Device for reducing sound leakage of bone conduction product and application

Abstract

The invention discloses a bone conduction product sound leakage reducing device and application, and belongs to the technical field of bone conduction, the bone conduction product sound leakage reducing device comprises a structural body attached to human tissue, and the structural body attached to the human tissue comprises a structural part directly attached to the human tissue and a structural part which is not attached to the human tissue and is in direct contact with air; the structural member attached to the human tissue can be directly connected with the structural member which is not attached to the human tissue and is in direct contact with the air, or can be connected by arranging a middle connecting structural member between the two structural members; a plurality of middle connecting structural parts are arranged, and the middle connecting structural parts refer to connecting structural parts directly connected with structural parts directly attached to human tissue or structural parts which are not attached to the human tissue and are in direct contact with air. According to the invention, the conduction efficiency of vibration to human tissues is greatly improved, and meanwhile, the radiation of vibration to air is reduced, so that sound leakage is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of bone conduction, and particularly relates to a device and application for reducing sound leakage of bone conduction products. Background Art

[0002] Bone conduction headphones, bone conduction glasses, bone conduction hearing aids, bone-9 conduction for sleep aid, or bone conduction neuromodulation and other bone conduction products are increasingly accepted by the public due to the unique sound conduction characteristics of bone conduction.

[0003] Bone conduction headphones convert sound into mechanical vibrations and utilize the skull, bony labyrinth, endolymph, cochlea, auditory center, etc. to transmit sound waves, reducing the number of sound wave transmission steps, increasing transmission clarity, and reducing sound wave diffusion, providing users with a unique auditory experience. Wearing bone conduction headphones is healthy and comfortable, that is, there is no need to insert them into the ear canal, avoiding damage to the eardrum, reducing ear discomfort and hearing damage caused by long-term wearing of headphones, and keeping the ear canal fresh. Moreover, it is safe and convenient: when worn, it does not block the ear canal, and in scenarios such as sports, the surrounding environmental sounds can be noticed at any time, ensuring safety during use.

[0004] Bone conduction glasses are similar to bone conduction headphones. They also utilize bone conduction technology to convert sound into vibration signals and transmit them to the inner ear through the wearer's skull, thereby realizing sound perception. It combines bone conduction technology with glasses, integrating audio-visual functions, without the need to wear additional headphones, which is convenient for carrying and using, especially suitable for use during outdoor activities or sports.

[0005] Bone conduction hearing aids transmit sound to the inner ear through bone conduction technology to help patients with hearing impairments improve their hearing. For some patients with conductive hearing loss caused by external auditory canal atresia, otitis media, etc., bone conduction hearing aids are an effective hearing aid device. It can bypass the diseased parts of the external auditory canal and middle ear and directly transmit sound vibrations to the inner ear, thereby improving hearing.

[0006] Bone conduction sleep aid and neuromodulation products transmit electrical signals to the brain through bone conduction technology for the treatment of insomnia or certain neurological diseases, such as Parkinson's disease, epilepsy, etc. It stimulates specific regions of the brain to regulate the function of the nervous system, thereby relieving insomnia or symptoms of certain neurological diseases.

[0007] The types of bone conduction include two methods: hard bone conduction and cartilage conduction. There is also a bone-air hybrid conduction combined with air conduction. If the position where the bone conduction product is attached to the human head skin is the hard bone of the human skull, it belongs to hard bone conduction. If the attachment position is the cartilage on the auricle or around the tragus, then it belongs to cartilage conduction. Generally, cartilage conduction also has air-conducted sounds, so it also belongs to a type of bone-air combined hybrid conduction.

[0008] One prominent advantage of bone conduction products and air conduction products is that their sound leakage is relatively small, but sound leakage cannot be completely eliminated. Why does a bone conduction headphone transmit sound with sound leakage? Because the oscillator drives the outer shell of the headphone to vibrate as well. The sound of a bone conduction headphone is transmitted through the vibration of bones. Therefore, when working, the outer shell of the bone conduction headphone vibrates with the sound vibration, and the vibrating sound is also emitted as the outer shell of the bone conduction headphone vibrates. This causes the outer shell of the bone conduction headphone to act like an "amplifying horn", spreading the sound in all directions. Therefore, due to its structural limitations, the leakage of its sound is inevitable.

[0009] However, due to privacy and confidentiality reasons, the average wearer does not want sound leakage to occur. Additionally, for bone conduction hearing aids, to achieve a relatively good hearing aid effect, the sound of the bone conduction oscillator needs to be amplified by dozens of dB. At this time, if the sound leakage is large, it will cause the leaked sound to enter the microphone in the headphone, resulting in howling. Also, for the scenario where the bone conduction oscillator is used for sleep aid, it is even more desirable that the bone conduction does not produce excessive sound leakage, so as not to affect people resting nearby. For the above reasons, further reducing and controlling sound leakage is an urgent issue.

[0010] Searching domestic patents, entering "suppress sound leakage & bone conduction oscillator" can retrieve 8 patents. Entering "suppress sound leakage & bone conduction speaker" can retrieve 36 patents. Among them, the more typical one is the sound leakage reduction design of AfterShokz Technologies Ltd. (and its subsidiary Voxtech). The patent ideas for reducing sound leakage through sound guiding holes, represented by "Chinese Patent Publication No. CN106470371B - A bone conduction speaker capable of suppressing sound leakage" and "Chinese Patent Publication No. CN103716739B - A method for suppressing sound leakage of a bone conduction speaker and a bone conduction speaker", etc., account for 8 search items. Additionally, there are patents such as the bone conduction glasses of Oppo "CN109121038A - A wearable device for suppressing sound leakage, a method for suppressing sound leakage, and a storage medium".

[0011] The bone conduction speakers capable of suppressing sound leakage designed in Chinese Patent Publication Nos. CN106470371B and CN103716739B include an open-shaped outer shell, a vibration panel, and a transducer device, where: the transducer device is used to generate vibrations and is accommodated inside the outer shell; the vibration panel is used to fit against the skin and transmit vibrations; at least one sound guiding hole is opened on at least a part of the outer shell, and the sound guiding hole is used to lead the in-shell sound wave formed by the vibration of the air inside the outer shell to the outside of the outer shell, and interfere with the leaked sound wave formed by the outer shell vibrating to push the air outside the shell, so as to reduce the amplitude of the leaked sound wave. This invention utilizes the principle of sound wave interference to reduce the amplitude, thereby achieving the effect of reducing sound leakage.

[0012] A wearable glasses designed according to Chinese Patent Publication No. CN109121038A for suppressing sound leakage includes: a first bone conduction speaker and a second bone conduction speaker; the first bone conduction speaker is used to generate a first mechanical vibration with the same frequency and amplitude as the sound signal, wherein the first mechanical vibration drives the air to vibrate, forming a sound leakage sound wave propagating in the air; the second bone conduction speaker is used to generate a second mechanical vibration with a phase difference of a preset angle from the first mechanical vibration, wherein the second mechanical vibration drives the air to vibrate, forming a suppression sound wave propagating in the air, and the sound leakage is suppressed by the interference between the suppression sound wave and the sound leakage sound wave. By adopting the above technical solution, the sound leakage sound wave and the suppression sound wave can interfere with each other after propagating a certain distance to weaken the amplitude of the sound leakage sound wave, and the sound leakage can be effectively suppressed.

[0013] The above solution for suppressing sound leakage not only has a complex implementation but also has a poor sound leakage suppression effect, mainly manifested in that it only suppresses sound leakage in certain frequency bands and certain directions and cannot suppress sound leakage omnidirectionally and across all frequency bands.

[0014] AfterShokz designs sound guiding holes on the oscillator and the earphone housing to lead the in-shell sound wave formed by the vibration of the air inside the housing to the outside of the housing, and interfere with the sound leakage sound wave formed by the vibration of the housing pushing the air outside the housing to reduce the amplitude of the sound leakage sound wave. This method requires drilling holes in the housing. Drilling the holes themselves is not complex, but the side effects of the holes make the subsequent design complex. For example, one of the greatest advantages of bone conduction is waterproof and sweatproof. After drilling holes in the housing, very complex waterproof and sweatproof designs are required. In addition, this method of using the sound wave interference principle by opening sound guiding holes to weaken the amplitude of the sound leakage sound wave to suppress sound leakage is essentially a dipole method, with two sound wave sources. One is the sound wave generated by the vibration of the housing, and the other is the sound wave generated by the sound guiding hole. The interference of the two sound waves has directionality. That is to say, in one direction, the sound wave interference cancels each other out, but in another direction, the sound wave interference is superimposed and enhanced. In the direction where the sound wave is superimposed and enhanced, the sound leakage is even greater. Moreover, even in the direction where the sound wave interference cancels each other out, for different sound wave frequency bands, the cancellation effect varies greatly, which is related to the distance between the two sound wave sources. Once the headphone structure design is fixed, the distance between the two sound wave sources is fixed. Therefore, the sound wave interference cancellation is only effective for sound waves in a part of the frequency bands. Generally speaking, suppressing sound leakage by sound wave interference has frequency band limitations and direction limitations:

[0015] Frequency band limitations:

[0016] Low - frequency band: Low - frequency sounds have longer wavelengths and stronger diffraction ability during propagation, and are not easily blocked or interfered with. When the reverse sound waves generated by bone conduction headphones interfere with the leaking sound waves in the low - frequency band, it is difficult to completely cancel them, resulting in relatively poor low - frequency leaking sound suppression effect. For example, when listening to music with a lot of bass, even with leaking sound suppression technology, obvious low - frequency "buzzing" sounds may still be heard at a certain distance.

[0017] High - frequency band: High - frequency sounds have shorter wavelengths and are prone to scattering and attenuation during propagation. When bone conduction headphones generate reverse sound waves in the high - frequency band, due to factors such as the frequency response characteristics of the headphones themselves and the performance of the oscillators, the high - frequency components of the reverse sound waves may be insufficient or the interference effect with the high - frequency part of the leaking sound waves is not ideal, making the high - frequency leaking sound suppression unstable, and the leaking sound may increase at certain high - frequency points.

[0018] Directivity limitation:

[0019] Horizontal direction: In the horizontal direction, although sound wave interference can make the sound propagate more concentratedly towards the wearer's ear direction, reducing side leakage, when the angle between the sound propagation direction and the headphone axis is large, the interference effect will weaken, and the leaking sound suppression effect will decrease accordingly. For example, when the wearer turns their head to one side, the leakage on the other side may be relatively obvious.

[0020] Vertical direction: Due to the shape and structure of the human head and ears, and the propagation characteristics of sound in the vertical direction, the leaking sound suppression effect of bone conduction headphones in the vertical direction is relatively poor. When the wearer lowers or raises their head, the sealing between the headphone and the ear changes, which will affect the sound wave interference effect, resulting in increased leakage above or below.

[0021] If there are multiple sound - guiding holes, the sound wave interference between these multiple sound wave sources becomes more complex. The above - mentioned frequency band limitations and directivity limitations will increase rapidly with the complexity, and the actual leaking sound suppression effect is uncontrollable, so the practicality is poor.

[0022] The patent with Chinese Patent Publication No. CN109121038A suppresses noise through sound wave interference generated by the sound waves respectively produced by the first bone conduction speaker and the second bone conduction speaker. The inherent frequency band limitations and directivity limitations of the above - mentioned sound wave interference still exist. Moreover, the two bone conduction oscillators are on the same structural component, not to mention that the structural design becomes complex, and how to avoid crosstalk between the two bone conduction oscillators poses a huge challenge to the structural design and related algorithm design. Summary of the Invention

[0023] The embodiments of the present invention provide a device and application for reducing the leaking sound of bone conduction products to solve the problems in the prior art.

[0024] The embodiments of the present invention adopt the following technical solutions: A device for reducing sound leakage of a bone conduction product, including a structure attached to human tissue, where the structure attached to human tissue includes a structural member directly attached to human tissue and a structural member not attached to human tissue and directly in contact with air; the structural member attached to human tissue and the structural member not attached to human tissue and directly in contact with air can be directly connected, or can be connected by arranging an intermediate connecting structural member therebetween; if there are multiple intermediate connecting structural members, then the intermediate connecting structural member refers to a connecting structural member directly connected to the structural member directly attached to human tissue or to the structural member not attached to human tissue and directly in contact with air.

[0025] Further, the structure attached to human tissue consists of two parts: a structural member directly attached to human tissue and a structural member not attached to human tissue and directly in contact with air;

[0026] Or it consists of three structural members: a structural member directly attached to human tissue, a structural member not attached to human tissue and directly in contact with air, and a connecting member connecting the two structural members of the structural member attached to human tissue and the structural member not attached to human tissue and directly in contact with air; or it consists of more structural members: such as a structural member directly attached to human tissue, a structural member not attached to human tissue and directly in contact with air, a connecting member connecting the two structural members of the structural member attached to human tissue and the structural member not attached to human tissue and directly in contact with air, and other supporting structural members.

[0027] Further, the acoustic impedance of the structural member attached to human tissue satisfies the material of [0.089, 88.28]*10 6 Rayleigh (kg / m 2 ·s); the acoustic impedance of the structural member not attached to human tissue and directly in contact with air satisfies the material of [0.05, ∞)*10 6 Rayleigh (kg / m 2 ·s).

[0028] Further, the part of the structural member attached to human tissue that contacts human tissue is one of cartilage, hard bone, muscle, and fat;

[0029] If the contact part is cartilage, the acoustic impedance of the structural member at the cartilage-attached part is [0.10, 25.20]*10 6 Rayleigh (kg / m 2 ·s); if the contact part is hard bone such as the skull, the acoustic impedance of the structural member at the hard bone-attached part is [0.35, 88.28]*10 6 Rayleigh (kg / m 2 ·s);

[0030] If the contact part is muscle, the acoustic impedance of the structural member at the muscle-attached part is [0.104, 26.12]*106 Rayleigh (kg / m 2 ·s) material;

[0031] If the contact part is fat, the acoustic impedance of the structural member attached to the fat part is [0.089, 22.35]*10 6 Rayleigh (kg / m 2 ·s) material.

[0032] Furthermore, the human tissues contacted by the structure attached to the human tissue include human skin tissue, human muscle tissue, and human bone tissue.

[0033] Furthermore, the bone conduction oscillator and the structural member attached to the human tissue are directly or indirectly connected and fixed, and the vibration energy of the bone conduction oscillator is transmitted to the human skin, muscle, and bone through the structural member attached to the human tissue; the bone conduction oscillator can be directly connected to the structural member attached to the human tissue, or the bone conduction oscillator can be fixed on the oscillator bracket, and the oscillator bracket is connected to the structural member attached to the human tissue.

[0034] Furthermore, the oscillator fixing bracket for fixing the bone conduction oscillator is connected to the structural member attached to the human tissue. Assuming that the acoustic impedance of the oscillator fixing bracket is Z1 and the acoustic impedance of the human tissue during wearing is Z2, then when selecting the material of the structural member attached to the human tissue, its acoustic impedance Z preferably satisfies the following formula, and at this time the attenuation of the acoustic wave energy transmitted to the human tissue is relatively small, thereby increasing the amplitude of the acoustic wave transmitted into the human body;

[0035]

[0036] Furthermore, an intermediate vibration isolation layer is preferably designed between the structural member attached to the human tissue and the structural member that is not attached to the human tissue and is in direct contact with the air; assuming that the acoustic impedance of the structural member attached to the human tissue is Z1 and the acoustic impedance of the structural member that is not attached to the human tissue and is in direct contact with the air is Z2, then the acoustic impedance Z of the intermediate vibration isolation layer is preferably to satisfy the following formula, and at this time the attenuation of the acoustic wave energy transmitted from the structural member attached to the human tissue through the intermediate vibration isolation layer to the structural member that is not attached to the human tissue and is in direct contact with the air will be relatively large, and at this time the leakage of the acoustic wave radiated into the air through the structural member in contact with the air can be further reduced;

[0037] Or

[0038] Furthermore, the direct connection between the structural component in contact with the human tissue and the structural component not in contact with the human tissue and directly exposed to air can be achieved by bonding, riveting, tenon-mortise joint, reverse buckle, etc.; if there is an intermediate structural component, the connection between the intermediate structural component and the other two can also be by bonding, riveting, tenon-mortise joint, reverse buckle, etc. If the vibrator is connected to the structural component in contact with the human tissue through a vibrator fixing bracket, the connection between the two can also be by bonding, riveting, tenon-mortise joint, reverse buckle, etc.;

[0039] An application of reducing sound leakage in a bone conduction product, the above method of reducing sound leakage is applicable to bone conduction headphones, bone conduction glasses, wired headphones, wireless headphones, AR glasses, VR glasses, eye masks, forehead wearers, smart watches, smart bracelets, head-mounted devices, wearable devices, smart phones, game pads, game headphones, game steering wheels, game pedals, mice, keyboards, touch screens, electrical control panels, touch control devices, screen sound-emitting devices, in-vehicle tactile feedback devices, smart cockpits, gaming chairs, massage chairs, massagers, tactile feedback vests, tactile feedback belts, leg guards, helmets, hats, neck massagers, hand-held massagers, tactile feedback gloves, leg massagers, tactile feedback leg devices, foot massagers, abdominal massagers or chest massagers, hearing aids, sleep aids or tactile feedback network interconnection devices, sleeping pads, pillows, sofas, massage chairs, in-vehicle backrests, in-vehicle headrests and other products.

[0040] The above at least one technical solution adopted in the embodiments of the present invention can achieve the following beneficial effects:

[0041] 1. Significantly reduce sound leakage: Through the split structure and soft connection, the path of vibration propagation outward is effectively blocked, and the sound leakage problem is greatly reduced.

[0042] 2. Improve conduction efficiency: The vibrator bracket assembly is located in the upper shell part, ensuring that the vibration energy is mainly conducted towards the human body direction, improving the bone conduction effect.

[0043] 3. Improve wearing comfort: The use of soft materials reduces local pressure and improves the comfort of long-term wearing.

[0044] 4. Extend the product life: The innovative fixing method and shock-absorbing structure effectively protect the bone conduction vibrator and extend the service life of the product.

[0045] 5. Enhance acoustic performance: The material selection with a specific sound impedance range and the application of multiple noise reduction measures significantly enhance the overall acoustic performance of the product.

[0046] 6. Strong adaptability: The design of multiple implementation methods enables the present invention to be flexibly applied to different types of bone conduction products. Description of the Drawings

[0047] The accompanying drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the drawings:

[0048] Figure 1 is a schematic diagram of acoustic transmission through the interface between two media in the present invention;

[0049] Figure 2 is a schematic diagram of acoustic transmission through two interfaces between three media in the present invention;

[0050] Figure 3 is a three-dimensional structural schematic diagram of the integrated molding of the oscillator bracket and the human body-attached structure member in the present invention;

[0051] Figure 4 is a split three-dimensional structural diagram of the integrated molding of the oscillator bracket and the human body-attached structure member in the present invention;

[0052] Figure 5 is a three-dimensional structural schematic diagram of the separation of the oscillator bracket and the human body-attached structure member in the present invention;

[0053] Figure 6 is a split three-dimensional structural diagram of the separation of the oscillator bracket and the human body-attached structure member in the present invention;

[0054] Figure 7 is a three-dimensional structural schematic diagram of the vibration isolation layer between the human body-attached structure member and the air-contact structure member in the present invention;

[0055] Figure 8 is a split three-dimensional structural diagram of the vibration isolation layer between the human body-attached structure member and the air-contact structure member in the present invention;

[0056] Figure 9 is a functional relationship diagram of the energy transmission coefficient and the ratio of acoustic impedance in the present invention;

[0057] Figure 10 is a schematic diagram written in the dB domain, with the abscissa being 20log(η) and the ordinate being 20log(T);

[0058] Figure 11 is the functional relationship of the change of the acoustic wave transmission efficiency with the acoustic impedance of the intermediate vibration isolation structure in Example 4-1 of the present invention Figure 1 ;

[0059] Figure 12 is the functional relationship of the change of the acoustic wave transmission efficiency with the acoustic impedance of the intermediate vibration isolation structure in Example 4-1 of the present invention Figure 2 ;

[0060] Figure 13It is a functional relationship diagram showing the change of the acoustic wave transmission efficiency with the acoustic impedance of the skin-contact structure in Embodiment 5 of the present invention. Detailed implementation manners

[0061] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0062] The following will, with reference to the drawings, elaborate on the technical solutions provided by various embodiments of the present invention for a sound leakage reduction device and application of a bone conduction product.

[0063] Refer to Figures 1 to 13 As shown, an embodiment of the present invention provides a sound leakage reduction device for a bone conduction product, including a structure in contact with human tissues. The structure in contact with human tissues includes a structural member directly in contact with human tissues and a structural member not in contact with human tissues and directly in contact with air; the structural member directly in contact with human tissues and the structural member not in contact with human tissues and directly in contact with air can be directly connected, or can be connected by arranging an intermediate connecting structural member therebetween; if there are multiple intermediate connecting structural members, then the intermediate connecting structural member refers to a connecting structural member directly connected to the structural member directly in contact with human tissues or the structural member not in contact with human tissues and directly in contact with air.

[0064] Among them, the acoustic impedance of the structural member directly in contact with human tissues is preferably a material located in [0.089, 88.28] * 10 6 Rayleigh (kg / m 2 ·s). In this way, the attenuation of the acoustic wave passing through the human skin from the skin-contact structural member into the human body is relatively small, and the acoustic wave energy is mainly radiated into the human body; at the same time, the acoustic impedance of the structural member not in contact with human tissues and directly in contact with air is preferably a material located in [0.05, ∞) * 10 6 Rayleigh (kg / m 2 ·s). In this way, when the acoustic wave propagates from the housing material to the air, the attenuation of the acoustic wave at the interface between the housing and the air two media is relatively large, so the sound leakage is relatively small; and the acoustic impedance of the structural member in contact with human tissues is designed to be not equal to the acoustic impedance of the structural member not in contact with human tissues and directly in contact with air, and preferably the former acoustic impedance is less than the latter acoustic impedance.

[0065] Furthermore, the structure in contact with human tissues is composed of two parts: a structural member directly in contact with human tissues and a structural member not in contact with human tissues and directly in contact with air;

[0066] Or it consists of three structural components: a structural component directly attached to human tissue, a structural component not attached to human tissue but directly in contact with air, and a connecting component that connects the two aforementioned structural components; or it consists of more structural components: such as a structural component directly attached to human tissue, a structural component not attached to human tissue but directly in contact with air, a connecting component that connects the two aforementioned structural components, and other supporting structural components.

[0067] Further, the acoustic impedance of the structural component attached to human tissue satisfies [0.089, 88.28]*10 6 Rayleigh (kg / m 2 ·s); the acoustic impedance of the structural component not attached to human tissue but directly in contact with air satisfies the material of [0.05, ∞)*10 6 Rayleigh (kg / m 2 ·s).

[0068] Further, the part of the structural component attached to human tissue that contacts human tissue is one of cartilage, bone, muscle, and fat;

[0069] If the contact part is cartilage, the acoustic impedance of the structural component at the cartilage-attached part is [0.10, 25.20]*10 6 Rayleigh (kg / m 2 ·s); if the contact part is bone such as the skull, the acoustic impedance of the structural component at the bone-attached part is [0.35, 88.28]*10 6 Rayleigh (kg / m 2 ·s);

[0070] If the contact part is muscle, the acoustic impedance of the structural component at the muscle-attached part is [0.104, 26.12]*10 6 Rayleigh (kg / m 2 ·s);

[0071] If the contact part is fat, the acoustic impedance of the structural component at the fat-attached part is [0.089, 22.35]*10 6 Rayleigh (kg / m 2 ·s).

[0072] Further, the human tissue contacted by the structural body attached to human tissue includes human skin tissue, human muscle tissue, and human bone tissue. For example, the hard bone of the human skull, and the cartilage tissue of the auricle or tragus or around them, or the muscle or fat tissue of the human torso or limbs;

[0073] Furthermore, the bone conduction oscillator and the structural member in contact with the human tissue are directly or indirectly connected and fixed, and the vibration energy of the bone conduction oscillator is transmitted to the human skin, muscles and bones through the structural member in contact with the human tissue; the bone conduction oscillator can be directly connected to the structural member in contact with the human tissue, or the bone conduction oscillator can be fixed on the oscillator bracket, and the oscillator bracket is connected to the structural member in contact with the human tissue.

[0074] Furthermore, the oscillator fixing bracket for fixing the bone conduction oscillator is connected to the structural member in contact with the human tissue. Assuming that the acoustic impedance of the oscillator fixing bracket is Z1 and the acoustic impedance of the human tissue during wearing is Z2, then when selecting the material of the structural member in contact with the human tissue, its acoustic impedance Z preferably satisfies the following formula. At this time, the attenuation of the acoustic wave energy transmitted to the human tissue is relatively small, thereby increasing the amplitude of the acoustic wave transmitted into the human body;

[0075]

[0076] Furthermore, an intermediate vibration isolation layer is preferably designed between the structural member in contact with the human tissue and the structural member that is not in contact with the human tissue and is directly in contact with the air; assuming that the acoustic impedance of the structural member in contact with the human tissue is Z1 and the acoustic impedance of the structural member that is not in contact with the human tissue and is directly in contact with the air is Z2, then the acoustic impedance Z of the intermediate vibration isolation layer is preferably to satisfy the following formula. At this time, the attenuation of the acoustic wave energy transmitted from the structural member in contact with the human tissue through the intermediate vibration isolation layer to the structural member that is not in contact with the human tissue and is directly in contact with the air will be relatively large. At this time, the leakage sound of the acoustic wave radiated into the air through the structural member in contact with the air can be further reduced;

[0077] Or

[0078] Furthermore, the direct connection method between the structural member in contact with the human tissue and the structural member that is not in contact with the human tissue and is directly in contact with the air can be bonding, riveting, tenon and mortise joint, reverse buckle, etc.; if there is an intermediate structural member, the connection method between the intermediate structural member and the two can also be bonding, riveting, tenon and mortise joint, reverse buckle, etc. If the oscillator is connected to the structural member in contact with the human tissue through the oscillator fixing bracket, then the connection method between the two can also be bonding, riveting, tenon and mortise joint, reverse buckle, etc.;

[0079] An application of reducing sound leakage in bone conduction products. The above method for reducing sound leakage is applicable to bone conduction headphones, bone conduction glasses, wired headphones, wireless headphones, AR glasses, VR glasses, eye masks, forehead wearables, smart watches, smart bracelets, head-mounted devices, wearable devices, smartphones, game pads, game headphones, game steering wheels, game pedals, mice, keyboards, touch screens, electrical control panels, touch control devices, screen sound-emitting devices, in-vehicle tactile feedback devices, smart cockpits, gaming chairs, massage chairs, massagers, tactile feedback vests, tactile feedback belts, leg wraps, helmets, hats, neck massagers, handheld massagers, tactile feedback gloves, leg massagers, tactile feedback leg devices, foot massagers, abdominal massagers or chest massagers, hearing aids, sleep aids or tactile feedback network interconnection devices, products such as sleeping pads, pillows, sofas, massage chairs, in-vehicle backrests, and in-vehicle headrests.

[0080] Basic theoretical derivation part of acoustic impedance:

[0081] Acoustic impedance is an important physical quantity representing the acoustic characteristics of a medium. The acoustic impedance (Z) is equal to the product of the density (ρ) and the sound speed (C) of the medium, i.e., Z = ρ×C. When the unit of P is g / cm 3 the unit of acoustic impedance is rayl.

[0082] Assume that sound waves are transmitted from one medium to another. Since the acoustic impedances of the two media are inconsistent, sound wave reflection occurs at the interface between the media, that is, part of the sound waves are reflected back, and the other part is transmitted through. The difference in the acoustic impedances of the two media is called impedance mismatch. Moreover, the greater the impedance mismatch, the greater the proportion of the energy of the sound wave reflected at the interface between the media during propagation. If the impedance matching is better, the greater the proportion of the energy of the sound wave penetrating the interface between the media.

[0083] Assume that the acoustic impedance of medium 1 is Z1 and the acoustic impedance of medium 2 is Z2. Then, during the process of sound waves propagating from medium 1 to medium 2, the amplitude-based sound wave reflection coefficient R is calculated by the following formula:

[0084]

[0085] The energy-based sound wave emission coefficient is calculated by the following formula:

[0086]

[0087] The amplitude-based sound wave transmission coefficient T is calculated by the following formula:

[0088]

[0089] It can also be seen from the above formula that the relationship between R and T is:

[0090] R + 1 = T

[0091] That is:

[0092] T - R = 1 Above, the amplitude value of R means that the reflected wave is out of phase. The transmitted wave plus the reflected wave after inversion is equal to the amplitude of the incident wave.

[0093] However, in the actual process, the amplitudes of the reflected wave and the transmitted wave do not necessarily add up to 1, because when the sound wave passes through the medium interface, the amplitude is not necessarily conserved. In contrast, because of energy conservation, the energy of the reflected wave plus the energy of the transmitted wave must be equal to the energy value of the incident wave. Based on this principle, the energy transmission coefficient can be simply calculated as follows:

[0094]

[0095] Let

[0096]

[0097] The functional relationship between the energy transmission coefficient and the acoustic impedance ratio can be obtained as follows. The abscissa is η and the ordinate is T:

[0098] Written in the dB domain, the abscissa is 20log(η) and the ordinate is 20log(T), so there is:

[0099] Example 1: Calculate the preferred range of the acoustic impedance of the structural member attached to the human tissue

[0100] For the structural member in the bone conduction product that is in direct contact with the human tissue, in order to increase the radiation of the sound wave to the human tissue, the curved surface (which can be a complex curved surface) of the structural member in contact with the human tissue that contacts the human tissue should transmit the sound wave energy into the human tissue as much as possible to form a sound wave. Therefore, for the interface formed by the direct contact between the structural member in contact with the human tissue and the human tissue, it is required that the transmission efficiency of the sound wave energy transmission is as high as possible;

[0101] Let's simply calculate that for the requirement of the acoustic impedance of the structural member in contact with the human tissue, the more the sound wave can be transmitted into the human tissue, the better.

[0102] The acoustic impedance of normal human tissue

[0103] Tissue and organ <![CDATA[Density (g / cm 3 )]]> Sound velocity (m / s) <![CDATA[Acoustic impedance (×10 5 Rayleigh (g / cm 2 ·s))]]> Brain 1.038 1540 1.588 Cerebellum 1.030 1470 1.514 Fat 0.955 1476 1.410 Soft tissue 1.016 1500 1.590 Muscle 1.074 1568 1.648 Liver 1.050 1570 1.648 Skull 1.658 3360 5.570 Fetal body 1.023 1505 1.579

[0104] Assume that the acoustic impedance of the structural member in contact with the human body is Z contact , and the acoustic impedance of the part of the bone conduction product in contact with the human tissue is Z tissue , Let Since it is required that the energy transmission of sound waves through the interface between the auricle and air be as low as possible, that is, the transmission efficiency of the energy transmission of sound waves should be as low as possible. Generally, it is desired that the energy attenuation at this interface be less than 13 dB.

[0105]

[0106] x (dB domain) η = 10^x 20 log(η) T = 4η / (η + 1)^2 20 log(T) -1.2 0.063095734 -24.0 0.22 -13.0 -1 0.1 -20.0 0.33 -9.6 -0.8 0.158489319 -16.0 0.47 -6.5 -0.6 0.251188643 -12.0 0.64 -3.9 -0.4 0.398107171 -8.0 0.81 -1.8 -0.2 0.630957344 -4.0 0.95 -0.5 0 1 0.0 1.00 0.0 0.2 1.584893192 4.0 0.95 -0.5 0.4 2.511886432 8.0 0.81 -1.8 0.6 3.981071706 12.0 0.64 -3.9 0.8 6.309573445 16.0 0.47 -6.5 1 10 20.0 0.33 -9.6 1.2 15.84893192 24.0 0.22 -13.0

[0107] As can be seen from the above table, to make the sound wave transfer from the structural member in contact with the human body to the human tissue as much as possible, the energy attenuation of the sound wave at the interface in contact with the human body should be less than 13 dB, which means that the value range of η is:

[0108] 0.063095734 < η < 15.84893192

[0109] That is:

[0110]

[0111] 0.063095734 * Z tissue <Z contact <15.84893192 * Z tissue

[0112] According to the international standard measurement units, the acoustic impedance data of soft tissue, muscle, skull, fat, etc. are given again as follows:

[0113] Tissue and organ <![CDATA[Density (kg / *m 3 )]]> Sound velocity (m / s) <![CDATA[Acoustic impedance (×10 6 Rayleigh (kg / m 2 ·s))]]> Fat 955 1476 1.410 Soft tissue 1016 1500 1.590 Muscle 1074 1568 1.648 Skull 1658 3360 5.570

[0114] a) Assume that the position of the human tissue in contact is cartilage, such as the auricle of the human body, or the tragus or the cartilage tissue around these two.

[0115] At this time, Z tissue is the acoustic impedance Z of the cartilage tissue cartilage

[0116] Z tissue =Z cartilage =1.590 × *10 6

[0117] Substituting it in, we get:

[0118] 0.063095734 * Z cartilage <Z contact <15.84893192 * Z tissue

[0119] 0.063095734 * 1.590 × *10 6 <Z contact <15.84893192 * 1.590 × *106

[0120] 0.10×*10 6 <Z contact <25.20×*10 6

[0121] b) Assume that the position of the human tissue in contact is the skull, such as the mastoid behind the ear or the condyle in front of the tragus.

[0122] At this time, Z tissue is the acoustic impedance Z of the cartilage tissue skull

[0123] Z tissue = Z skull = 5.57×*10 6

[0124] Substituting gives:

[0125] 0.063095734*Z skull <Z contact <15.84893192*Z skull

[0126] 0.063095734*5.57×*10 6 <Z contact <15.84893192*5.57×*10 6

[0127] 0.35×*10 6 <Z contact <88.28×*10 6

[0128] c) Assume that the position of the human tissue in contact is human muscle, such as in the application of vibratory touch for relieving muscle pain.

[0129] At this time, Z tissue is the acoustic impedance Z of the cartilage tissue muscle

[0130] Z tissue = Z muscle = 1.648×*10 6

[0131] Substituting gives:

[0132] 0.063095734*Z muscle <Z contact <15.84893192*Z muslce

[0133] 0.063095734*1.648×*106 <Z contact < 15.84893192 * 1.648 × * 10 6

[0134] 0.104 × 10 6 <Z contact < 26.12 × * 10 6

[0135] d) Assume that the position of the human tissue in contact is human fat, such as the application of vibrotactile for local weight loss of abdominal fat.

[0136] At this time, Z tissue is the acoustic impedance Z of cartilage tissue fat

[0137] Z tissue = Z fat = 1.410 × * 10 6

[0138] Substituting gives:

[0139] 0.063095734 * Z fat <Z contact < 15.84893192 * Z fat

[0140] 0.063095734 * 1.410 × * 10 6 <Z contact < 15.84893192 * 1.410 × * 10 6

[0141] 0.089 × * 10 6 <Z contact < 22.35 × * 10 6

[0142] The acoustic impedance of the structural member in contact with human tissue in the above bone conduction product is preferably in the range of [0.089, 88.28] * 10 6 Rayleigh (kg / m 2 ·s). Materials that meet the above conditions include, for example, liquid silicone, elastic silicone, plastic materials such as PC (polycarbonate), ABS, PC + ABS, etc., TPU, PVDF (polyvinylidene fluoride), PU (polyurethane), PEEK (polyetheretherketone), soft rubber, etc.

[0143] Example 2: Calculate the preferred range of the acoustic impedance of the structural member that is not in contact with human tissue but in direct contact with air

[0144] For the structural components in bone conduction products that do not come into contact with human tissues but directly with air, in order to reduce sound leakage, the curved surface (which can be a complex curved surface) of the structural components that does not come into contact with human tissues but directly with air should minimize the transmission of sound wave energy into the air to form sound leakage. Therefore, for the interface formed by the direct contact between the structural components and air, the transmission efficiency of the sound wave energy transmission is required to be as low as possible;

[0145] Let's do a simple calculation. The requirement for the acoustic impedance of the structural components that do not come into contact with human tissues but directly with air can minimize sound leakage.

[0146] The data of the density and sound speed of air are as follows:

[0147] Medium <![CDATA[Density (kg / m 3 )]]> Sound velocity (m / s) <![CDATA[Acoustic impedance (×10 6 Rayleigh (kg / m 2 ·s))]]> Air 1.29 334 0.0004

[0148] Assume that the acoustic impedance of the curved surface material facing outward from the vibration transmission cabin housing and towards the surroundings is Z shell , let Since we want to minimize the energy transmission of sound waves through the interface between the auricle and air, that is, we require the transmission efficiency of the sound wave energy transmission to be as low as possible. Generally, it is desired that the energy attenuation at this interface is higher than 30 dB.

[0149]

[0150]

[0151]

[0152] It can be seen from the above table that to minimize sound leakage, the energy attenuation of sound waves transmitted from the structural components not in contact with the skin to the air should exceed 30 dB, which means the value range of η is:

[0153] η < 0.008035261 or η > 124.4514612

[0154] Since the auricle, as a solid material, definitely has a greater acoustic impedance than air, so only the following formula range is taken

[0155] η > 124.451461

[0156] That is:

[0157]

[0158] Z shell >124.4514612 * Z air

[0159] Substitute Zair = 0.0004 * 10 6 Rayleigh (kg / m2 Substituting (·s) gives:

[0160] Z shell >124.4514612 * 0.0004 * 10 6

[0161] Z shell >0.04978058 * 10 6

[0162] Let:

[0163] Z shell >0.05 * 10 6

[0164] For the structural member in the bone conduction product that adheres to the human tissue and is in direct contact with air without adhering to the human tissue, the acoustic impedance of the material on the curved surface facing the outside or the surroundings is desired to be in the range of [0.05, ∞] * 10 6 Rayleigh (kg / m 2 ·s). Materials that meet the above conditions include, for example, rigid plastic materials such as PC (polycarbonate), ABS, PC + ABS, acrylic, metal, ceramic, glass, wood, plastic alloy, aluminum alloy, stainless steel, titanium alloy, carbon fiber, engineering plastic and fiber composites (glass fiber reinforced plastic, carbon fiber reinforced plastic, PC + glass fiber, ABS + glass fiber, nylon + glass fiber, etc.), composite boards (PC / PMMA), etc.

[0165] Example 3: There is no intermediate connecting structural member;

[0166] The skin - adhering structural member and the structural member that does not adhere to the skin and is in contact with air are directly connected;

[0167] Example 4: There is an intermediate connecting structural member;

[0168] At this time, the skin - adhering structural member and the structural member that does not adhere to the skin and is in contact with air are connected through the intermediate connecting structural member; in the design of the earphone shell, the structural member that adheres to the human tissue is generally made to have an acoustic impedance close to that of the human tissue, so that the acoustic wave energy can be maximally transmitted into the human tissue. On the contrary, for the structural member that does not adhere to the human tissue structure, the acoustic impedance is made as high as possible. In this way, at the interface between the structural member and air, more acoustic wave energy is reflected and less is transmitted, and there is less sound leakage in the air.

[0169] Between the structural member in contact with human tissue and the structural member in contact with air, in order to reduce sound leakage, an additional vibration isolation structural member is added. Assuming that the acoustic impedance of the structural member in contact with the human body structure is Z1, the acoustic impedance of the structural member in contact with air is Z2, and the acoustic impedance of the intermediate vibration isolation structural member is Z, then the current problem is, when Z is what value, the acoustic wave energy transmitted from the structural member Z1 in contact with human tissue to the structural member Z2 in direct contact with air is the smallest.

[0170] According to the previous formula, at the interface from the structural member in contact with human tissue to the intermediate vibration isolation structural member, the energy transfer coefficient of the acoustic wave is

[0171]

[0172] At the interface between the intermediate vibration isolation structural member and the structural member in contact with air, the energy transfer coefficient of the acoustic wave is

[0173]

[0174] The total energy transfer coefficient of the acoustic wave from the structural member in contact with human tissue to the vibration isolation structural member and then to the structural member in contact with air is:

[0175]

[0176] Taking the derivative of the above formula, we can get:

[0177]

[0178] We can get:

[0179] 16Z1Z2*2*Z(Z1 + Z) 2 (Z2 + Z) 2 -16Z1Z2Z 2 *2*(Z1 + Z)(Z2 + Z)(2Z + Z1 + Z2) = 0

[0180] Z(Z1 + Z)(Z2 + Z)-Z 2 (2Z + Z1 + Z2) = 0

[0181] Z 2 + Z1Z + Z2Z + Z1Z2-(2N 2 + Z1Z + Z2Z) = 0

[0182] Z 2 = Z1Z2

[0183]

[0184] That is, When, the value of T total is the largest. At this time, there is:

[0185]

[0186] In order to minimize the acoustic wave transmission rate, the value of Z should be as far as possible from Example 4-1:

[0187]

[0188]

[0189] According to the above, assuming that the intermediate vibration isolation layer should have an acoustic wave energy attenuation of at least more than 3 db, then by looking up the table, it can be seen that the acoustic impedance of the material of the intermediate vibration isolation layer is preferably

[0190] Z < 0.97 < 10 6 Or Z > 3.684 * 10 6

[0191] That is, when

[0192] Or

[0193] The attenuation of the intermediate vibration isolation layer for acoustic wave energy > 3 db.

[0194] For example, it can be selected from the following materials:

[0195] Soft rubber: density about 900 - 1200 kg / m^3, low sound velocity, about 50 - 150 m / s, acoustic impedance about 45000 - 180000 Rayleigh.

[0196] Latex: density around 900 - 1000 kg / m^3, sound velocity about 100 - 150 m / s, acoustic impedance about 90000 - 150000 Rayleigh.

[0197] Liquid silicone: density at 1100 - 1200 kg / m^3, sound velocity about 900 - 1000 m / s, acoustic impedance about 990000 - 1200000 Rayleigh.

[0198] Example 4-2:

[0199]

[0200]

[0201] When

[0202] Or The attenuation of the intermediate vibration isolation layer for acoustic wave energy > 3 db.

[0203] Embodiment 5: Design of a structural component layer between the oscillator fixing bracket and human tissue

[0204] On the other hand, we further examine the further disassembly of the components of the structural component in contact with human tissue. Assume that the acoustic impedance of the material of the oscillator fixing bracket is Z1, and the acoustic impedance of human tissue itself is Z2. Then, in order to allow sound waves to penetrate into human tissue as much as possible, assume that a layer of material with an acoustic impedance of Z is coated on the part of the oscillator fixing bracket in contact with human tissue.

[0205] According to the above derivation, in order to allow sound waves to penetrate into human tissue as much as possible, the optimal setting of the acoustic impedance of this coated material is:

[0206]

[0207]

[0208]

[0209] That is, select a material with an acoustic impedance close to Rayleigh (kg / m 2 ·s) as the skin-contact layer coating material. Assume that the attenuation of the sound wave energy passing through the intermediate material is less than 3 dB. Then, according to the above similar derivation, one can select

[0210]

[0211] The above are only the embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A device for reducing sound leakage of a bone conduction product, characterized in that: It includes a structure that adheres to human tissue, and the structure that adheres to human tissue includes a structure that directly adheres to human tissue and a structure that is not in contact with human tissue and is directly in contact with air; the structure that adheres to human tissue and the structure that is not in contact with human tissue and is directly in contact with air can be directly connected, and can also be connected by setting an intermediate connecting structure between the two; if there are multiple intermediate connecting structures, then the intermediate connecting structure refers to a connecting structure that is directly connected to the structure that directly adheres to human tissue or the structure that is not in contact with human tissue and is directly in contact with air.

2. The device for reducing sound leakage of a bone conduction product according to claim 1, characterized in that: The structure attached to human tissue is composed of two parts: a structure directly attached to human tissue and a structure not attached to human tissue and directly in contact with air; Or it is composed of three structural parts: a structural part directly attached to human tissue, a structural part not attached to human tissue and directly in contact with air, and a connecting part connecting the structural part attached to human tissue and the structural part not attached to human tissue and directly in contact with air; Or it may be composed of more structural parts: such as structural parts directly attached to human tissue, structural parts not attached to human tissue and directly in contact with air, connecting parts connecting the structural parts attached to human tissue and the structural parts not attached to human tissue and directly in contact with air, and other supporting structural parts.

3. The device for reducing sound leakage of a bone conduction product according to claim 1, characterized in that: The acoustic impedance of the structure attached to human tissue preferably satisfies [0.089, 88.28]*10 6 Rayleigh (kg / m 2 ·s); the acoustic impedance of the structure that is not close to human tissue and directly in contact with air should preferably satisfy [0.05,∞)*10 6 Rayleigh (kg / m 2 s) materials.

4. The device for reducing sound leakage of a bone conduction product and its application according to claim 1, characterized in that: The structure that adheres to the human tissue is one of cartilage, bone, muscle and fat. If the contact part is cartilage, the acoustic impedance of the structural part close to the cartilage is preferably [0.10, 25.20]*10 6 Rayleigh (kg / m 2 ·s); if the contact part is a hard bone such as a skull, the acoustic impedance of the structural member close to the hard bone is preferably [0.35, 88.28]*10 6 Rayleigh (kg / m 2 s) materials; If the contact part is muscle, the acoustic impedance of the structure close to the muscle is preferably [0.104, 26.12]*10 6 Rayleigh (kg / m 2 s) materials; If the contact part is fat, the acoustic impedance of the structure close to the fat part is preferably [0.089, 22.35]*10 6 Rayleigh (kg / m 2 s) materials; The human tissues contacted by the structure attached to human tissues include human skin tissues, human muscle tissues and human bone tissues.

5. The device for reducing sound leakage of a bone conduction product according to claim 1, characterized in that: The bone conduction vibrator is directly or indirectly connected and fixed to a structural member that is attached to human tissue, and the vibration energy of the bone conduction vibrator is transmitted to human skin, muscles and bones through the structural member that is attached to human tissue. The bone conduction vibrator can be directly connected to the structural member that is attached to human tissue, or the bone conduction vibrator can be fixed on a vibrator bracket, and the vibrator bracket is connected to the structural member that is attached to human tissue.

6. The device for reducing sound leakage of a bone conduction product according to claim 1, characterized in that: The vibrator fixing bracket for fixing the bone conduction vibrator is connected to the structural member close to the human tissue; assuming that the acoustic impedance of the vibrator fixing bracket is Z1, and the acoustic impedance of the human tissue when worn is Z2, then when selecting the material of the structural member close to the human tissue, its acoustic impedance Z preferably satisfies the following formula, at which time the attenuation of the sound wave energy transmitted to the human tissue is relatively small, thereby increasing the amplitude of the sound wave transmitted to the human body; 7. The device for reducing sound leakage of a bone conduction product according to claim 1, characterized in that: An intermediate vibration-insulating layer is preferably designed between the structural member contacting the human tissue and the structural member not contacting the human tissue and directly contacting the air; assuming that the acoustic impedance of the structural member contacting the human tissue is Z1, and the acoustic impedance of the structural member not contacting the human tissue and directly contacting the air is Z2, then the acoustic impedance Z of the intermediate vibration-insulating layer preferably satisfies the following formula, at which time the attenuation of the acoustic wave energy from the structural member contacting the human tissue through the intermediate vibration-insulating layer to the structural member not contacting the human tissue and directly contacting the air will be relatively large, and at this time, the sound leakage radiated to the air through the structural member contacting the air can be further reduced; or 8. The device for reducing sound leakage of a bone conduction product according to claim 1, characterized in that: The direct connection method between the structural parts that are close to human tissue and the structural parts that are not close to human tissue and are in direct contact with the air can be bonding, riveting, mortise and tenon joints, inverted buckles, etc.; if there is an intermediate structural part, the connection method between the intermediate structural part and the two can also be bonding, riveting, mortise and tenon joints, inverted buckles, etc.; the vibrator is connected to the structural part that is close to human tissue through a vibrator fixing bracket, so the connection method between the two can also be bonding, riveting, mortise and tenon joints, inverted buckles, etc.

9. Application of the device for reducing sound leakage in bone conduction products according to any one of claims 1 to 8, characterized in that: The above-mentioned device for reducing leakage sound is suitable for bone conduction headphones, bone conduction glasses, wired headphones, wireless headphones, AR glasses, VR glasses, eye masks, forehead wearers, smart watches, smart bracelets, head-mounted devices, wearable devices, smart phones, game controllers, gaming headphones, gaming steering wheels, gaming pedals, mice, keyboards, touch screens, electrical control panels, touch devices, screen sound devices, vehicle-mounted tactile feedback devices, smart cockpits, gaming chairs, massage chairs, massagers, tactile feedback vests, tactile feedback belts, leggings, helmets, hats, neck massagers, handheld massagers, tactile feedback gloves, leg massagers, tactile feedback leg devices, foot massagers, abdominal massagers or chest massagers, hearing aids, sleep aids or tactile feedback network interconnection devices, sleeping mats, pillows, sofas, massage chairs, vehicle backrests, vehicle pillows and other products.

Images