibration source 16, and the high-frequency vibration sources are arranged sequentially to approach the cartilage. As long as this configuration is not particularly limited, a wide variety of configurations and arrangements can be realized. For example, the fourth vibration source 17 can be arranged in a wide variety of positions relative to the first vibration source 13, the second vibration source 14, and the third vibration source 16, as described above. For example, the vibration surface of the fourth vibration source 17 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the first vibration source 13, and this inclination angle α is set within the range of 0 to 180 degrees, as described above. Similarly, the vibration surface of the fourth vibration source 17 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the second vibration source 14. Alternatively, the vibration surface of the fourth vibration source 17 may be configured to be inclined with respect to the vibration surface of the third vibration source 16 at a predetermined inclination angle α (degrees).

[0066] Furthermore, although the above description explained the case where a third vibration source 16 and a fourth vibration source 17 are added, the same applies even when the number of vibration sources is further increased.

[0067] Incidentally, the bone conduction earphone 1 according to the embodiment of the present invention may further include clay 20, as shown in Figure 10. The clay 20 can be attached to the outer surface of the ear insertion portion 11, is composed of biocompatible components, and is plastic.

[0068] Here, biocompatibility refers to the property of having affinity with biological tissue and not causing foreign body reactions or rejection reactions, and can be cited as the property of not causing foreign body reactions or rejection reactions even when in contact with the surface of the ear. Furthermore, plasticity refers to the property (also called plasticity) of a solid that, when deformed by force, retains its deformation (strain) even after the force is removed, and in the embodiments of the present invention, it can be cited as the property of being able to be deformed into various shapes by the user applying force.

[0069] The user attaches the clay 20 to the outer surface of the ear insertion part 11 and presses it tightly against the concha (CC), thereby deforming the clay 20 to fit the surface of the concha (CC). The vibrations from the first vibration source 13 and the second vibration source 14 are then independently transmitted to the user's external auditory canal (EC) and surrounding cartilage (Ca) via the clay 20. This improves the user's comfort of wearing the device in their ear, as well as enhances volume and sound insulation.

[0070] There are no particular limitations on the composition of clay 20, but examples of biocompatible components include silicone, polyurethane, polyethylene, tetrafluoroethylene, polyamino acid esters, polydimethylsiloxane, polylactic acid, polyglycolic acid, and poly(hydroxyethyl methacrylate). Furthermore, since clay 20 only needs to be plastic, it may also be a soft elastomer or a soft curable resin.

[0071] Furthermore, the bone conduction earphone 1 according to the embodiment of the present invention may also include a C-shaped neckband 30, as shown in Figure 11. This makes it possible to improve wearability for the user. The vibration control unit 15 at the tip of the neckband 30 may also be electrically connected to the first vibration source 13 and the second vibration source 14 via an electric wire 31. The sound collection unit 10 is a microphone unit that collects external sounds and transmits an audio signal corresponding to the collected sounds. As with the neckband 30, a pair of left and right sound collection units 10 and a vibration control unit 15 may be provided on the left and right sides of the user, corresponding to the user's left and right ears, and a pair of left and right first vibration sources 13, a second vibration source 14, and clay 20 may be placed on the user's left and right ears. As a result, each first vibration source 13 and the second vibration source 14 generates vibrations corresponding to the sound from their respective sound collection units 10, making it possible to transmit sound independently to each of the user's left and right ears, and allowing the user to experience a sense of sound direction indicating the direction from which the sound is being generated.

[0072] Furthermore, as shown in Figure 12A, the bone conduction earphone 1 according to an embodiment of the present invention may be configured in an O-shape and may include a pendant band 32 with a sound collection unit 10 and a vibration control unit 15 built into the center. In this case, a pair of left and right first vibration sources 13, a second vibration source 14, and clay 20 are provided, and the pair of left and right first vibration sources 13 and second vibration sources 14 generate vibrations in common from the sound collected by the sound collection unit 10 in the center of the pendant band 32, making it possible to transmit a common sound to the left and right ears of the user, and to accurately transmit sound to the user.

[0073] Furthermore, in the embodiment of the present invention, as shown in Figure 12B, the bone conduction earphone 1 may be configured such that the sound collection unit 10 and the ear insertion unit 11 are separated, a wireless transmission unit 16 is provided in the sound collection unit 10, and a signal receiving unit 12 is provided in the ear insertion unit 11, and the sound collection unit 10 wirelessly transmits an audio signal using the wireless transmission unit 16, and the vibration control unit 15 wirelessly receives the audio signal using the signal receiving unit 12, converts it into an electrical signal and transmits it to the first vibration source 13 and the second vibration source 14. This eliminates the possibility of cords such as wires getting caught on the user, and improves the user's wearing comfort and operability.

[0074] Furthermore, the bone conduction earphone 1 according to the embodiment of the present invention may further include a ring-shaped outer frame 21 that can be attached to the outer circumference of the ear insertion part 11, as shown in Figure 13. The outer frame 21 is not particularly limited as long as it is ring-shaped, and may be C-shaped or O-shaped. Also, the outer frame 21 may be elliptical in shape that can be attached to the concha or tragus, or it may be in a shape that is sandwiched between the tragus and antitragus. By attaching the outer frame 21 to the outer circumference of the ear insertion part 11, the clay 20 can be guided along the outer frame 21 and made to adhere closely to the inner surface of the user's ear, OES and ECS. In addition, the outer frame 21 catches on the user's concha or tragus, making it possible to more firmly adhere the first vibration source 13, the second vibration source 14, the clay 13 and the user's ear, and making it possible to firmly transmit the vibrations of the first vibration source 13 and the second vibration source 14 to the cartilage. Here, there are no particular limitations on the composition of the outer frame portion 19, but for example, a resin composed of components corresponding to the components of the clay 20 can be mentioned. Also, there are no particular limitations on the wire diameter (thickness) of the outer frame portion 21, but for example, a wire diameter in the range of 1.0 mm to 5.0 mm can be mentioned, such as an O-ring.

[0075] Examples and comparative examples of the present invention will be described below in detail, but the application of the present invention is not limited to these examples.

[0076] In the field of acoustics, it was confirmed that staggered synchronization occurs and the frequency band is broadened by simultaneously vibrating two vibration sources with different frequency bands. First, as shown in Figure 14, two vibration sources 13 and 14 were prepared, and vibration control units 15 were connected to each of the two vibration sources 13 and 14, and the respective frequency bands of the two vibration sources 13 and 14 were set. Specifically, for the first vibration source 13, the vibration control unit 15 connected to the first vibration source 13 was adjusted so that the first peak f1 was on the low frequency side, and for the second vibration source 14, the vibration control unit 15 connected to the second vibration source 14 was adjusted so that the second peak f2 was on the high frequency side. Next, an oscilloscope 100 was connected to each of the vibration control units 15 of the two vibration sources 13 and 14, and the amplitudes of the two vibration sources 13 and 14 were adjusted while checking them with the oscilloscope 100. In addition, the two vibration sources 13 and 14 were synchronized while visually checking the oscilloscope 100. In other words, a bone conduction earphone 1, which virtually includes a first vibration source 13, a second vibration source 14, and a vibration control unit 15, was created as Example 1.

[0077] Next, a measuring device 101 capable of recording sound was set up at a predetermined distance from the two vibration sources 13 and 14. The amplitudes of the two vibration sources 13 and 14 were adjusted, causing the first vibration source 13 and the second vibration source 14 to vibrate and oscillate simultaneously, and the sound was measured by the measuring device 101. The sound received by the measuring device 101 was then analyzed to calculate the output sound amplitude for the simultaneous vibration of the first vibration source 13 and the second vibration source 14.

[0078] Figure 11 is a graph showing an example of the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, the theoretically combined theoretical vibration characteristics V12t, and the experimental vibration characteristics V12e obtained by analysis. Note that the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, the theoretical vibration characteristics V12t, and the experimental vibration characteristics V12e are shown as graphs of gain against frequency. However, since gain essentially represents vibration, and the units of gain differ between the theoretical vibration characteristics V12t and the experimental vibration characteristics V12e, the gains of the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, and the theoretical vibration characteristics V12t are shown on the left axis of the graph, and the gain of the experimental vibration characteristics V12e is shown on the right axis. The gain of the experimental vibration characteristics V12e was plotted for each frequency, and an approximation curve was drawn. As shown in Figure 15, the curve of the experimental vibration characteristic V12e was in close agreement with the curve of the theoretical vibration characteristic V12t. This confirmed the occurrence of staggered tuning and the expansion of the frequency band.

[0079] Example 1 describes the effect on air vibration, but it is presumed that similar effects would also occur with vibrations in the concha (CC) or external auditory canal (EC). In this way, by simultaneously vibrating two vibration sources with different frequency bands, it will be possible to accurately reproduce any sound in any frequency band and improve sound quality.

[0080] As described above, the bone conduction earphones and method of using bone conduction earphones according to the present invention are useful not only for general bone conduction earphones but also in the field of bone conduction earphones for the hearing impaired and hard of hearing, and are effective bone conduction earphones and methods of using bone conduction earphones that enable accurate hearing of sounds in any frequency band and improve sound quality.

[0081] 1 Bone conduction earphone 10 Sound collection unit 11 Ear insertion unit 12 Signal receiving unit 13 First vibration source 14 Second vibration source 15 Vibration control unit

Claims

1. A bone conduction earphone having at least two vibration sources, comprising: a sound collection unit that collects external sound and converts it into an input audio signal corresponding to the external sound; an ear insertion unit having a size that can be inserted into the recess of the user's concha; a signal receiving unit provided inside the ear insertion unit and receiving the converted input audio signal; a first vibration source provided inside the ear insertion unit and having vibration characteristics in which the amplitude of an input audio signal in a predetermined frequency band peaks at a predetermined first frequency; a second vibration source provided inside the ear insertion unit so as to be closer to the cartilage surrounding the concha than the first vibration source when the ear insertion unit is pressed against the concha, and having vibration characteristics in which the amplitude of an input audio signal in the frequency band peaks at a predetermined second frequency higher than the first frequency, and capable of vibrating independently of the first vibration source; and a vibration control unit that simultaneously inputs the received input audio signal to the first vibration source and the second vibration source. A bone conduction earphone comprising inserting one end of the ear insertion portion into a recess in the user's concha, pressing the ear insertion portion against the concha between the user's tragus and antitragus, and simultaneously vibrating the first vibration source and the second vibration source in response to external sound, thereby independently transmitting the vibrations of the first vibration source and the second vibration source to the user's external auditory canal and surrounding cartilage.

2. The bone conduction earphone according to claim 1, wherein the maximum amplitude of the second vibration source is designed to be greater than or equal to the maximum amplitude of the first vibration source.

3. The bone conduction earphone according to claim 1, further comprising a clay that is attachable to the outer surface of the ear insertion part, is composed of biocompatible components and is plastic, wherein by attaching the clay to the outer surface of the ear insertion part and making it tightly adhere to the concha, the clay is deformed into a shape that conforms to the surface of the concha, thereby independently transmitting the vibrations of the first vibration source and the second vibration source to the user's external auditory canal and surrounding cartilage.

4. The bone conduction earphone according to claim 1, further comprising a C-shaped neckband, wherein a vibration control unit at the tip of the neckband is electrically connected to the first vibration source and the second vibration source via an electric wire, a pair of sound collecting units are installed on the left and right sides of the user corresponding to the user's left and right ears, and a pair of the first vibration source and the second vibration source are installed on the user's left and right ears.

5. The bone conduction earphone according to claim 1, wherein the sound collection unit and the ear insertion unit are separated, a wireless transmitter is provided in the sound collection unit, a signal receiving unit is provided in the ear insertion unit, the sound collection unit wirelessly transmits an audio signal using the wireless transmitter, and the vibration control unit wirelessly receives the audio signal using the signal receiving unit, converts it into an electrical signal, and transmits it to the first vibration source and the second vibration source.

6. The bone conduction earphone according to claim 1, further comprising a pendant band configured in the shape of the letter O, with the sound collection unit and the vibration control unit built into the central part.

7. The bone conduction earphone according to claim 1, further comprising a ring-shaped outer frame portion to which the outer periphery of the ear insertion portion can be attached.

8. A bone conduction earphone having at least two vibration sources, comprising: a sound collection unit that collects external sound and converts it into an input audio signal corresponding to the external sound; an ear insertion unit having a size that can be inserted into the cavity of the user's concha; a signal receiving unit provided inside the ear insertion unit and receiving the converted input audio signal; a first vibration source provided inside the ear insertion unit and having vibration characteristics in which the amplitude of an input audio signal in a predetermined frequency band shows a peak at a predetermined first frequency; a second vibration source provided inside the ear insertion unit so as to be closer to the cartilage surrounding the concha than the first vibration source when the ear insertion unit is pressed against the concha, and having vibration characteristics in which the amplitude of an input audio signal in the frequency band shows a peak at a predetermined second frequency higher than the first frequency, and capable of vibrating independently of the first vibration source; and a vibration control unit that simultaneously inputs the received input audio signal to the first vibration source and the second vibration source, the method of using the bone conduction earphone, A method for using bone conduction earphones, comprising: a pressing step of inserting one end of the ear insertion part into a recess in the user's concha cavity and pressing the ear insertion part against the concha cavity between the user's tragus and antitragus; and a vibration step of simultaneously vibrating the first vibration source and the second vibration source based on the external sound, and independently transmitting the vibration of the first vibration source and the vibration of the second vibration source to the user's external auditory canal and surrounding cartilage.

9. A method for using a bone conduction earphone according to claim 8, wherein a plastic clay composed of biocompatible components is attached to the outer surface of the ear insertion part and made to adhere closely to the concha cavity, thereby deforming the clay into a shape that conforms to the surface of the concha cavity, and independently transmitting the vibrations of the first vibration source and the second vibration source to the user's external auditory canal and surrounding cartilage.

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