CN107334577B

CN107334577B - Silencing earphone for nuclear magnetic resonance examination

Info

Publication number: CN107334577B
Application number: CN201610939060.9A
Authority: CN
Inventors: 赵宁
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-10-31
Filing date: 2016-10-31
Publication date: 2023-07-04
Anticipated expiration: 2036-10-31
Also published as: CN107334577A

Abstract

A silencing earphone for nuclear magnetic resonance examination, its characterized in that, it includes two earplug that can be used to pack into human auditory canal and be used for accomodating the earplug box be equipped with spiral device in the earplug box, the earplug pass through the connecting wire respectively with spiral device is connected be equipped with the control button who is used for controlling the automatic rolling of connecting wire on the outer wall of earplug box the outside of earplug box is equipped with the sucking disc of being made by the silica gel material, the sucking disc is used for when need not using silencing earphone will the earplug box adsorbs on nuclear magnetic resonance examination equipment, the earplug includes the casing, locates the amortization structure and half cladding in the casing removable earplug cover outside the casing, earplug, spiral device, control button, earplug box and connecting wire are formed by non-ferromagnetic material preparation respectively. The silencing earphone for nuclear magnetic resonance examination can be used for nuclear magnetic resonance examination, does not cause danger in the use process, can provide a quiet treatment environment for patients, and provides a good environment for clinical treatment and research.

Description

Silencing earphone for nuclear magnetic resonance examination

[ field of technology ]

The invention relates to the field of nuclear magnetic resonance, in particular to a silencing earphone for nuclear magnetic resonance examination.

[ background Art ]

The nuclear magnetic resonance imaging technology is an application of nuclear magnetic resonance in the medical field, because the human body contains very rich water, different tissues and different water contents, if the distribution information of the water can be detected, a relatively complete internal structure image of the human body can be drawn, and the nuclear magnetic resonance imaging technology is a technology for estimating the distribution of water molecules in the human body by identifying the distribution of hydrogen atom signals in the water molecules, so that the internal structure of the human body is detected. The nuclear Magnetic Resonance (MRI) inspection machine equipment provides two mutually perpendicular gradient magnetic fields in the direction perpendicular to the main magnetic field, so that the distribution of the magnetic fields in a human body changes along with the change of the spatial position, each position has a magnetic field with different intensity and direction, hydrogen atoms positioned at different parts of the human body react to different radio frequency field signals, and the information of the distribution of water molecules in the space can be obtained through recording the reaction and processing by a computer operation, so that an image of the internal structure of the human body is obtained.

Since a very strong magnetic field exists in the nuclear magnetic resonance machine and the nuclear magnetic resonance examination room, the nuclear magnetic resonance examination is strictly prohibited by the patient with a cardiac pacemaker and the patient with a metal clip, a metal stent or other coronary artery, esophagus, prostate and biliary tract after vascular operation, otherwise, the patient may have serious consequences due to the metal being attracted by the strong magnetic field and being moved, which is dangerous for life. In addition, during the examination process, the metal objects such as necklace, key and the like are strictly forbidden to be kept by the patient and must be removed, otherwise, not only safety accidents are easily caused to the patient, but also the metal objects can be sucked into the nuclear magnetic resonance examination equipment, and damage is caused to the nuclear magnetic resonance examination equipment with very high price.

In nuclear magnetic resonance examinations, considerable noise is generated during the examination, which is caused by the high-speed switching of the currents in the gradient magnetic field coils in the examination apparatus. In order to generate a gradient magnetic field (to locate protons inside an imaging subject) during nuclear magnetic resonance, the coils need to pass through a current, and since the coils themselves are in the magnetic field, the coils are stressed once energized (lorentz force, principle is the same as that of a motor), while MRI requires that the current in these coils be turned on and off at extremely high speeds (clinical sequences typically tens to hundreds of milliseconds for a period, meaning tens of times a second on and off), thus resulting in high frequency vibrations of the coils that can cause the patient to feel tremendous noise. The abnormal activation area of the brain of the patient is easily caused by excessive noise, which affects the judgment of the inspector and the clinician on the treatment or scientific research behaviors, so that the noise generated in the nuclear magnetic resonance inspection process should be reduced as much as possible in order to improve the inspection accuracy.

Since the noise is caused by the nuclear magnetic resonance inspection apparatus, which is expensive, the noise at the time of inspection is unavoidable without replacing the nuclear magnetic resonance inspection apparatus. In order to reduce noise as much as possible, the noise felt by the patient can be reduced only by external auxiliary measures, and the inspection environment is improved.

[ invention ]

The invention aims to solve the problems, and provides the silencing earphone for nuclear magnetic resonance examination, which has the advantages of low cost, convenient manufacture, comfortable wearing and good silencing effect.

The invention provides a silencing earphone for nuclear magnetic resonance examination, which is characterized by comprising two earplugs which can be plugged into human auditory canals and an earplug box for accommodating the earplugs, wherein a wire coiling device is arranged in the earplug box, the earplugs are respectively connected with the wire coiling device through connecting wires, a control button for controlling the connecting wires to be automatically coiled is arranged on the outer wall of the earplug box, an earplug box sucker made of silica gel is arranged on the outer side of the earplug box, the earplug box sucker is used for adsorbing the earplug box on nuclear magnetic resonance examination equipment when the silencing earphone is not needed, and the earplug, the wire coiling device, the control button, the earplug box and the connecting wires are respectively made of nonferromagnetic materials.

The earplug comprises a shell, a silencing structure arranged in the shell and a replaceable earplug sleeve which is semi-coated outside the shell, wherein the shell is made of plastic, the earplug sleeve is made of a silica gel material, the silencing structure comprises a first micro-pore plate, a second micro-pore plate, a sound channel refraction plate, a first piezoelectric ceramic plate, a second piezoelectric ceramic plate and an acoustic resistance plate, the first micro-pore plate and the second micro-pore plate are made of plastic, micro-pores for absorbing sound are arranged on the first micro-pore plate and the second micro-pore plate, a resonance cavity for resonance silencing is formed by the first micro-pore plate and the second micro-pore plate at intervals, a plurality of air channels are formed in the sound channel refraction plate, the air channels penetrate through to form a labyrinth channel for resisting silencing, air holes are formed in the first piezoelectric ceramic plate and the second piezoelectric ceramic plate, the edges of the air holes are coated by titanium metal materials, the resonance frequencies of the first piezoelectric ceramic plate and the second piezoelectric ceramic plate are different, and the first piezoelectric ceramic plate and the second piezoelectric ceramic plate are made of silica gel, and conical through holes for noise reduction are formed in the first micro-pore plate and the second micro-pore plate.

The thickness of the first micro-pore plate is 0.1-0.5 mm, the thickness of the second micro-pore plate is twice that of the first micro-pore plate, and the diameters of the micro-pores on the first micro-pore plate and the second micro-pore plate are 0.5-1 mm.

The thickness of the resonant cavity is 1-5 mm, and the resonant cavity is filled with porous rock wool material.

The dimensions of the air passages on the channel refraction plate are not identical.

The first piezoelectric ceramic piece and the second piezoelectric ceramic piece have different resonant frequencies, the thickness of the first piezoelectric ceramic piece and the second piezoelectric ceramic piece is 0.1-0.3 millimeter, and the diameter of the upper vent hole of the first piezoelectric ceramic piece and the second piezoelectric ceramic piece is 1-1.5 millimeters.

The shell is configured to comprise an outer flat plate part which is away from the auditory canal and a connecting part for sleeving the earplugs, the outer flat plate part is made of plastic, the outer side surfaces of the flat plate parts are respectively provided with an earplug sucking disc, the earplug sucking discs on the two earplug outer flat plate parts are staggered, when the outer flat plate parts of the two earplugs are opposite, the earplug sucking discs can be adsorbed on the surface of the outer flat plate part of the other earplug opposite to the outer flat plate parts; the connecting part is disc-shaped, the size of the connecting part is that the connecting part can be plugged into the external hole of the auditory canal, and the earplug sleeve is detachably sleeved on the connecting part.

The earmuff is of a hollow structure and is configured to comprise an auditory canal insertion part capable of being inserted into an auditory canal and a limiting part for preventing the earplug from loosening from the auditory canal, and the auditory canal insertion part and the limiting part are integrally formed and are made of silica gel.

The earplug is characterized in that a layer of silencing body for silencing is uniformly coated on the inner side surface of the earplug shell, the silencing body is made of a silica gel material, and the silencing structure is arranged in an inner cavity formed by encircling the silencing body.

The present invention has an advantageous contribution in that it effectively solves the above-mentioned problems. The earplug and the earplug box made of nonferromagnetic materials are arranged, so that the earplug and the earplug box can be used for nuclear magnetic resonance examination, no danger is caused in the using process, a quiet treatment environment is provided for a patient, and a good environment is provided for clinical treatment and research. According to the invention, the silencing structure for silencing by means of various silencing principles is arranged in the earplug, so that the silencing effect is greatly improved. In the sound-absorbing structure, the first micro-pore plate and the second micro-pore plate have different thicknesses, different pore diameters and different porosities, so that the width of a sound-absorbing frequency band can be enlarged, and a better sound-absorbing effect is realized. The silencing earphone for nuclear magnetic resonance examination has the advantages of convenient use, good silencing effect, low cost, strong practicability and suitability for popularization.

[ description of the drawings ]

Fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is a schematic view of the structure of two earplugs of the present invention when the two earplugs are attached together.

Fig. 3 is an exploded partial cross-sectional view of an earplug and earmuff of the invention.

The earplug 1, the case 11, the outer flat plate 111, the connection part 112, the sound attenuating structure 12, the first micro-hole plate 121, the second micro-hole plate 122, the sound channel refraction plate 123, the air channel 1231, the first piezoelectric ceramic plate 124, the second piezoelectric ceramic plate 125, the sound resistance plate 126, the tapered through hole 1261, the resonance cavity 127, the earplug cover 13, the ear canal insertion part 131, the restriction part 132, the earplug suction cup 14, the sound attenuating body 15, the earplug case 2, the earplug case suction cup 21, the control button 22, the accommodation cavity 23, and the connection wire 3.

[ detailed description ] of the invention

The following examples are further illustrative and supplementary of the present invention and are not intended to limit the invention in any way.

As shown in fig. 1 to 3, the noise reduction earphone for nuclear magnetic resonance examination of the present invention includes an earplug 1 and an earplug case 2 for accommodating the earplug 1.

The shape of the earplug case 2 may be set according to aesthetic needs, and it may be set in a round box shape, a square box shape, or a cartoon shape, and in this embodiment, the earplug case 2 is configured in a square box shape. To improve the safety of use, the earplug case 2 is made of a non-ferromagnetic material, in this embodiment the earplug case 2 is made of plastic. Because nuclear magnetic resonance inspection equipment is high in price and is matched with the existing nuclear magnetic resonance inspection equipment for use, and cost is reduced, in the invention, the earplug box sucker 21 is arranged on the outer side surface of the earplug box 2, and the earplug box sucker 21 is made of a silica gel material. When in use, the earplug box 2 can be taken down, and when not in use, the earplug box 2 can be adsorbed on the surface of nuclear magnetic resonance examination equipment, thereby preventing loss.

In order to prevent individual earplugs 1 from falling off or being lost during use, the earplugs 1 are connected together by a connecting cord 3 in the present invention. For the convenience of accomodating the inside of earplug box 2 is equipped with spiral device, earplug 1 respectively through connecting wire 3 with spiral device is connected, from when needing to use, but pull earplug 1 and extension connecting wire 3's length, when not needing to use, spiral device can be automatic with connecting wire 3 rolling. For facilitating automatic winding, a control button 22 for controlling automatic winding is provided on the outer wall of the earplug case 2. The winding device and the arrangement of the control button 22 can be referred to in the prior art, and this embodiment is not described in detail.

The earplug case 2 is configured to have a receiving cavity 23 for receiving the two earplugs 1, and the side walls of the earplug case 2 are respectively provided with a notch 24 for convenient storage, the notch 24 is communicated with the receiving cavity 23, so that the connecting wire 3 can be clamped into the notch 24, and the earplugs 1 can be conveniently placed into the receiving cavity 23 of the earplug case 2. The earplug case 2 may adopt a well-known flip cover structure, and when in use, the earplug 1 may be taken out by opening the flip cover, and when not in use, the earplug 1 is accommodated in the accommodating cavity 23 by closing the flip cover.

The earplug 1 is used for silencing and reducing noise interference in the nuclear magnetic resonance inspection process, and comprises a shell 11, a silencing structure 12 and a plug sleeve 13. The silencing structure 12 is used for silencing and is arranged inside the shell 11. The earplug cover 13 is arranged on the shell 11 in a semi-cladding mode and can be separated from the shell 11. The earmuff 13 is used for improving the wearing comfort of the earplug 1 and is convenient for different patients to replace wearing so as to ensure the sanitation of use.

The housing 11 is constructed in a closed shape, and has a cavity therein for providing the sound deadening structure 12. In order to facilitate that the earplug 1 does not fall when not worn, in this embodiment, an earplug suction cup 14 is respectively disposed on the outer side surface of the housing 11, and is used for enabling the two earplugs 1 to be oppositely combined and absorbed together to be sleeved on the neck, so as to prevent the earplug 1 from falling off. In particular, the housing 11 is configured to include an outer flat portion 111 facing away from the ear canal and a connecting portion 112 for receiving the earbud 13. The outer surface of the outer flat plate portion 111 is smooth and planar for allowing the earplug suction cup 14 to be sucked thereto. The outer flat plate portion 111 is made of plastic. The outer flat portions 111 of the two earplugs 1 are identical in shape, and the earplug suction cups 14 on the outer flat portions 111 of the two earplugs 1 are positioned so as to be staggered from each other, so that when the outer flat portions 111 of the two earplugs 1 are opposed, the earplug suction cups 14 can be attracted to the surface of the outer flat portion 111 of the other earplug 1 opposed thereto. The outer flat plate portion 111 is sized so that at least two earplug suction cups 14 may be disposed thereon. The connecting portion 112 is used for sleeving the earplug cover 13, and is disc-shaped, and has a size that the earplug cover can be plugged into an external hole of the auditory canal to isolate the auditory canal from external sound sources. In this embodiment, the connecting portion 112 is made of plastic material.

The earplug cover 13 is used to cover the connection portion 112 of the earplug 1, and is made of silica gel material. The earplug cover 13 is hollow so as to accommodate ear canals of different shapes and sizes. To improve wearing comfort, the earplug cover 13 is configured to include an ear canal insertion portion 131 and a restricting portion 132 for preventing the earplug 1 from being released from the ear canal. The ear canal insertion part 131 can be inserted into the deep of the ear canal, and the ear plug sleeve 13 has a hollow silica gel structure, so that when the ear canal insertion part 131 is inserted into the deep of the ear canal of a patient, the ear canal insertion part can adapt to the shape of the ear canal and fit with the ear canal, thereby improving wearing comfort. The restraining portion 132 is adapted to engage at the pinna, thereby preventing the earplug 1 from loosening. The limiting portion 132 is integrally formed with the earplug cover 13, and is made of a silicone material.

The silencing structure 12 includes a first micro-porous plate 121, a second micro-porous plate 122, a sound-channel refraction plate 123, a first piezoelectric ceramic plate 124, a second piezoelectric ceramic plate 125, and an acoustic resistance plate 126.

The first microplate 121 and the second microplate 122 are made of plastic, and have smooth surfaces, which is advantageous for reflection of sound waves. The thickness of the first micro-porous plate 121 is 0.1-0.5 mm, and the thickness of the second micro-porous plate 122 is twice the thickness of the first micro-porous plate 121. In this embodiment, the thickness of the first microplate 121 is preferably 0.3 mm, and the thickness of the second microplate 122 is preferably 0.6 mm. A plurality of micropores are respectively arranged on the first microporous plate 121 and the second microporous plate 122, and the diameter of each micropore is 0.5-1 mm. In this embodiment, the diameters of the micropores on the first microporous plate 121 and the second microporous plate 122 are different, and the porosities are different, so that the silencing frequency band can be enlarged conveniently; the diameter of the micro holes of the first micro hole plate 121 is preferably 0.5 mm, and the diameter of the micro holes of the second micro hole plate 122 is preferably 0.8 mm. The first microplate 121 and the second microplate 122 are spaced apart from each other, so as to form a resonant cavity 127 for resonance noise reduction. The first and second microwells 121 and 121 are spaced apart by a distance of 1 to 5 mm, preferably 2 mm. In addition, for further improving the noise reduction and noise attenuation purposes, the resonant cavity 127 may be filled with a porous rock wool material, and the resistive sound of the porous rock wool material may be utilized. The porous rock wool material has high sound absorption coefficient, wide absorption frequency band, low pressure loss and low air flow regeneration noise, so that the silencing effect can be further improved.

The acoustic channel refraction plate 123 serves to enhance reflection and refraction of the acoustic wave and change a propagation direction of the acoustic wave, thereby realizing resistive sound attenuation. The refraction board 123 is made of plastic, and a plurality of air passages 1231 are arranged on the refraction board, and the air passages 1231 are communicated to form a labyrinth passage. The dimensions of the air passages 1231 are not completely the same, when the sound wave propagates, the sound wave with certain frequency can be emitted, refracted, interfered and the like at the interface with abrupt change of acoustic impedance due to the change of the dimensions of the air passages 1231 and the change of the circulation direction of the air passages 1231, so that the purpose of silencing is achieved.

The resonant frequencies of the first piezoelectric ceramic sheet 124 and the second piezoelectric ceramic sheet 125 are different, wherein the resonant frequency of the first piezoelectric ceramic sheet 124 is 2.5kHz, and the thickness thereof is 0.1 to 0.3 mm, preferably 0.2 mm. The second piezoceramic sheet 125 has a resonance frequency of 5kHz and a thickness of 0.1 to 0.3 mm, preferably 0.2 mm. Air holes are respectively arranged on the first piezoelectric ceramic piece 124 and the second piezoelectric ceramic piece 125, and the diameter of each air hole is 1-1.5 mm, preferably 1 mm. The edges of the air holes are covered by plastic. When the sound wave passes through the first piezoelectric ceramic plate 124 and the second piezoelectric ceramic plate 125, the piezoelectric ceramic plates convert the absorbed sound energy into voltage, and the positive and negative electrodes formed on the piezoelectric ceramic plates through the edges of the air holes are shorted, so that the sound wave energy is consumed, and the purpose of noise reduction is achieved.

The acoustic resistance sheet 126 is used for further consuming acoustic energy to reduce noise, and the acoustic resistance sheet 126 is made of a silica gel material and provided with a plurality of conical through holes 1261. The silica gel material can be used for absorbing sound, and the conical through hole 1261 arranged on the silica gel material is favorable for changing the sound resistance value, so that the sound waves are emitted, refracted, interfered and the like at the interface of the conical through hole 1261 with abrupt change of the sound resistance value, and the purpose of silencing is achieved.

In order to further enhance the silencing effect as a whole, a silencing body 15 is filled between the housing 11 and the silencing structure 12, and the silencing body 15 is made of a silica gel material.

Thus, the silencing earphone for nuclear magnetic resonance examination of the invention is formed. Because each part of the earphone is made of nonferromagnetic materials, the earphone can be used in nuclear magnetic resonance examination, so that noise is eliminated to the greatest extent for patients, a good external environment is provided for clinical treatment and scientific research of nuclear magnetic resonance examination of brain functional diseases, and a quiet treatment environment is provided for relieving the emotion of the patients. When not in use, the earplug 1 is contained in the containing cavity 23 of the earplug box 2, the connecting wire 3 is wound inside the earplug box 2, and the earplug box 2 is adsorbed on the surface of nuclear magnetic resonance examination equipment, so that the earplug box is convenient to take during use. When the nuclear magnetic resonance examination device is needed to be used, the earplug box 2 is taken down, the earplug 1 is taken out, the connecting wire 3 is pulled to a required length and then sleeved at the back of the neck, and when nuclear magnetic resonance examination equipment is not entered, in order to prevent the earplug 1 or the earplug box 2 from falling, the two earplugs 1 can be oppositely combined and adsorbed together, so that the earplug 1 is annularly sleeved on the neck. When entering the nuclear magnetic resonance examination apparatus, the two earplugs 1 are separated, and then the earplug cover 13 of the earplug 1 is inserted into the auditory canal, so that the auditory canal insertion part 131 of the earplug cover 13 is inserted into the deep part of the auditory canal, and the limiting part 132 of the earplug cover 13 is limited at the auricle to avoid the loosening of the earplug 1. When used, the earplug 1 is removed and the earplug cover 13 is discarded or cleaned, and then the earplug 1 is placed in the earplug case 2, and the earplug case 2 is sucked at the corresponding position of the nuclear magnetic resonance examination apparatus. The silencing earphone for nuclear magnetic resonance examination can be conveniently fixed in the existing nuclear magnetic resonance examination equipment, is matched with the nuclear magnetic resonance examination equipment for use, and has strong practicability. In addition, the silencing earphone for nuclear magnetic resonance examination is made of non-ferromagnetic materials, so that the silencing earphone does not cause danger in the use process, and can be used for nuclear magnetic resonance examination. In addition, the sound attenuation structure 12 provided by the invention not only utilizes the resistance of the sound absorption material to absorb sound, but also utilizes the sound resistance value mutation to realize resistance sound attenuation, so that the sound attenuation effect of the earplug 1 can be greatly improved, a quiet treatment environment is provided for patients, and a good research environment is provided for clinical treatment and research. In the sound attenuation structure 12 of the present invention, the first micro-porous plate 121 and the second micro-porous plate 122 have different thicknesses, different pore diameters and different porosities, so that the width of the sound absorption frequency band can be enlarged, and a better sound attenuation effect can be realized.

Although the present invention has been disclosed by the above embodiments, the scope of the present invention is not limited thereto, and each of the above components may be replaced with similar or equivalent elements known to those skilled in the art without departing from the spirit of the present invention.

Claims

1. The utility model provides a noise reduction earphone for nuclear magnetic resonance examination, its characterized in that includes two earplug (1) that can be used to pack into human auditory canal and is used for accomodating earplug (1) earplug box (2) in be equipped with spiral device, earplug (1) respectively through connecting wire (3) with spiral device is connected, be equipped with on the outer wall of earplug box (2) and be used for controlling connecting wire (3) automatic rolling control button (22), be equipped with earplug box sucking disc (21) made by silica gel material in the outside of earplug box (2), earplug box sucking disc (21) are used for adsorbing earplug box (2) on nuclear magnetic resonance examination equipment when need not use noise reduction earphone, earplug (1), spiral device, control button (22), earplug box (2) and connecting wire (3) are made by non-ferromagnetic material respectively;

the earplug (1) comprises a shell (11), a silencing structure (12) arranged in the shell (11) and a replaceable earplug sleeve (13) which is semi-coated outside the shell (11), the shell (11) is made of plastic, the earplug sleeve (13) is made of silica gel material, the silencing structure (12) comprises a first micro-pore plate (121), a second micro-pore plate (122), an acoustic channel refraction plate (123), a first piezoelectric ceramic piece (124), a second piezoelectric ceramic piece (125) and an acoustic resistance piece (126), the first micro-pore plate (121) and the second micro-pore plate (122) are made of plastic, micro-pores for sound absorption are arranged on the first micro-pore plate (121) and the second micro-pore plate (122), a resonance cavity (127) which can be used for silencing is formed at intervals, the acoustic channel refraction plate (123) is made of plastic, a plurality of air channels (1231) are arranged on the acoustic channel refraction plate, the air channels (1231) penetrate through to form a sound-damping channel, the first micro-pore plate (121) and the second micro-pore plate (121) are made of plastic, the first piezoelectric ceramic piece (124) and the second piezoelectric piece (125) are made of ceramic piece (124) are made of the same as the acoustic resistance piece, and the first piezoelectric piece (125) and the second piezoelectric piece (124) are made of the piezoelectric piece (124) and the piezoelectric piece (124) are made of the same frequency, on which a conical through hole (1261) for noise reduction is provided.

2. The noise reduction earphone for nuclear magnetic resonance examination according to claim 1, wherein the thickness of the first micro-porous plate (121) is 0.1 to 0.5 mm, the thickness of the second micro-porous plate (122) is twice the thickness of the first micro-porous plate (121), and the diameters of the micro-pores on the first micro-porous plate (121) and the second micro-porous plate (122) are 0.5 to 1 mm.

3. The noise-reducing earphone for nuclear magnetic resonance examination according to claim 2, wherein the thickness of the resonance chamber (127) is 1-5 mm, and the inside thereof is filled with a porous rock wool material.

4. A sound attenuating earphone for nuclear magnetic resonance examination as claimed in claim 3, characterized in that the air passages (1231) on the sound track refraction plate (123) are not of exactly the same size.

5. The noise reduction earphone for nuclear magnetic resonance examination according to claim 4, wherein the resonance frequencies of the first piezoelectric ceramic sheet (124) and the second piezoelectric ceramic sheet (125) are different, the thickness thereof is 0.1-0.3 mm, and the diameter of the ventilation hole is 1-1.5 mm.

6. The noise-reducing earphone for nuclear magnetic resonance examination according to claim 5, characterized in that the housing (11) is configured to include an outer flat plate portion (111) facing away from the auditory canal and a connecting portion (112) for sleeving an ear plug sleeve (13), the outer flat plate portion (111) being made of plastic, one ear plug suction cup (14) being provided on each of the outer surfaces of the flat plate portions, the positions of the ear plug suction cups (14) on the outer flat plate portions (111) of the two ear plugs (1) being staggered with respect to each other, such that the ear plug suction cups (14) are adsorbable on the surface of the outer flat plate portion (111) of the other ear plug (1) facing thereto when the outer flat plate portions (111) of the two ear plugs (1) are facing each other; the connecting part (112) is disc-shaped and has a size that the connecting part can be plugged into an external hole of an auditory canal, and the earplug cover (13) is detachably sleeved on the connecting part (112).

7. The noise-reducing earphone for nuclear magnetic resonance examination according to claim 6, wherein the earplug cover (13) is of a hollow structure configured to include an ear canal insertion portion (131) that can be inserted into an ear canal and a restricting portion (132) for preventing the earplug (1) from being released from the ear canal, the ear canal insertion portion (131) and the restricting portion (132) being integrally formed of silicone rubber.

8. The silencing earphone for nuclear magnetic resonance examination as claimed in claim 7, wherein a layer of silencing body (15) for silencing is uniformly coated on the inner side surface of the shell (11) of the earplug (1), the silencing body (15) is made of a silica gel material, and the silencing structure (12) is arranged in an inner cavity surrounded by the silencing body (15).