CN101217828A - Noise suppression device and method - Google Patents

Abstract

The invention is a noise suppression device and method, the said apparatus is mainly formed by a cavity, plural conduit, an electroacoustic transducer, a loudspeaker and a noise suppression circuit, wherein a conduit connects the said cavity in order to provide the outside sound wave signal to enter the said cavity, and a conduit connects the said cavity in order to send the sound wave signal after processing into the ear canal; the electroacoustic transducer is used for receiving the sound wave signal entering the cavity, converting the sound wave signal into an electronic signal and then sending the electronic signal to the noise suppression circuit; the loudspeaker is used for receiving the electronic signal generated by the noise suppression circuit and generating an inverse sound wave signal; the high-frequency noise signal can be suppressed through the low-pass acoustic wave filter formed by the guide pipe and the cavity, and the reversed-phase acoustic wave signal has better noise suppression effect on the noise with lower frequency in the cavity; the aim of noise resistance in full frequency is achieved by combining the two noise suppression effects.

Description

Noise suppression device and method

technical field

The present invention relates to a noise suppression device and method, especially a device that combines a noise suppression circuit system and a cavity structure designed with an appropriate size. The noise suppression circuit generates anti-phase sound waves to suppress low-frequency noise. The above-mentioned cavity forms a low-pass acoustic wave filter to suppress high-frequency noise, so as to achieve the purpose of anti-noise at all frequencies.

Background technique

Long-term exposure to noise can easily lead to hearing loss in the ears, and excessive noise can make people feel uncomfortable. In recent years, due to the popularity of portable audio-visual equipment, the number of people who use headphones to listen to music has increased. When users are exposed to noisy environments, they often turn up the volume of the headphones because they cannot hear the sound of the outside world. damage to the eardrum.

Taking earphone products as an example, the earphones with noise suppression effect in general earphones can be roughly divided into earmuffs and earplugs. Traditional earmuffs usually have a bulky earmuff, and most of the earmuffs are made of Foam is used as a sound insulation material, and the user sets the earmuffs outside the ears, and the ears can be wrapped in the earmuffs, so as to prevent external noise from entering, but it is not conducive to carrying because of its bulky size; as for earphones, It can put the earphone into the ear, and through the tight fit formed between the earphone and the ear, the earphone can be fixed in the ear, and the external noise can be blocked. Although the earplug-like earphone has the advantage of being easy to carry, However, compared with the earmuff type earphones, although the sound insulation effect of the earplug type earphones is better, but because they are completely sealed, the air pressure will be unbalanced, and the so-called internal body noise will be heard, that is, when the user uses it, he will hear it. Talking, swallowing, or even the movement of body muscles and joints cause various internal sounds, and there is a feeling of suffocation and discomfort.

Due to the poor sound insulation effect of the existing earmuff structure, there is a design combined with an active circuit design to filter out noise, such as the US Patent No. 4455675 "Head phoning". The above case first proposes a sound control system, which It is to generate sound waves through a sound sensing device to eliminate unwanted sound waves by interference. The above-mentioned type of technology is currently widely used by related industries, but the preferred applicable frequency range of the above-mentioned type of noise suppression method is a frequency range of several kHz The following low-frequency noise, and high-frequency noise, because the phase cannot be synchronized, resulting in poor anti-noise effect, it still needs to be eliminated by earmuffs; as for the patents of various countries that have been proposed in the later period to suppress noise, such as the US invention patent 4985925 No. "Active noise reduction system", the electronic components or circuit layouts may be different, but none of them can escape the design method of actively suppressing noise by the circuit, so high-frequency noise cannot be eliminated.

Please refer to U.S. Patent No. 6,683,965 "In-the-ear noise reduction headphones" shown in Fig. 1, the case proposes an earphone inserted into the ear canal, and the earphone has an outer casing 14, and the outer casing The body 14 includes an extension part 16 that can be put into the ear canal (not shown in the figure), and the outer shell 14 has an inner cavity 28, and the inner cavity 28 is connected to the passage 29 in the extension part 16. In the same way, its speaker 32 is configured in the channel 29, and the microphone 34 is configured in the space below the speaker 32 and the channel 29, through the configuration of the speaker 32 and the microphone 34, and the channel 29 and the ear canal produce the coupling or transmission of the sound field to achieve the purpose of reducing noise, but the cavity 28 and the channel 29 have no filtering effect and cannot filter out high-frequency noise.

Please refer to the Taiwan New Patent Application No. 91213715 "Feedback Active Noise Control Earphone" shown in Fig. On the contrary, the sound wave signal is then sensed by the microphone sensor 120 to detect the ambient noise of the speaker 110 and converted into a noise sensing signal, because the microphone sensor 120 is arranged in front of the speaker 110 and is located at the The front of the speaker 110 is in the energy vortex 150 generated in the earmuffs 140 due to the near-field effect, so it can suppress the reception of low-frequency noise, and can cancel each other with the anti-phase sound waves generated by the speaker 110; For low-frequency noise cancellation, the location of the microphone sensor 120 is limited to the front of the speaker 110 , and the earmuffs 140 and the active noise control circuit 130 must be matched at the same time.

Contents of the invention

In view of the defects of the prior art, the main purpose of the present invention is to propose a noise suppression device, which combines the noise suppression circuit and a cavity structure designed with appropriate dimensions, suppresses low-frequency noise through the noise suppression circuit, and suppresses low-frequency noise through the cavity The body forms a low-pass sound field filter to suppress high-frequency noise, so as to achieve the purpose of anti-noise at all frequencies.

A secondary purpose of the present invention is to provide a noise suppression device that can improve the discomfort caused by unbalanced ear pressure when the traditional earphone suppresses external noise in a sealed manner.

To achieve the above object, the present invention proposes a noise suppression device, which includes:

a cavity;

A plurality of conduits are used to connect the cavity, provide acoustic signals including noise signals to enter and exit the cavity, and form a component of an acoustic filter; a noise suppression circuit is used to receive the acoustic signal including noise signals Acoustic signals and can generate electronic signals;

An electroacoustic sensor is used to receive the acoustic signal in the cavity, convert it into an electronic signal and send it to the noise suppression circuit; and

A loudspeaker is used to receive the electronic signal generated by the noise suppression circuit and generate an anti-phase sound wave signal superimposed on the sound wave signal in the cavity, and the noise signal in the cavity with the noise signal in the cavity Interference cancellation effect occurs in the cavity.

Preferably, the sectional area of the cavity is larger than the sectional area of the conduit.

Preferably, the length of the cavity may not be equal to the length of the catheter.

Preferably, the plurality of conduits include:

an outer catheter, which is a conduit for providing said acoustic signal into said cavity;

An inner conduit is a pipe used to send the acoustic wave signal canceled by the high-frequency noise out of the cavity.

Preferably, the cross-sectional area and length of the outer conduit may be different from the cross-sectional area and length of the inner conduit.

Preferably, the electroacoustic sensor is connected to a feedback circuit, and the sound wave signal is inverted to the speaker through the feedback circuit.

Preferably, it also includes a housing for accommodating the cavity, conduit, electroacoustic sensor and speaker.

Preferably, the cavity and the conduit are integrally formed with the casing.

Preferably, the housing is provided with an earplug structure at the end of the conduit that sends out sound waves, for plugging into the human ear canal and preventing noise from leaking into the ear canal.

Preferably, the housing has a circuit connection hole for providing the electroacoustic sensor with a wired connection to an external circuit.

Preferably, the casing has a circuit connection hole for providing the speaker with a wired connection to an external circuit.

Preferably, the electroacoustic sensor and the speaker can be connected to external circuits in a wired or wireless manner.

Preferably, the electroacoustic sensor is arranged between the loudspeaker and the external auditory canal.

Preferably, an opening is provided between the electroacoustic sensor and the cavity for the electroacoustic sensor to receive the acoustic signal in the cavity through the opening, so The direction in which the electro-acoustic sensor receives the sound wave signal through the opening is perpendicular to the transmission direction of the sound wave input from the catheter to the cavity.

Preferably, chamfers are provided at the connection between the interior of the cavity and the conduit.

Preferably, the inner wall of the cavity is provided with sound-absorbing materials.

Preferably, the opposite inner sidewalls of the cavity are not parallel to each other.

Preferably, the cavity can be of regular or irregular shape.

Preferably, the conduit can be of regular or random irregular shape.

In order to achieve the above object, the present invention further proposes a noise suppression method, which includes:

providing an outer conduit to allow acoustic signals to enter a cavity;

An electroacoustic sensor receives the noise signal in the cavity and converts it into an electronic signal;

A noise suppression circuit receives the electronic signal generated by the electroacoustic sensor, and generates an anti-phase sound wave signal through the speaker; the anti-phase sound wave signal generated by the speaker and the noise signal in the cavity are in the Interference offset effect occurs in the cavity;

The noise-canceled sound wave signal is sent out of the cavity through an inner conduit.

Preferably, the noise suppression circuit includes a feedback circuit through which the electronic signal is sent to the speaker to generate an anti-phase sound wave signal

The acoustic filter structure formed by the duct and the cavity can suppress high-frequency noise that cannot be offset by noise control, and the combination of the two can achieve full-frequency noise cancellation.

Description of drawings

Fig. 1 is the structural representation of existing No. 6683965 U.S. Patent;

Fig. 2 is the structure schematic diagram of No. 91213715 Taiwan patent of prior application;

Fig. 3 is a structural representation of the present invention;

Fig. 4 is a schematic diagram of the present invention implemented in a human ear;

FIG. 5 is a structural diagram of an active noise suppression circuit of the present invention;

Fig. 6 is a spectrum diagram of the unattenuated energy of the noise passing through the cavity when the present invention simulates the design of the cross-sectional areas of the outer catheter, the cavity and the inner catheter;

Fig. 7 is the frequency spectrum diagram of the energy attenuation of the noise through the cavity when simulating the unequal cross-sectional area design of the outer catheter, the cavity and the inner catheter in the present invention;

Fig. 8 is a measurement diagram of the characteristics of suppressing high-frequency noise of the present invention.

Description of reference signs: 10-noise suppression device; 1-outer conduit; 11-input end; 12-output end; 2-cavity; 3-inner conduit; 31-input end; 32-output end; 4-speaker; 41-opening; 42-circuit hole; 43-amplifier (Power Amp); 5-electroacoustic sensor; 51-opening; 52-circuit hole; 53-preamplifier; 6-housing; 61-earplug structure; 7-human ear; 71-external auditory canal; 72-pinna; 73-tympanic membrane; 20-noise suppression control process; 21-gain loop; 22-noise signal; 23-acoustic interface; L1-length of external catheter; L2-cavity The length of the body; L3-the length of the inner catheter; S1-the cross-sectional area of the outer catheter; S2-the cross-sectional area of the cavity; S3-the cross-sectional area of the inner catheter.

Detailed ways

The technical means and effects used by the present invention to achieve the purpose will be described with reference to the drawings, and the embodiments listed in the drawings are only for auxiliary explanation, so as to facilitate the review committee to understand that the technical means of this case are not limited to the listed ones. Schema.

First of all, the main structure of the present invention can be divided into two parts, one is the design of the acoustic filter structure, and the other is the design of the suppression circuit. For the design of the acoustic filter structure, please refer to Figures 3 and 4. The noise suppression The device 10 comprises a housing 6, and a cavity 2 is provided in the housing 6, assuming that the cross-sectional area of the cavity 2 is S2 and the length is L2; An outer conduit 1 and an inner conduit 3 are respectively provided at both ends, the outer conduit 1 has an input end 11 and an output end 12, and the input end 11 passes through the housing 6 to communicate with the external environment, The input end 12 is connected to and passes through the cavity 2, assuming that the cross-sectional area of the outer conduit 1 is S1 and the length is L1; moreover, the inner conduit 3 has an input end 31 and An output end 32, the input end 31 is connected to and passes through the cavity 2, the output end 32 passes through the housing 6, and can communicate with the external auditory canal 71 of the human ear, assuming that the The cross-sectional area of the inner conduit 3 is S3, and the length is L3; through the outer conduit 1 and the inner conduit 3 passing through the cavity 2, the cavity 2 and the housing 6 In communication with the external environment, an earplug structure 61 is provided on the housing 6 corresponding to the output end 32 of the inner conduit 3. The earplug structure 61 is generally made of soft rubber, plastic or foam. It can be used to plug into the external auditory canal 71 of the human ear 7 to prevent noise from leaking into the external auditory canal 71 from non-device parts, and the housing 6 outside the earplug structure 61 can be built in the auricle 72 of the human ear 7 ; The size, shape or material of the earplug structure 61 is not limited, and the one that is close to the external auditory canal 71 and comfortable is the best. According to the actual design of the size of the housing 6 or the shape or material of the earplug structure 61, the configuration of the earplug structure 61 and the housing 6 can be changed in other ways; The cavity 2 has an outer conduit 1 and an inner conduit 3 respectively connecting the external environment and the external auditory canal 71, so it has the function of balancing the inner and outer ear pressure under static pressure, and has the effect of suppressing high-frequency noise under dynamic pressure.

Furthermore, an electro-acoustic sensor 5 is provided in the housing 6. Usually, the electro-acoustic sensor 5 can adopt a miniature microphone, and a There is an opening 51, so that the electroacoustic sensor 5 can measure the acoustic wave signal inside the cavity 2 through the opening 51, and the size of the opening 51 is based on the actual use of the electroacoustic sensor 5 Depends on the type; the housing 6 is provided with a circuit connection hole 52 corresponding to the electroacoustic sensor 5, and the circuit connection hole 52 is used to provide the wired connection of the electroacoustic sensor 5 External circuit; it must be noted that the direction A in which the electroacoustic sensor 5 receives the acoustic signal through the opening 51 is the same as the transmission direction B in which the external catheter 1 inputs the acoustic signal to the cavity 2 vertical.

Secondly, a loudspeaker 4 is provided in the housing 6, generally, the loudspeaker 4 can be a horn, and an opening 41 is provided between the cavity 2 and the loudspeaker 4, so that the The loudspeaker 4 can send the sound wave signal into the inside of the cavity 2 through the opening 41, and the size of the opening 41 depends on the type of the loudspeaker 4 actually used; 6 Correspondingly, a circuit connection hole 42 is provided at the speaker 4, and the circuit connection hole 42 is used to provide the speaker 4 with a wired connection to an external circuit; If conditions permit, the electroacoustic sensor 5 and the speaker 4 can also be connected to an external circuit in a wireless manner.

The material of the housing 6 is indeterminate, usually plastic material, and the outer conduit 1, the cavity 2 and the inner conduit 3 can be integrally formed in the housing 6; the present invention The feature is that the dimensions of the outer catheter 1, the cavity 2 and the inner catheter 3 match each other, and the cross-sectional area S2 of the cavity 2 must be larger than the outer catheter 1 and the inner catheter 3 respectively. The cross-sectional areas S1, S3 of the outer catheter 1, the inner catheter 3 and the cavity 2 can be in any regular or irregular shape, but preferably circular, the outer catheter 1. The lengths L1, L2, and L3 of the cavity 2 and the inner catheter 3 can be different from each other, and the outer catheter 1 and the inner catheter 3 can be in any regular or curved irregular shape; in addition, In order to avoid the reflection of the acoustic wave signal in the cavity 2, chamfering can be provided at the connection between the inside of the cavity 2 and the outer conduit 1 and the inner conduit 3, or the cavity The opposite inner walls of the body 2 are set to be non-parallel to each other, or a sound-absorbing material (such as foam) is set in the cavity 2 .

Through the change of the cavity volume of the outer catheter 1, the cavity 2 and the inner catheter 3 and the diameter of the catheter, the cavity 2 forms a low-pass filter through which low-frequency sound waves can pass. It is actually required to increase the number of conduits to improve the sound wave filtering effect of the cavity 2. Here, only an outer conduit 1 and an inner conduit 3 are used as an example to illustrate the cavity 2; when the casing 6 The noise sound wave signal generated by the external environment enters through the input end 11 of the outer catheter 1 and reaches the cavity 2, and when it is output by the inner catheter 3, the high frequency noise of the noise sound wave signal The signal will be suppressed because of the structure of the sound wave filter formed by the cavity 2 (the high frequency noise signal range is defined as 1KHz to about 20KHz, which is the limit of human hearing), and the low frequency noise signal of the noise sound wave signal ( The range of the low-frequency noise signal is defined as a sound signal with a frequency of 1 kHz to several KHz), and the electro-acoustic sensor 5 is used to receive the noise signal, and the noise signal is converted into an electronic signal through a feedback circuit (not shown in the figure). signal, the anti-phase sound wave signal is generated by the noise suppression circuit, and sent to the loudspeaker 4, and then the loudspeaker 4 generates an anti-phase sound wave signal opposite to the noise signal amplitude and phase, and the described The anti-phase sound wave signal is transmitted to the cavity 2, the anti-phase sound wave signal is superimposed on the sound wave signal in the cavity 2, and can be combined with the noise signal in the cavity 2 in the The interference canceling effect is generated in the cavity 2, so as to eliminate the low-frequency noise signal that the cavity 2 cannot suppress, in other words, through the combination of the passive acoustic wave filter and the noise suppression circuit, high-frequency noise can be suppressed Signal and low frequency noise signal, to achieve full frequency noise suppression effect. When applied to headphones, because the anti-phase noise suppression sound wave signal is superimposed on the sound wave signal to be received, the anti-phase noise suppression sound wave signal will only interfere with the noise suppression signal, and will not affect the sound wave signal to be received and the sound wave signal sent by the speaker 4, because it does not pass through the sound wave filter path formed by the outer conduit 1, the cavity 2 and the inner conduit 3, so its high-frequency sound wave signal performance will not suppressed.

The electroacoustic sensor 5 is used to receive noise signals, and is used to control whether the sound wave interference is a convergence phenomenon, to prevent the anti-noise system from resonating and transforming into a noise generator. Therefore, the electroacoustic sensor 5 is arranged on the The front of the loudspeaker 4 described above, that is, between the loudspeaker and the human ear canal 71. In this way, it can be ensured that the noise signal can be fully measured by the electroacoustic sensor 5, and the anti-phase sound wave signal generated by the speaker 4 can completely cancel the noise signal in the cavity 2, so as to protect the eardrum 73 safety, this method is called closed loop feedback control (closed loop feedback control); on the other hand, the speakers and microphones of some traditional noise suppression systems place the electroacoustic sensor 5 behind the speaker 4 to prevent external noise The electroacoustic sensor 5 will be used first, and then the speaker 4 will be controlled by the circuit signal to generate an anti-phase signal. In this way, it is impossible to ensure whether the interference sound waves entering the ear are convergent interference rather than additive sound waves. If the feedback circuit does not handle it properly, it will cause unpredictable damage to the human eardrum 73 .

Regarding the noise suppression circuit of the present invention, since the noise suppression circuit belongs to the prior art, its circuit layout (Layout) method is no longer described in detail, but the noise suppression circuit is used to suppress the noise suppression device 10 low-frequency noise signal, so please refer to shown in Figure 5, the design concept of the control circuit of the present invention and the noise suppression control flow 20 are outlined, which can be divided into the following groups of parameters:

Loudspeaker 4 and amplifier (Power Amplifier) 43, this parameter is set to have sound wave amplification function A;

Electro-acoustic sensor 5 and pre-amplifier (Pre Amplifier) 53, set this parameter as having sound wave amplification function B;

The feedback control parameter C of the gain loop 21;

The sound wave interference phenomenon I of the noise signal 22 refers to the phenomenon that the sound wave signal in the cavity 2 and the anti-phase sound wave signal produced by the loudspeaker 4 cancel each other out;

Feedback control signal processing H is used to synthesize and compare the sound wave signals processed by the pre-amplifier (Pre Amplifier) 5 and the gain loop 21, and adjust to an appropriate size;

The acoustic wave interface 23 described in the figure represents the outer catheter 1 , the cavity 2 and the inner catheter 3 shown in FIG. 3 .

Assuming that the noise signal (Noise) is P(n) and the speaker output signal is P(v), since the transmission speed of sound waves is much slower than that of electrical signals, the noise signals are sorted by time (P(n), P(n+1 ), P(n+2)…), the logic control is as follows:

P(v)＝-ABC□P(n)

P(i)=P(v)+P(n+1)=P(n+1)-ABC□P(n)

P(v+1)＝AC(-ABC□P(n))-B□P(i))

＝AC(-BC□P(n)+AB2C□P(n)-B□P(n+1))

When AB=1,

P(v+1)＝-ABC□P(n+1)………(Equation 1)

It can be seen from Formula 1 that the noise feedback control circuit of the present invention has convergence, and will not cause instability due to the time difference between the sound wave signal and the electric signal. This logic control part is mainly to solve the problem of the electroacoustic sensor 5 and the The problem of the time difference formed by the relative position distance of the loudspeaker 4, because the noise signal 22 is composed of sound waves of different frequencies, with a single frequency sound wave analysis, it is assumed that the sound wave signal is P1, the anti-phase sound wave signal is P2, and the two sound wave signals The resulting time difference is dt=dL/v, dL is the relative distance difference between the electroacoustic sensor 5 and the loudspeaker 4, v is the sound wave velocity, and the signal produced by the sound wave interference is dP, and its relative relationship is as follows Show:

P1＝Sin(w t+dt)

P2＝Sin(w t+π)

dt=dL/v

dP=P1+P2………(Formula 2)

It can be seen from formula 2 that the time difference caused by the relative distance difference between the electroacoustic sensor 5 and the loudspeaker 4 affects the amplitude after the interference, while the frequency w has no effect on the interference. In other words, the present invention The anti-noise logic system adopted is not affected by different frequencies, and the frequency parameters mentioned can be ignored.

It can be seen from the above that the present invention can eliminate the high noise that cannot be eliminated by the general traditional noise suppression circuit through the design of the acoustic filter structure formed by the outer conduit 1, the cavity 2, the inner conduit 3, the electroacoustic sensor 5 and the speaker 4. High-frequency noise signal, as for low-frequency noise signal, it can be eliminated by suppressing circuit design; please refer to Figure 3 again, verified by actual design:

The cross-sectional area S1 of the outer catheter 1 is less than 100mm2, and the length L1 is less than 30mm;

The cross-sectional area S2 of the cavity 2 is less than 500mm2, and the length L2 is less than 20mm;

The cross-sectional area S1 of the inner conduit 3 is less than 100mm2, and the length L1 is less than 30mm;

When the cross-sectional area S1=S2=S3, the frequency spectrum generated by the sound wave signal passing through the cavity 2 is shown in Figure 6, which shows that the sound wave penetration energy is not attenuated; when the cross-sectional area S1=S3=3.142mm2, S2=314.2mm2 , the frequency spectrum generated by the sound wave signal passing through the cavity 2 is shown in Figure 7, which shows that the sound penetration energy in the high frequency region will be attenuated. In other words, the cross-sectional area S2 of the cavity 2 must be larger than the outer conduit 1 and the cross-sectional areas S1 and S3 of the inner conduit 3 .

As shown in Figure 8, the characteristic measurement diagram of suppressing high-frequency noise of the present invention (please refer to Figure 3 at the same time), wherein, the curve A is measured by the electroacoustic sensor 5 (shown in Figure 3) The environmental noise sound wave signal, and the curve B represents the sound wave signal measured in the noise suppression device 10 provided by the present invention, showing that the high frequency noise signal (frequency up to 2KHz) can indeed be canceled by interference.

In summary, the noise suppression method of the present invention can be summarized, which includes the following steps:

providing an outer conduit to allow acoustic signals to enter a cavity;

An electroacoustic sensor receives the noise signal in the cavity and converts it into an electronic signal;

A noise suppression circuit receives the electronic signal generated by the electroacoustic sensor, and generates an anti-phase sound wave signal through the speaker; the anti-phase sound wave signal generated by the speaker and the noise signal in the cavity are in the Interference offset effect occurs in the cavity;

The noise-canceled sound wave signal is sent out of the cavity through an inner conduit.

The noise suppression device and method provided by the present invention combine an active noise suppression circuit and a cavity structure designed with an appropriate size, suppress low-frequency noise through the active noise suppression circuit, and form a low-pass sound field filter through the cavity to Block high-frequency noise, so that the purpose of anti-noise at all frequencies can be achieved.

The above descriptions are only preferred embodiments of the present invention, and are only illustrative rather than restrictive to the present invention. Those skilled in the art understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all will fall within the protection scope of the present invention.

Claims (36)

1. noise-suppressing device, it is characterized in that: it comprises:

One cavity;

The plural number conduit links described cavity, passes in and out described cavity in order to sound signal to be provided;

One noise reducing circuit includes the sound signal of noise signal in order to reception, and produces electric signal;

One electroacoustic transducer in order to receiving the sound signal in the described cavity, and is delivered to described noise reducing circuit after transferring it to electric signal; And

One loud speaker, in order to receive the electric signal that described noise reducing circuit produces and to produce an anti-phase sound signal, the sound signal of described anti-phase sound signal superposition in described cavity, and in described cavity, produce and interfere negative function with noise signal in the described cavity.

2. noise-suppressing device as claimed in claim 1 is characterized in that: the sectional area of described cavity is the sectional area greater than described conduit.

3. noise-suppressing device as claimed in claim 1 is characterized in that: being uneven in length in the length of described conduit of described cavity.

4. noise-suppressing device as claimed in claim 1 is characterized in that: plural conduit comprises:

One outer catheter provides described sound signal to enter the pipeline of described cavity;

One inner catheter will be in order to will send the pipeline of described cavity through the sound signal of noise cancellation.

5. noise-suppressing device as claimed in claim 4 is characterized in that: the sectional area of described outer catheter is different with the sectional area and the length of described inner catheter with length.

6. noise-suppressing device as claimed in claim 1 is characterized in that: described electroacoustic transducer connects a feedback circuit, delivers to described loud speaker by described feedback circuit with sound signal is anti-phase.

7. noise-suppressing device as claimed in claim 1 is characterized in that: also comprise a housing, in order to ccontaining described cavity, conduit, electroacoustic transducer and loud speaker.

8. noise-suppressing device as claimed in claim 7 is characterized in that: described cavity, conduit are one-body molded with described housing.

9. noise-suppressing device as claimed in claim 7 is characterized in that: described housing is sent sound wave into an end of duct at conduit, and its outer earplug structure that is provided with partly leaks into human antrum auris in order to avoid noise by non-device.

10. noise-suppressing device as claimed in claim 7 is characterized in that: described housing has a circuit and connects the hole, in order to described electroacoustic transducer wired connection external circuit to be provided.

11. noise-suppressing device as claimed in claim 7 is characterized in that: described housing has a circuit and connects the hole, in order to described loud speaker wired connection external circuit to be provided.

12. noise-suppressing device as claimed in claim 1 is characterized in that: described electroacoustic transducer and loud speaker are that wired or wireless mode is connected with external circuit.

13. noise-suppressing device as claimed in claim 1 is characterized in that: described electroacoustic transducer is arranged between loud speaker and the external auditory meatus.

14. noise-suppressing device as claimed in claim 1, it is characterized in that: be provided with a perforate between described electroacoustic transducer and the described cavity, in order to provide described electroacoustic transducer to receive sound signal in the described cavity by described perforate, described electroacoustic transducer is vertical to the direction of transfer of cavity with conduit input sound wave by the direction of described perforate reception sound signal.

15. noise-suppressing device as claimed in claim 1 is characterized in that: described inside cavity and described conduit junction are provided with chamfering.

16. noise-suppressing device as claimed in claim 1 is characterized in that: described cavity madial wall is provided with sound-absorbing material.

17. noise-suppressing device as claimed in claim 1 is characterized in that: the relative inner wall of described cavity is not parallel each other.

18. noise-suppressing device as claimed in claim 1 is characterized in that: described cavity is rule or irregularly shaped arbitrarily.

19. noise-suppressing device as claimed in claim 1 is characterized in that: described conduit is rule or irregularly shaped arbitrarily.

20. a noise suppression method is characterized in that: its step that comprises is:

Provide an outer catheter to make sound signal enter a cavity;

Receive noise signal in the described cavity by an electroacoustic transducer, and transfer it to electric signal;

Receive the electric signal that described electroacoustic transducer produces by a noise reducing circuit, produce an anti-phase sound signal via loud speaker; Anti-phase sound signal that described loud speaker produces and the noise signal in the described cavity produce in described cavity interferes negative function;

To send described cavity through the sound signal of noise cancellation by an inner catheter.

21. noise suppression method as claimed in claim 20 is characterized in that: the sectional area of described cavity is the sectional area greater than inside and outside conduit, and when described sound signal entered described cavity, the high-frequency signals of described sound signal was suppressed.

22. noise suppression method as claimed in claim 20 is characterized in that: the sectional area of described outer catheter is different with the sectional area and the length of described inner catheter with length.

23. noise suppression method as claimed in claim 20 is characterized in that: described noise reducing circuit is to comprise a feedback circuit, by described feedback circuit electric signal is delivered to described loud speaker, makes it produce anti-phase sound signal.

24. a noise-suppressing device, it is characterized in that: it comprises:

One cavity;

The plural number conduit links described cavity, passes in and out described cavity in order to the sound signal that includes the noise signal to be provided;

Low pass acoustic wave filter by described conduit and cavity form suppresses the high frequency noise signal in the described sound signal.

25. noise-suppressing device as claimed in claim 24 is characterized in that: the sectional area of described cavity is greater than the sectional area of described conduit.

26. noise-suppressing device as claimed in claim 24 is characterized in that: being uneven in length of described cavity in the length of described conduit.

27. noise-suppressing device as claimed in claim 24 is characterized in that: plural conduit comprises:

One outer catheter provides described sound signal to enter the pipeline of described cavity;

One inner catheter will be in order to will send the pipeline of described cavity through the sound signal of noise cancellation.

28. noise-suppressing device as claimed in claim 27 is characterized in that: the sectional area of described outer catheter is different with the sectional area and the length of described inner catheter with length.

29. noise-suppressing device as claimed in claim 24 is characterized in that: also comprise a housing, in order to ccontaining described cavity and conduit.

30. noise-suppressing device as claimed in claim 29 is characterized in that: described cavity, conduit are one-body molded with described housing.

31. noise-suppressing device as claimed in claim 29 is characterized in that: described housing is sent sound wave into an end of duct at conduit, and its outer earplug structure that is provided with partly leaks into human antrum auris in order to avoid noise by non-device.

32. noise-suppressing device as claimed in claim 24 is characterized in that: described inside cavity and described conduit junction are provided with chamfering.

33. noise-suppressing device as claimed in claim 24 is characterized in that: described cavity madial wall is provided with sound-absorbing material.

34. noise-suppressing device as claimed in claim 24 is characterized in that: the relative inner wall of described cavity is not parallel each other.

35. noise-suppressing device as claimed in claim 24 is characterized in that: described cavity is rule or irregularly shaped arbitrarily.

36. noise-suppressing device as claimed in claim 24 is characterized in that: described conduit is rule or irregularly shaped arbitrarily.

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