KR20230048471A - Contact free Noise Cancelling Headphone - Google Patents

Abstract

Provided is a non-contact noise-canceling headphone to eliminate noise entering an open space from the outside. According to the present invention, the headphones comprises: a first microphone and third microphone disposed outside when the headphone are worn and receiving primary noise signals contaminated by feedback signals and feedback interference signals; a first processing unit and fourth processing unit removing the feedback signal and feedback interference signal from the contaminated signal and controlling the filter characteristics, phase, and amplitude of the extracted primary noise signal for each frequency band to generate and output an anti-phase noise control signal to a speaker; a second microphone and fourth microphone disposed inside when the headphone is worn and receiving the residual noise signal contaminated by interference signals; a third processing unit and sixth processing unit removing the interference signal from the contaminated signal and transmitting the extracted residual noise signal to a main controller; and the main controller generating and transmitting a control signal, which controls the filter characteristics, phase, and amplitude for each frequency band to minimize the energy level of the residual noise signal, to the first processing unit and the fourth processing unit. Accordingly, noise flowing into a noise-removing space existing between the headphone worn in a non-contact manner and the ear can be effectively eliminated.

Description

Contact free noise canceling headphone {Contact free Noise Canceling Headphone}

The present invention relates to a headphone device having a noise canceling function and a noise canceling method applied thereto, and more particularly, to a non-contact type headphone that does not adhere to the ear, in which noise generated in the surrounding environment is transmitted to the ear through air as a medium In this case, it relates to a noise canceling method for generating an anti-phase noise control signal based on a noise signal input through a microphone so that these noises can be mutually eliminated, and a headphone device having this function implemented.

Various technologies capable of outputting sound while reducing the influence of noise generated in the surrounding environment are being developed. This noise canceling technology is applied to sound output devices such as earphones or headphones, and it is a big task to effectively remove noise introduced from the outside and at the same time minimize the loss of sound generated during the noise canceling process.

Conventional noise removal technology creates an anti-phase noise control signal (anti-noise) that is 180 degrees out of phase with the noise signal to be removed and has the same size, and superimposes it on the original noise signal to reduce noise. This is called Active Noise Control (ANC) technology.

General noise canceling headphones with active noise control technology are worn closely to the ears, and the noise signal, which is the basic signal for generating anti-phase noise control signals, receives the noise propagated in the air, but passes through the headphone device to Noise introduced into the ear has differences in frequency response characteristics, phase, amplitude, etc., and the noise introduced into the ear is removed by compensating for the difference.

Most of the noise canceling earphones or headphones using this method are worn closely to the ears, so they must be sealed so that the sound does not leak out to perform properly, and when the degree of sealing is weak, the noise canceling performance drops sharply is holding

In addition, by wearing earphones or headphones in close contact, air flow is blocked, causing various otolaryngological diseases, and in addition, it is difficult to recognize external acoustic situations, causing safety problems.

The present invention is to solve the problems of the prior art, and an object of the present invention is to provide a method of reducing the influence of ambient noise input to headphones in a non-contact wearing state that are not worn close to the ears.

Headphones for achieving the object of the present invention described above are located outside when the headphones are worn, and primary noise propagated from a noise source through air as a medium, a feedback signal, and a feedback interference signal are added to the primary noise. a first microphone that receives an input signal; The first input signal removes the feedback signal and the feedback interference signal, separates the extracted noise signal for each frequency band, controls the characteristics, phase, and amplitude of the filter, and outputs the anti-phase noise control signal to the speaker. 1 processing unit; A first speaker located inside when headphones are worn and outputting the antiphase noise control signal to the air; A second microphone that is located inside when wearing headphones and receives a secondary input signal in which an antiphase noise control signal output to the first speaker and an interference signal are added to the secondary noise propagated from the noise source through air as a medium; a third processing unit for removing an interference signal from a residual noise signal remaining after part of the secondary noise is eliminated by the antiphase noise control signal, converting the extracted residual noise signal into a digital signal, and transmitting the digital signal to a main controller; and a second processing unit that converts the primary input signal input into the first microphone into a digital signal and transmits the digital signal to a main controller.

Headphones for achieving the above object of the present invention analyze signals input through the first microphone, the second microphone, the third microphone, and the fourth microphone, and a first noise extractor, a second noise extractor, and a multi-band active It includes a main controller that generates and transmits various control signals necessary for the unique operation of the noise control block.

Headphones for achieving the object of the present invention described above are located outside when the headphones are worn and receive a tertiary input signal in which a feedback signal and an interference signal are added to tertiary noise propagating from a noise source through air as a medium a third microphone; A fourth processing unit that removes the feedback signal and the interference signal from the tertiary input signal, separates the noise signal extracted by frequency band, controls the characteristics, phase, and amplitude of the filter, and outputs an anti-phase noise control signal to a speaker; a second speaker located inside when the headphones are worn and outputting the anti-phase noise control signal to the air; A fourth microphone that is located inside when headphones are worn and receives a fourth input signal in which an antiphase noise control signal output to a second speaker and an interference signal are added to the fourth noise propagated from a noise source through air as a medium; a sixth processing unit for converting a residual noise signal extracted by removing an interference signal from a residual noise signal remaining after a portion of the fourth-order noise is eliminated by the anti-phase noise control signal, and transmitting the digital signal to a main controller; and a fifth processing unit that converts the tertiary input signal input into the third micro into a digital signal and transmits it to a main controller.

The first processing unit and the fourth processing unit for achieving the object of the present invention described above remove a feedback signal and a feedback interference signal from among the primary input signal and the tertiary input signal input to the first microphone and the third microphone, a primary noise extractor for extracting original primary noise and tertiary noise; and a multi-band active noise control block that separates the noise signal extracted through the primary noise extractor into a plurality of frequency bands and controls the characteristics, phase, and amplitude of the filter for each frequency band to generate an anti-phase noise control signal. includes

A primary noise extractor for achieving the above object of the present invention includes a filter controlled by a main controller to compensate for a change in a signal caused by a transmission process on each transmission path of a feedback signal and a feedback interference signal; and a phase controller; and an amplitude controller; and a third synthesizer; and a fourth synthesizer.

A multi-band active noise control block for achieving the above object of the present invention includes a filter bank for passing noise signals divided into a plurality of frequency bands under the control of a main controller; and a phase controller controlling the phase of the noise signal divided by frequency band. and an amplitude controller controlling amplitudes of noise signals divided by frequency bands. and a fifth synthesizer; and a sixth synthesizer.

The third processing unit and the sixth processing unit for achieving the above object of the present invention remove interference signals from the secondary input signal and the quaternary input signal input to the second and fourth microphones, It includes a secondary noise extractor that extracts noise and 4th noise.

A secondary noise extractor for achieving the above object of the present invention includes a filter controlled by a main controller to compensate for a change in a signal caused by a transmission process of an interference signal on a transmission path; and a phase controller; and an amplitude controller; and a seventh synthesizer; and an eighth synthesizer.

In order to achieve the above object of the present invention, a method for canceling noise of headphones is a sound transmission path from a first speaker and a second speaker to a first microphone, a second microphone, a third microphone, and a fourth microphone when wearing headphones. The process of estimating the transfer characteristics of by the main controller; receiving a noise signal from the noise source through respective transmission paths to the first microphone, the second microphone, the third microphone, and the fourth microphone; removing a disturbing signal from the contaminated signal by combining a plurality of signals input through the first and third microphones by the main controller and extracting an original noise signal; Separating the noise signal extracted through the primary noise extractor for each frequency band by the main controller and controlling each filter characteristic, amplitude and phase to generate an anti-phase noise control signal; removing noise by overlapping the noise signal introduced from the noise source with the anti-phase noise control signal output to the first speaker and the second speaker; receiving, by the anti-phase noise control signal, a residual noise signal remaining after a part of the noise signal is extinguished by the second microphone and the fourth microphone; removing an interference signal from a signal contaminated by combining a plurality of signals input through the second and fourth microphones by the main controller and extracting an original residual noise signal; and repeatedly controlling, by the main controller, the multi-band active noise control block so that the energy level of the residual noise signal becomes a minimum value.

According to an embodiment of the present invention, noises generated in the surrounding environment can be mutually canceled without the headphones being closely attached to the ears.

According to an embodiment of the present invention, when noise generated in the surrounding environment is input through the microphone through different paths, noises synthesized through different paths can be mutually canceled.

According to an embodiment of the present invention, noises input through different paths can be mutually canceled in a wide frequency band.

1 is a conceptual diagram of a noise canceling headphone that removes noise by forming a noise canceling space in a non-contact state according to an embodiment of the present invention.
2 illustrates transfer functions and respective signals for each propagation path through which various disturbance signals including noise signals propagate according to an embodiment of the present invention.
3 is a block diagram of a processing circuit for removing noise in a noise canceling space in a headphone having a microphone and a speaker for removing noise in a non-contact state according to an embodiment of the present invention.
Figure 4 illustrates the definition and flow of mutually communicated signals on a block diagram of a processing circuit in accordance with one embodiment of the present invention.
5 shows a detailed configuration diagram of a left channel primary noise extractor according to an embodiment of the present invention.
6 shows a detailed configuration diagram of a right channel primary noise extractor according to an embodiment of the present invention.
7 shows a detailed configuration diagram of a left channel multi-band active noise control block according to an embodiment of the present invention.
8 illustrates a detailed configuration diagram of a right channel multi-band active noise control block according to an embodiment of the present invention.
9 shows a detailed configuration diagram of a left channel secondary noise extractor according to an embodiment of the present invention.
10 is a detailed configuration diagram of a right channel secondary noise extractor according to an embodiment of the present invention.
11 illustrates an example of an fx-LMS algorithm including a feedback neutralization filter for implementation in the digital domain of a left channel full system according to an embodiment of the present invention.
12 illustrates an example of an fx-LMS algorithm including a feedback neutralization filter for implementation in the digital domain of a right channel full system according to an embodiment of the present invention.
13 illustrates an example of an operating process of the entire left channel system according to an embodiment of the present invention.
14 shows transfer characteristics of respective sound transmission paths from the first and second speakers to the first and second microphones, and to the third and fourth microphones in the initialization process of the system according to an embodiment of the present invention. An example of the estimation process is shown.
15 illustrates an example of a process of extracting a primary noise signal from a contaminated signal input to a left channel primary noise extractor according to an embodiment of the present invention.
16 illustrates an example of a process of generating an antiphase noise control signal in a left channel multi-band active noise control block according to an embodiment of the present invention.
17 illustrates an example of a detailed process of controlling filter characteristics of a multi-band active noise control block according to an embodiment of the present invention.
18 illustrates an example of a detailed process of controlling the phase of a left channel multi-band active noise control block according to an embodiment of the present invention.
19 illustrates an example of a detailed process of controlling the amplitude of a left channel multi-band active noise control block according to an embodiment of the present invention.
20 illustrates an example of a process of extracting a residual noise signal from a contaminated signal input to a left channel secondary noise extractor according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, numbers (eg, first, second, etc.) used in the description process of this specification are only identifiers for distinguishing one component from another component.

In addition, in this specification, when one component is referred to as “connected” or “connected” to another component, the one component may be directly connected or directly connected to the other component, but in particular Unless otherwise described, it should be understood that they may be connected or connected via another component in the middle.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a conceptual diagram of a noise canceling headphone that removes noise by forming a noise canceling space in a non-contact state according to an embodiment of the present invention, wherein the headphone has a shape that does not directly touch the ear, and the open space between the ear and the headphone As a noise free zone, it becomes a space that removes noise from the external environment.

The non-contact noise canceling headphone includes a first microphone 200, a second microphone 220, a third microphone 300, a fourth microphone 320, a first speaker 210, and a second speaker 310. .

Noise cancellation technology based on feed forward active noise control technology requires a reference microphone to acquire an external noise signal (primary noise), which must be placed outside the left and right channels, respectively, The first microphone 200 and the third microphone 300 are reference microphones for each of the left and right channels.

In addition, an anti-phase noise control signal (anti-noise) for noise removal is output to the noise removal space through the speaker, and the first speaker 210 and the second speaker 310 are inside the left and right channels. are placed in each

In addition, the noise signal and the antiphase noise control signal are overlapped in the noise removal space, and an error microphone is required to acquire the remaining noise signal after the noise is removed, which must be disposed inside the left and right channels, respectively. The second microphone 220 and the fourth microphone 320 are error microphones for each of the left and right channels.

Therefore, in the present invention, the first microphone 200, the third microphone 300, the second microphone 220, and the fourth microphone 320 are provided, and the second microphone 220 and the fourth microphone 320 are provided. ) Only a headphone having a general structure in which a processing circuit for mutually canceling the influence of ambient noise is disposed at an arbitrary point in the vicinity will be described.

In addition, when the operation of each component of the left and right channels is the same, only the left channel will be described, and when signals are disturbed between the left and right channels, both the left and right channels will be described for clarity of the relationship.

Meanwhile, the headphones of FIG. 1 are exemplified in a form mounted on a helmet, but are not limited thereto, and may be implemented as various types of headphones, of course.

The first microphone 200 is disposed at a position exposed to the outside of the headphone when the headphone is worn, receives external noise (primary noise) generated from the noise source 100, and is reversed by a processing circuit to be described later. It is used to generate a phase noise control signal, and the generated anti-phase noise control signal is output through the speaker.

The noise is removed by the anti-phase noise control signal output to the speaker, and the residual noise signal remaining is input to the second microphone 220, and the influence of ambient noise is mutually affected at an arbitrary point around the second microphone 220. Processing circuitry may be arranged to cause removal.

At this time, since the headphones are not worn in close contact with the ears, a sound transmission path using air as a medium is formed between the first microphone 200 and the second microphone 220, so that the input to the first microphone 200 Noise is also input to the second microphone 220 .

Here, since the distances from the noise source 100 to the first microphone 200 and the second microphone 220 are different, and the shape of the space around the first microphone 200 and the second microphone 220 is different, the noise source ( 100) to the first microphone 200 and the second microphone 220 are not the same.

Therefore, the respective noise signals input to the first microphone 200 and the second microphone 220 have a very large correlation (correlation) but are not identical, and the noise signals input to the second microphone 220 is called secondary noise.

The primary noise input through the first microphone 200 may be different from the secondary noise input to the second microphone 220 through different sound transmission paths, and thus, based on the primary noise, The secondary noise is not completely removed by the generated anti-phase noise control signal, and a residual noise signal remains. Hereinafter, a process of processing the residual noise signal will be described in detail with reference to the drawings.

FIG. 2 illustrates transfer functions and respective signals for each transmission path along which a noise signal, a feedback signal, a feedback interference signal, and interference signals propagate according to an embodiment of the present invention. Since general noise canceling headphones are worn closely to the ears, if the antiphase noise control signal is not transmitted from the left and right channel speakers to the reference microphone and error microphone of each left and right channel, or if the size is small enough to be ignored even if it is transmitted is mostly

However, since the headphones according to the embodiment of the present invention are not worn in close contact with the ears, there is air between the first speaker 210, the first microphone 200, the third microphone 300, and the fourth microphone 320. Different sound transmission paths using the medium as a medium are formed, and through these different sound transmission paths, the original primary noise signal and the residual noise signal may be contaminated.

In addition, different sound transmission paths using air as a medium are formed between the first microphone 200, the second microphone 220, and the third microphone 300 from the second speaker 310, and these different sound transmission paths There is a case in which the original primary noise signal and the residual noise signal are contaminated through the path.

As shown in FIG. 2, a transfer function H _L1 (t) exists in the sound transmission path from the noise source 100 to the first microphone 200, and the noise signal Sn(t ) generated from the noise source 100 ) is converted into S _L1 (t) through the transfer function H _L1 (t) and input to the first microphone 200, and assuming that there is no other disturbing signal contaminating S _L1 (t) , S _L1 (t ) = H _L1 (t) * Sn (t) . Here, * denotes a convolution operator.

A transfer function H _L2 (t) exists in the sound transmission path from the noise source 100 to the second microphone 220, and the noise signal Sn(t) generated from the noise source is transmitted through the transfer function H _L2 (t). It is converted into S _L2 (t) and input to the second microphone 220, and assuming that there is no other disturbing signal contaminating S _L2 (t) , S _L2 (t) = H _L2 (t) * Sn(t) ) is defined as

A transfer function H _L3 (t) exists in the sound transmission path from the first speaker 210 to the second microphone 220, and the left channel antiphase noise control signal S _Lan (t) is transmitted through the first speaker ( 210) is converted into S L3 (t) through the transfer function H _spk (t) and the transfer function H _L3 (t ) _of the sound transmission path and is input to the second microphone 220, which contaminates S _L3 (t). Assuming no other disturbing signals, it is defined as S _L3 (t) = [H _spk (t) * S _Lan (t) ] * H _L3 (t).

The left channel anti-phase noise control signal output from the first speaker 210 is fed back to the first microphone 200 using air as a medium, and the sound from the first speaker 210 to the first microphone 200 A transfer function H _L4 (t) exists in the transfer path. The left channel anti-phase noise control signal S _Lan (t) is converted into S _L4 (t) through the transfer function H _spk (t) of the first speaker 210 and the transfer function H _L4 ( t ) of the sound transfer path, S _L4 (t) = [H _spk (t) * S _Lan ( t) _] * H _L4 (t) ) is defined as The left channel feedback signal S _L4 (t) is input to the first microphone 200 after being added to the first noise S _L1 (t) , and pollutes the first noise S _L1 (t) .

A transfer function H _R1 (t) exists in the sound transmission path from the noise source 100 to the third microphone 300, and the noise signal Sn(t) generated from the noise source 100 is a transfer function H _R1 (t ) is converted into S _R1 (t) and input to the third microphone 300, and assuming that there is no other disturbing signal contaminating S _R1 (t) , S _R1 (t) = H _R1 (t) * It is defined as Sn(t) .

A transfer function H _R2 (t) exists in the sound transmission path from the noise source 100 to the fourth microphone 320, and the noise signal Sn(t) generated from the noise source 100 is a transfer function H _R2 (t ) is converted into S _R2 (t) and input to the fourth microphone 320, and assuming that there is no other disturbing signal contaminating S _R2 (t) , S _R2 (t) = H _R2 (t) * It is defined as Sn(t) .

A transfer function H _R3 (t) exists in the sound transmission path from the second speaker 310 to the fourth microphone 320, and the right channel anti-phase noise control signal S _Ran (t) is transmitted through the second speaker ( 310) is converted to S R3 (t) through the transfer function H _spk (t) and the transfer function H _R3 ( t) of the sound _transfer path and is input to the fourth microphone 320, which pollutes S _R3 (t). Assuming no other disturbing signals, it is defined as S _R3 (t) = [H _spk (t) * S _Ran (t) ] * H _R3 (t).

The right channel anti-phase noise control signal output from the second speaker 310 is fed back to the third microphone 300 using air as a medium, and the sound from the second speaker 310 to the third microphone 300 A transfer function H _R4 (t) exists in the transfer path. The right channel anti-phase noise control signal S _Ran (t) is converted into S _R4 (t) through the transfer function H _spk (t) of the second speaker 310 and the transfer function H _R4 ( t) of the sound transfer path, S _R4 (t ) = [H _spk (t) * S _Ran ( t) _] * H _R4 (t) ) is defined as The right channel feedback signal S _R4 (t) is added to the first noise S _R1 (t) and inputted to the third microphone 300, contaminating the first noise S _R1 (t) .

The left channel anti-phase noise control signal output from the first speaker 210 is also transmitted to the third microphone 300 using air as a medium, and the sound from the first speaker 210 to the third microphone 300 A transfer function H _LR2 (t) exists in the transfer path. The left channel anti-phase noise control signal S _Lan (t) is converted into S _LR2 (t) through the transfer function H _spk (t) of the first speaker 210 and the transfer function H _LR2 ( t ) of the sound transfer path, S _LR2 (t ) = [H _spk (t) * S _Lan ( t) _] * H _LR2 (t) ) is defined as The left channel feedback interference signal S _LR2 (t) is added to the first noise S _R1 (t) and inputted to the third microphone 300, contaminating the first noise S _R1 (t) .

The left channel anti-phase noise control signal output from the first speaker 210 is also transmitted to the fourth microphone 320 using air as a medium, and the sound from the first speaker 210 to the fourth microphone 320 A transfer function H _LR1 (t) exists in the transfer path. The left channel anti-phase noise control signal S _Lan (t) is converted into S LR1 ₍ t) through the transfer function H _spk (t) of the first speaker 210 and the transfer function H _LR1 ( t ) of the sound transfer path, S _LR1 (t ) = [H _spk (t) * S _Lan ( t) _] * H _LR1 (t) ) is defined as The left channel interference signal S _LR1 (t) is added to the secondary noise S _R2 (t) and inputted to the fourth microphone 320, contaminating the residual noise signal S _R2 (t) - S _R3 (t). .

The right channel anti-phase noise control signal output from the second speaker 310 is also transmitted to the first microphone 200 using air as a medium, and the sound from the second speaker 310 to the first microphone 200 A transfer function H _RL2 (t) exists in the transfer path. The right channel anti-phase noise control signal S _Ran (t) is converted into S _RL2 (t) through the transfer function H _spk (t) of the second speaker 310 and the transfer function H _RL2 ( t ) of the sound transfer path, S _RL2 ( t) = [H _spk (t) * S _Ran ( t) _] * H _RL2 (t) ) is defined as The right channel feedback interference signal S _RL2 (t) is added to the primary noise S _L1 (t) and inputted to the first microphone 200, contaminating the primary noise S _L1 (t) .

The right channel anti-phase noise control signal output from the second speaker 310 is also transmitted to the second microphone 220 using air as a medium, and the sound from the second speaker 310 to the second microphone 220 A transfer function H _RL1 (t) exists in the transfer path. The right channel anti-phase noise control signal S _Ran (t) is converted into S _RL1 (t) through the transfer function H _spk (t) of the second speaker 310 and the transfer function H _RL1 ( t ) of the sound transfer path, S _RL1 (t ) = [H _spk (t) * S _Ran ( t) _] * H _RL1 (t) ) is defined as The right channel interference signal S _RL1 (t) is added to the secondary noise S _L2 (t) and inputted to the second microphone 220, contaminating the residual noise signal S _L2 (t) - S _L3 (t). .

The sum of signals S _L1 (t) , S _L4 (t), and S _RL2 (t) input to the first microphone 200 passes through the transfer function H _mic (t) of the first microphone 200 to obtain S _Lref ( t) and transmitted to the left channel active noise control module 2000.

The sum of S _L2 (t) , S _L3 (t) and S _RL1 (t) input to the second microphone 220 is S _Lerr ( t) via the transfer function H _mic (t) of the second microphone 220 ) and transmitted to the left channel active noise control module 2000.

The sum of S _R1 (t) , S _R4 (t) and S _LR2 (t) input to the third microphone 300 passes through the transfer function H _mic (t) of the third microphone 300 to obtain S _Rref (t) ) and transmitted to the right channel active noise control module 3000.

The sum of S _R2 (t) , S _R3 (t), and S _LR1 (t) input to the fourth microphone 320 is S _Rerr (t ) via the transfer function H _mic (t) of the fourth microphone 320 ) and transmitted to the right channel active noise control module 3000.

The left channel anti-phase noise control signal S _Lan (t) is output to the noise removal space through the transfer function H _spk (t) of the first speaker 210, and the right channel anti-phase noise control signal S _Ran (t) is It is output to the noise removal space via the transfer function H _spk (t) of the second speaker 310.

Among the transfer functions of the sound transfer path, H _L4 (t) and H _RL2 (t), H _L3 (t) and H _RL1 (t), H _R4 (t) and H _LR2 (t), H _R3 (t) and H _LR1 (t) must obtain a transfer function estimated in advance by the main controller 1000, and the estimated transfer function H' _L4 (t) and H' _RL2 (t), H' _L3 ( t) and H' _RL1 (t), H' _R4 (t) and H' _LR2 (t), H' _R3 (t) and H' _LR1 (t) are shown in FIG.

The process of obtaining the estimated transfer function must be executed at least once in an off-line state in which the active noise control process is not executed at the beginning of the operation of the non-contact noise canceling headphones according to the embodiment of the present invention, and then, if necessary, active noise control It goes without saying that the process of obtaining the estimated transfer function can be executed even in an online state where the process is being executed.

3 is a block diagram of a processing circuit for removing ambient noise in a headphone having a microphone and a speaker for removing noise in a non-contact state according to an embodiment of the present invention, and FIG. 4 is an embodiment of the present invention. It shows the definition and flow of mutually transmitted signals on the block diagram of the processing circuit according to.

A process of removing a disturbance signal and extracting a first order noise signal from signals input through the first microphone 200 and the third microphone 300 for the left and right channels, respectively, and the second microphone 220 and the fourth microphone From the signal input through 320, only the process of removing the disturbance signal and extracting the residual noise signal is different, and the rest of the operation for removing noise is the same, so the left channel will be described as a reference.

3 and 4, the signal S _Lref (t) input through the first microphone 200 passes through the first processing unit 2100 to generate an anti-phase noise control signal S _Lan (t), It is output through a speaker 210, and the first processing unit 2100 includes a preamplifier Lp 2110, a primary noise extractor L 2120, a multi-band active noise control block L 2150, and a first synthesizer 2180. and power amplifier L 2190.

In addition, the signal S' _Lref (t) output through the preamplifier Lp (2110) is input to the main controller 1000 through the second processing unit 2200, and the second processing unit 2200 is a filter Lp (2210) and an A/D converter Lp 2220.

In addition, the signal S _Lerr (t) input through the second microphone 220 is input to the main controller 1000 through the third processing unit 2300, and the third processing unit 2300 generates a preamplifier Ls 2310 , a secondary noise extractor Ls (2320), a filter Ls (2350) and an A/D converter Ls (2360).

Referring to FIGS. 3 and 4 , the signal S _Lref (t) input through the first microphone 200 is transferred to the first-order noise signal S _L1 (t) through the first speaker 210 at the left side. The feedback signal S _L4 (t) of the channel anti-phase noise control signal and the feedback interference signal S _RL2 (t) of the right channel anti-phase noise control signal transmitted through the second speaker 310 are added to obtain the first microphone 200 ) is the signal transmitted through the transfer function H _mic (t).

The signal S _Lref (t) = H _mic (t) * [ S _L1 (t) + S _L4 (t) + S _RL2 (t) ], wherein the signal S _Lref (t) is preamplifier Lp (2110 ), the amplified signal S' _Lref (t) is input to the primary noise extractor L (2120), and then the S _L4 (t) and S _RL2 (t) components are removed to obtain the primary noise signal S _L1 ( S _Lex1 (t ) corresponding to t) is extracted. A detailed block diagram of extracting S _Lex1 (t) in the primary noise extractor L (2120) is shown in FIG. 5, and a detailed S _Lex1 (t) extraction process is shown in FIG. 15.

The signal S _Lex1 (t) output from the primary noise extractor L (2120) is input to the multi-band active noise control block L (2150) to generate an antiphase noise control signal, which is then input to the first synthesizer (2180). The first synthesizer 2180 synthesizes the anti-phase noise control signal and the audio signal L as necessary, and transmits the amplified signal S _Lan (t) through the power amplifier L 2190 to the first speaker 210. output through A detailed block diagram of the multi-band active noise control block L 2150 is shown in FIG. 7, a process of generating an anti-phase noise control signal is shown in FIG. 16, and a detailed generation process is shown in FIGS. 17, 18, and 19 shown in

The second processor 2200 shown in FIG. 3 converts the signal S′ _Lref (t) generated through the preamplifier Lp 2110 to measure and analyze the signal input through the first microphone 200. It is input to the main controller 1000 through the filter Lp 2210 and the A/D converter Lp 2220.

The analog signal S' _Lref (t) is converted into a digital signal through the A/D converter Lp 2220, and an aliasing phenomenon in which the signal is distorted occurs during the sampling process, which is one of the essential steps of the conversion process. As it happens, the filter Lp 2210 is a low-pass filter that prevents aliasing and is referred to as an anti-aliasing filter.

The third processor 2300 shown in FIG. 3 uses the signal S' _Lerr (t) generated through the preamp Ls 2310 to measure and analyze the signal input through the second microphone 220. It is input to the main controller 1000 through the secondary noise extractor Ls (2320), filter Ls (2350), and A/D converter Ls (2360), where filter Ls (2350) and A / D converter Ls (2360) It performs the same role as the filter Lp 2210 and the A/D converter Lp 2220 of the second processing unit 2200.

Referring to FIGS. 3 and 4 , the signal S _Lerr (t) input through the second microphone 220 corresponds to the secondary noise signal S _L2 (t) at the left output through the first speaker 210. The transfer function of the second microphone 220 is obtained by adding the channel anti-phase noise control signal S _L3 (t) and the interference signal S _RL1 (t) of the right channel anti-phase noise control signal transmitted through the second speaker 310 H This is the signal transmitted through _mic (t).

The signal S _Lerr (t) = H _mic (t) * [ S _L2 (t) - S _L3 (t) + S _RL1 (t) ], the anti-phase noise control signal S _L3 (t) is 2 Since the difference noise signal S _L2 (t) is in opposite phase, the two signals are overlapped and mutually canceled in the noise removal space, and only the residual noise signal that has not been removed remains, and the anti-phase noise control signal S _L3 (t ) is of the opposite phase to the secondary noise signal S _L2 (t) , so the residual noise signal can be expressed as S _L2 (t) - S _L3 (t) .

Therefore, S _Lerr (t) is a signal obtained by adding the right channel interference signal S _RL1 (t) to the residual noise signal, and the signal S' _Lerr (t) amplified through the preamplifier Ls 2310 is the second noise extractor Ls After being input to 2320, the S _RL1 ( t) _component is removed and S _Lex2 (t) corresponding to the residual noise signal S L2 (t) - S _L3 (t) is extracted.

The extracted residual noise signal S _Lex2 (t) is input to the main controller 1000 through the filter Ls 2350 and the A/D converter Ls 2360, and the main controller 1000 receives the residual noise signal S _Lex2 ( t) continuously controls the primary noise extractor L 2120 and the multi-band active noise control block L 2150 of the first processing unit 2100 so that the energy level becomes a minimum value, thereby optimizing noise removal performance. A detailed block diagram of extracting S _Lex2 (t) in the secondary noise extractor Ls (2320) is shown in FIG. 9, and a detailed process of extracting S _Lex2 (t) is shown in FIG. 20.

5 shows a detailed configuration diagram of a left channel primary noise extractor L 2120 according to an embodiment of the present invention. The signal S _Lref (t) input through the first microphone 200 is a feedback signal S _L4 (t) of the left channel anti-phase noise control signal output from the first speaker 210, and the second speaker Since the first noise signal S L1 (t ) is contaminated by the feedback interference signal S _RL2 (t) of the right channel anti- _phase noise control signal output from 310, the two disturbance signals that pollute S _L1 ( t ) must be removed, and this role is performed by the primary noise extractor L (2120).

1st order noise signal S _L1 (t) extracted by removing two disturbing signals ?? It can be defined as S' _Lref (t) - S _L4 (t) - S _RL2 (t) , and S _Lref (t) amplified through the preamplifier Lp (2110) is converted into S' _Lref (t) It is input to the primary noise extractor L (2120).

In addition _, the left channel feedback signal S L4 (t) transmitted through the transfer function H _L4 ( t ) from the first speaker 210 to the first microphone 200 is the left channel anti-phase noise control signal S _Lan (t ) is derived from; It is shown by a red dotted line in FIG. 4, and S _L4 (t) is simulated through the filter Le1 (2130), the phase controller Le1 (2132), and the amplitude controller Le1 (2134) included in the primary noise extractor L (2120). Create S' _L4 (t) .

Here, the filter Le1 (2130), the phase controller Le1 (2132), and the amplitude controller Le1 (2134) serve to simulate the estimated transfer function H' _L4 (t), and in detail, the filter Le1 (2130) causes the The main controller 1000 controls the filter characteristics to simulate the frequency response characteristics of the estimated transfer function H' _L4 (t), and the phase controller Le1 2132 causes the phase response of the estimated transfer function H' _L4 (t) The phase is controlled by the main controller 1000 to simulate the characteristic, and the amplitude is controlled by the main controller 1000 so that the amplitude controller Le1 (2134) simulates the amplitude response characteristic of the transfer function H' _L4 (t). .

Therefore, the main controller 1000 corresponds to the frequency response characteristics, phase response characteristics, and amplitude response characteristics obtained in the process of obtaining the estimated transfer function H' _L4 (t) before the signal S' _L4 (t) generation process A filter control signal for controlling the filter characteristics of the filter Le1 (2130), a phase control signal for controlling the phase of the phase controller Le1 (2132), and an amplitude for controlling the amplitude of the amplitude controller Le1 (2134). A control signal must be transmitted to the primary noise extractor L (2120).

In addition, the right channel feedback interference signal S _RL2 (t) transmitted through the transfer function H _RL2 ( t ) from the second speaker 310 to the first microphone 200 is the right channel anti-phase noise control signal S _Ran ( t) is derived from; It is shown by a red dashed line in FIG. 4, and through the filter Le2 (2140), the phase controller Le2 (2142), and the amplitude controller Le2 (2144) included in the primary noise extractor L (2120), S _RL2 (t) is simulated S' Generate _RL2 (t) .

Here, the filter Le2 (2140), the phase controller Le2 (2142), and the amplitude controller Le2 (2144) serve to simulate the estimated transfer function H' _RL2 (t), and in detail, the filter Le2 (2140) causes the The main controller 1000 controls the filter characteristics to simulate the frequency response characteristics of the estimated transfer function H' _RL2 (t), and the phase controller Le2 2142 controls the phase response of the estimated transfer function H' _RL2 (t) The phase is controlled by the main controller 1000 to simulate the characteristic, and the amplitude is controlled by the main controller 1000 so that the amplitude controller Le2 (2144) simulates the amplitude response characteristic of the transfer function H' _RL2 (t). .

Therefore, the main controller 1000 corresponds to the frequency response characteristics, phase response characteristics, and amplitude response characteristics obtained in the process of obtaining the estimated transfer function H' _RL2 (t) before the signal S' _RL2 (t) generation process A filter control signal for controlling the filter characteristics of the filter Le2 (2140) and a phase control signal for controlling the phase of the phase controller Le2 (2142) and the amplitude of the amplitude controller Le2 (2144) An amplitude control signal for this must be transmitted to the primary noise extractor L (2120).

The three signals S' _Lref (t) , S' _L4 (t), and S' _RL2 (t) are input to the third synthesizer 2122 included in the primary noise extractor L 2120, and the third synthesizer The signal output through 2122 is defined as S _Lex1 (t) = S' _Lref (t) - S' _L4 (t) - S' _RL2 (t) , and S _Lex1 (t) ?? S _L1 (t) , and a detailed process thereof is shown in FIG. 15 .

6 shows a detailed configuration diagram of the right channel primary noise extractor R 3120 according to an embodiment of the present invention, and the process is the same as that of the left channel primary noise extractor L 2120.

7 shows a detailed configuration diagram of a left channel multi-band active noise control block L 2150 according to an embodiment of the present invention. The multi-band active noise control block L 2150 includes n filters Lf1 and Lf2 , ... , filter bank 2155 consisting of Lfn; and a phase controller 2160 composed of n phase control elements Lpc1, Lpc2, ..., Lpcn; and an amplitude controller 2165 composed of n amplitude control elements Lgc1, Lgc2, ..., Lgcn; and a fifth synthesizer 2170, where the subscript n denotes the number of frequency bands.

The filter bank 2155 separates the noise signal S _Lex1 (t) into a plurality of frequency bands based on the band selection control signal of the main controller 1000. Since the primary noise is overlapped by a plurality of noise sources and exhibits a broadband characteristic, an antiphase noise control signal optimized for noise cancellation in a specific frequency band is used for noise cancellation in other frequency bands. It's not optimized. In particular, in a high-frequency band of 1 KHz or higher, errors that increase noise may be generated.

Therefore, the filter bank 2155 subdivides the entire frequency band into a plurality of frequency bands and generates the primary noise in the main controller 1000 for optimized filter characteristics and phase and amplitude control for each frequency band Based on the transmitted control signal, a plurality of frequency bands are separated. To this end, the filter bank 2155 is composed of low-pass filters and band-pass filters of first to n-th frequency bands, and sequentially from the first filter to the n-th filter based on the control signal of the main controller 1000. can be selected as

The signal S _Lex1 (t) output from the first noise extractor L (2120) is very similar to the first noise signal S _L1 (t) , and has an anti-phase of the left channel using the noise signal S _Lex1 (t). Generates a noise control signal.

The filter bank 2155, the phase controller 2160, and the amplitude controller 2165 included in the multi-band active noise control block L 2150 have respective filter characteristics and phases for each frequency band by the main controller 1000. and controlling an amplitude to generate the anti-phase noise control signal, and the anti-phase noise control signal generated for each frequency band passes through the fifth synthesizer 2170 to generate a left channel anti-phase noise control signal over all frequency bands. synthesize

A detailed process of the left channel multi-band active noise control block L 2150 according to an embodiment of the present invention is shown in FIG. 16, and the filter bank 2155 included in the multi-band active noise control block L 2150 When the first order noise signal S _Lex1 (t) is input to , the main controller 1000 selects a filter Lf1 of the first frequency band.

After controlling the response characteristics of the filter of the selected frequency band by the main controller 1000 and controlling the phase of the phase controller of the selected frequency band by the main controller 1000, the amplitude controller of the selected frequency band The amplitude is controlled by the main controller 1000.

Subsequently, the main controller 1000 selects a filter of the next frequency band, and the response characteristics of the filter, the phase of the phase controller, and the amplitude of the amplitude controller are transmitted to the main controller 1000 for each frequency band up to the last frequency band. It is controlled repeatedly by In this process, the main controller 1000 generates a band selection signal, a filter characteristic control signal, a phase control signal, and an amplitude control signal, and transfers them to the multi-band active noise control block L 2150.

When the frequency band exceeds the last frequency band, antiphase noise control signals generated for each frequency band are synthesized through the fifth synthesizer 2170.

A detailed control process by the main controller 1000 of the filters divided by each frequency band of the filter bank 2155 according to an embodiment of the present invention is shown in FIG. 17, and the frequency selected by the main controller 1000 After the main controller 1000 controls the passband gain of the filter of the band and the cut-off frequency of the selected filter by the main controller 1000, the Q value (quality factor, slope or bandwidth) of the selected filter is controlled by the main controller 1000. It is controlled by the controller 1000. In this process, the main controller 1000 calculates the energy level of the signal S _Lex2 (t) extracted from the signal S _Lerr ( t ) input through the second microphone 220 and adjusts the filter characteristics so that this value becomes the minimum value. Control.

A detailed control process by the main controller 1000 of the phase controller 2160 according to an embodiment of the present invention is shown in FIG. 18, and first, the amplitude controller 2165 of the frequency band selected by the main controller 1000 The amplitude value of is initialized by the main controller 1000, and the phase value of the phase controller 2160 of the frequency band selected by the main controller 1000 is initialized to the minimum phase value by the main controller 1000.

After the signal S _Lerr (t) input through the second microphone 220 is extracted through the secondary noise extractor Ls 2320, the energy level of the signal S _Lex2 (t) is calculated by the main controller 1000. stored, and the phase control signal for increasing the phase value by the main controller 1000 is transferred to the phase controller 2160.

The above process is repeated by the main controller 1000 until the last phase value is reached, and when the last phase value is exceeded, the phase value corresponding to the minimum value among the energy levels stored by the main controller 1000 is analyzed The phase control signal for setting the corresponding phase value is transmitted to the phase controller 2160.

A detailed control process by the main controller 1000 of the amplitude controller 2165 according to an embodiment of the present invention is shown in FIG. 19, and first corresponds to the minimum energy level of the frequency band selected by the main controller 1000. The phase controller 2160 is initialized with a phase value of , and the amplitude controller 2165 of the frequency band selected by the main controller 1000 is initialized with a minimum amplitude value.

After the signal S _Lerr (t) input through the second microphone 220 is extracted through the secondary noise extractor Ls 2320, the energy level of the signal S _Lex2 (t) is calculated by the main controller 1000. The amplitude control signal for increasing the amplitude value by the main controller 1000 is transferred to the amplitude controller 2165.

The above process is repeated by the main controller 1000 until the last amplitude value is reached, and when the last amplitude value is exceeded, the amplitude value corresponding to the minimum value among the energy levels stored by the main controller 1000 is analyzed An amplitude control signal for setting a corresponding amplitude value is transferred to the amplitude controller 2165.

In this way, the left channel multi-band active noise control block L (2150) so that the residual noise signal S _L2 (t) - S _L3 (t) input through the second microphone 220 by the main controller 1000 becomes a minimum value Through a process of dividing and controlling the filter bank 2155, the phase controller 2160, and the amplitude controller 2165 included in , for each frequency band, an optimal anti-phase noise control signal is generated, and a fifth synthesizer 2170 ) through which control is repeatedly executed to synthesize an anti-phase noise control signal to be output to the first speaker 210.

8 shows a detailed configuration diagram of the right channel multi-band active noise control block R 3150 according to an embodiment of the present invention, and the process is the same as that of the left channel multi-band active noise control block L 2150. .

9 shows a detailed configuration diagram of a left channel secondary noise extractor L 2320 according to an embodiment of the present invention, and the residual noise signal S _Lerr (t) input through the second microphone 220 is , by the interference signal S _RL1 (t) of the right channel anti-phase noise control signal output from the second speaker 310, through the secondary noise signal S _L2 (t) and the first speaker 210 Since the output left channel anti-phase noise control signal S _L3 (t) is overlapped and the residual noise signal remaining after being mutually removed is contaminated, the disturbance signal that pollutes the residual noise signal must be removed, and the secondary noise extractor Ls (2320) performs this role.

The residual noise signal extracted by removing the disturbance signal S _L2 (t) - S _L3 (t) = S _Lerr (t) - S _RL1 (t) , which is amplified through the preamplifier Ls (2310 ) _Lerr (t) is converted into S' _Lerr (t) and input to the secondary noise extractor Ls (2320).

Here , the right channel interference signal S RL1 (t) transmitted through _the transfer function H _RL1 (t) from the second speaker 310 to the second microphone 220 is the right channel anti-phase noise control signal S _Ran ( t) is derived from; It is shown by a red dashed line in FIG. 4, and through the filter Lse (2330), the phase controller Lse (2332), and the amplitude controller Lse (2334) included in the secondary noise extractor Ls (2320), mimicking S _RL1 (t) S' Generate _RL1 (t) .

Here, the filter Lse 2330, the phase controller Lse 2332, and the amplitude controller Lse 2334 serve to simulate the estimated transfer function H' _RL1 (t), and in detail, the filter Lse 2330 causes the The main controller 1000 controls the characteristics of the filter to simulate the frequency response characteristics of the estimated transfer function H' _RL1 (t), and the phase controller Lse 2332 controls the phase response of the estimated transfer function H' _RL1 (t) The phase is controlled by the main controller 1000 to simulate the characteristic, and the amplitude is controlled by the main controller 1000 so that the amplitude controller Lse 2334 simulates the amplitude response characteristic of the transfer function H' _RL1 (t). .

Therefore, the main controller 1000 corresponds to the frequency response characteristics, phase response characteristics, and amplitude response characteristics obtained in the process of obtaining the estimated transfer function H' _RL1 (t) before the signal S' _RL1 (t) generation process A filter control signal for controlling the filter characteristics of the filter Lse 2330, a phase control signal for controlling the phase of the phase controller Lse 2332, and an amplitude for controlling the amplitude of the amplitude controller Lse 2334. A control signal must be transmitted to the secondary noise extractor L (2320).

The two signals S' _Lerr (t) and S' _RL1 (t) are input to the seventh synthesizer 2340 included in the secondary noise extractor Ls 2320, and the signal S output through the seventh synthesizer 2340 It is defined as _Lex2 (t) = S' _Lerr (t) - S' _RL1 (t) , and S _Lex2 (t) ?? S _L2 (t) - S _L3 (t) , and a detailed process thereof is shown in FIG. 20 .

10 shows a detailed configuration diagram of the right channel secondary noise extractor Rs 3320 according to an embodiment of the present invention, and the process is the same as that of the left channel secondary noise extractor Ls 2320.

11 and 12 show an example of an fx-LMS algorithm including a feedback neutralization filter for implementation in the digital domain of the entire left and right channel system according to an embodiment of the present invention, H^ _L4 (z) and Z ^-1 are feedback neutralization filters, of which H^ _L4 (z) is the transfer function of the feedback sound transfer path from the first speaker 210 to the first microphone 200, H _L4 (z ) is the estimated transfer function of

H ^ _LR1 (z) is an estimated transfer function of the transfer function H _LR1 (z) of the sound transfer path from the first speaker 210 to the fourth microphone 320, and is the left channel interference signal of the right channel error microphone Polluting the input signal.

H ^ _LR2 (z) is an estimated transfer function of the transfer function H _LR2 (z) of the sound transfer path from the first speaker 210 to the third microphone 300, and the right channel reference microphone as the left channel feedback interference signal pollutes the input signal of

13 illustrates an example of an operating process of the entire system of the left channel according to an embodiment of the present invention, in which a signal S _Lref (t) input through the first microphone 200 is transmitted to a preamplifier Lp 2110. After amplification through and amplification, the main controller 1000 extracts S _Lex1 (t) from which the disturbance signal has been removed through the primary noise extractor L (2120), and the main controller 1000 extracts S _Lex1 (t) After generating an anti-phase noise control signal by controlling the filter characteristics, phase, and amplitude for each frequency band of the multi-band active noise control block L (2150), the first synthesizer (2180) and the power amplifier L (2190) Through this, S _Lan (t) is output to the first speaker 210.

The noise signal S _L2 (t) introduced from the noise source 100 and the anti-phase noise control signal S _L3 (t) output to the first speaker 210 are overlapped in the noise removal space, mutually canceled, and the residual noise signal remains. The right channel interference signal S _RL1 (t) is added to the residual noise signal, inputted to the second microphone 220, and amplified through the preamplifier Ls 2310, and then transmitted to the main controller 1000. S _Lex2 (t) from which the disturbing signal is removed is extracted through the secondary noise extractor Ls (2320) and input to the main controller 1000 through the filter Ls (2350) and the A/D converter Ls (2360).

The main controller 1000 repeatedly controls filter characteristics, phase values, and amplitude values for each frequency band of the multi-band active noise control block L 2150 so that the energy level of the input signal S _Lex2 (t) is minimized. do.

14 shows the first microphone 200, the second microphone 220 and the third microphone (from the first speaker 210 and the second speaker 310 in the initialization process of the system according to an embodiment of the present invention) 300) and the fourth microphone 320, it shows an example of the process of estimating the transfer characteristics on each sound transfer path, from the first speaker 210 to the first microphone 200. The estimated transfer function H^ _L4 (t) of the transfer function H _L4 (t) is obtained, and then the transfer function H _RL2 (t) of the sound transfer path from the second speaker 310 to the first microphone 200 Obtain the estimated transfer function H^ _RL2 (t) of

Next, an estimated transfer function H^ _L3 (t) of the transfer function H _L3 (t) of the sound transfer path from the first speaker 210 to the second microphone 220 is obtained, and then the second speaker 310 ) to the second microphone 220, an estimated transfer function H _{^ RL1} (t) of the transfer function H _RL1 (t) of the sound transfer path is obtained.

Next, an estimated transfer function H^ _R4 (t) of the transfer function H _R4 (t) of the sound transfer path from the second speaker 310 to the third microphone 300 is obtained, and then the first speaker 210 ) to the third microphone 300, an estimated transfer function H^ _LR2 (t) of the transfer function H _LR2 (t) of the sound transfer path is obtained.

Next, an estimated transfer function H^ _R3 (t) of the transfer function H _R3 (t) of the sound transfer path from the second speaker 310 to the fourth microphone 320 is obtained, and then the first speaker 210 ) to the fourth microphone 320, the estimated transfer function H^ _LR1 (t) of the transfer function H _LR1 (t) of the sound transfer path is obtained.

15 shows that, as described above, in the left channel primary noise extractor L (2120) according to an embodiment of the present invention, the disturbance signal is removed from the signal input through the first microphone 200, and the primary noise extractor L (2120) An example of a process of extracting a noise signal is shown.

16 illustrates an example of a process of generating an anti-phase noise control signal in the left channel multi-band active noise control block L 2150 according to an embodiment of the present invention, and the left channel multi-band active noise control block L The process of generating the left channel anti-phase noise control signal by dividing the characteristics of the filter included in 2150, the phase value of the phase controller, and the amplitude value of the amplitude controller by the main controller 1000 for each frequency band is shown.

In detail, as shown in FIG. 17, among the filter characteristics included in the multi-band active noise control block according to an embodiment of the present invention, the filter so that the magnitude of the residual noise signal input through the error microphone is minimized. The gain, cutoff frequency, and Q value of the passband of are controlled by the main controller.

In addition, as shown in FIG. 18, the left channel multi-band active noise control block L 2150 minimizes the amplitude of the residual noise signal input through the second microphone 220 according to an embodiment of the present invention. The phase of the included phase controller 2160 is controlled by the main controller 1000, and as shown in FIG. 19, the residual noise signal input through the second microphone 220 according to an embodiment of the present invention. The amplitude of the amplitude controller 2165 included in the left channel multi-band active noise control block L 2150 is controlled by the main controller 1000 to minimize the size of .

20 shows that, as described above, in the left channel secondary noise extractor Ls 2320 according to an embodiment of the present invention, a disturbance signal is removed from a signal input through the second microphone 220, and residual noise An example of a process of extracting a signal is shown.

The noise canceling method as described above can be performed by a controller, processor, or firmware that performs a control function in the headphone device, as well as various electronic devices connected to the headphone device or the headphone device. It may be implemented in the form of program instructions that can be executed through various computer means of electronic devices and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the medium may be those specially designed and configured for the present invention or those known and usable to those skilled in computer software. The hardware devices described above may be configured to act as one or more software modules to perform the operations of the present invention, and vice versa.

The above description of the present invention is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be.

Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be construed as being included in the scope of the present invention. do.

H _L1 (t): Transfer function of the noise propagation path from the noise source 100 to the first microphone 200
H _L2 (t): Transfer function of the noise propagation path from the noise source 100 to the second microphone 220
H _L3 (t): Transfer function of the noise propagation path from the first speaker 210 to the second microphone 220
H _L4 (t): Transfer function of the noise propagation path from the first speaker 210 to the first microphone 200
H _RL1 (t): transfer function of the noise propagation path from the second speaker 310 to the second microphone 220
H _RL2 (t): Transfer function of the noise propagation path from the second speaker 310 to the first microphone 200
H' _L3 (t): Estimated transfer function of the noise propagation path from the first speaker 210 to the second microphone 220
H' _L4 (t): Estimated transfer function of the noise propagation path from the first speaker 210 to the first microphone 200
H' _RL1 (t): Estimated transfer function of the noise propagation path from the second speaker 310 to the second microphone 220
H' _RL2 (t): Estimated transfer function of the noise propagation path from the second speaker 310 to the first microphone 200
H _R1 (t): Transfer function of the noise propagation path from the noise source 100 to the third microphone 300
H _R2 (t): Transfer function of the noise propagation path from the noise source 100 to the fourth microphone 320
H _R3 (t): Transfer function of the noise propagation path from the second speaker 310 to the fourth microphone 320
H _R4 (t): Transfer function of the noise propagation path from the second speaker 310 to the third microphone 300
H _LR1 (t): transfer function of the noise propagation path from the first speaker 210 to the fourth microphone 320
H _LR2 (t): transfer function of the noise propagation path from the first speaker 210 to the third microphone 300
H' _R3 (t): Estimated transfer function of the noise propagation path from the second speaker 310 to the fourth microphone 320
H' _R4 (t): Estimated transfer function of the noise propagation path from the second speaker 310 to the third microphone 300
H' _LR1 (t): Estimated transfer function of the noise propagation path from the first speaker 210 to the fourth microphone 320
H' _LR2 (t): Estimated transfer function of the noise propagation path from the first speaker 210 to the third microphone 300
H _mic (t): transfer function of all microphones according to an embodiment of the present invention as transfer functions of the first microphone 200, the second microphone 220, the third microphone 300, and the fourth microphone 320 is assumed to be the same.
H _spk (t): As the transfer function of the first speaker 210 and the second speaker 310, it is assumed that all speakers according to an embodiment of the present invention have the same transfer function.
S _L1 (t) : The first noise signal transmitted through the noise propagation path H _L1 (t) from the noise source 100 to the first microphone 200
S _L2 (t) : Secondary noise signal transmitted through the noise propagation path H _L2 (t) from the noise source 100 to the second microphone 220
S _L3 (t) : anti-phase noise control signal transmitted through the noise propagation path H _L3 (t) from the first speaker 210 to the second microphone 220
S _L4 (t) : Left channel feedback signal transmitted through the noise propagation path H _L4 (t) from the first speaker 210 to the first microphone 200
S _RL1 (t) : Right channel interference signal transmitted through the noise propagation path H _RL1 (t) from the second speaker 310 to the second microphone 220
S _RL2 (t) : Right channel feedback interference signal transmitted through the noise propagation path H _RL2 (t) from the second speaker 310 to the first microphone 200
S _Lref (t) : Contaminated primary noise signal input to the first microphone 200 and transmitted via transmission characteristics H _mic (t) of the first microphone 200
S' _Lref (t) : S _Lref (t) is the first polluted noise signal output through the preamplifier Lp (2110)
S _Lex1 (t) : S' _Lref (t) is the first noise signal extracted through the first noise extractor L (2120)
S _Lerr (t) : Contaminated residual noise signal input to the second microphone 220 and transmitted via transmission characteristics H _mic (t) of the second microphone 220
S' _Lerr (t) : S _lerr (t) is a polluted residual noise signal output through the preamplifier Ls (2310)
S _Lex2 (t) : Residual noise signal extracted from S' _Lerr (t) through the secondary noise extractor Ls (2320)
S _Lan (t) : anti-phase noise control signal output from the power amplifier L (2190) to the first speaker (210)
S' _L4 (t) : S _L4 (t) where S _Lan (t) is output through the filter Le1 (2130) of the primary noise extractor L (2120), the phase controller Le1 (2132) and the amplitude controller Le1 (2134 ) Left channel feedback signal that simulates
S' _RL2 (t) : S _RL2 ( t) where S _Ran (t) is output through the filter Le2 (2140) of the primary noise extractor L (2120), the phase controller Le2 (2142) and the amplitude controller Le2 (2144 ) Right channel feedback interference signal that simulates
S' _RL1 (t) : S _RL1 (t) where S _Ran (t) is output through the filter Lse (2330) of the secondary noise extractor Ls (2320), the phase controller Lse (2332) and the amplitude controller Lse (2334 ) Right channel interference signal that simulates
S _R1 (t) : Noise signal transmitted through the noise propagation path H _R1 (t) from the noise source 100 to the third microphone 300
S _R2 (t) : Noise signal transmitted through the noise propagation path H _R2 (t) from the noise source 100 to the fourth microphone 320
S _R3 (t) : anti-phase noise control signal transmitted through the noise propagation path H _R3 (t) from the second speaker 310 to the fourth microphone 320
S _R4 (t) : Right channel feedback signal transmitted through the noise propagation path H _R4 (t) from the second speaker 310 to the third microphone 300
S _LR1 (t) : Left channel interference signal transmitted through the noise propagation path H _LR1 (t) from the first speaker 210 to the fourth microphone 320
S _LR2 (t) : Left channel feedback interference signal transmitted through the noise propagation path H _LR2 (t) from the first speaker 210 to the third microphone 300
S _Rref (t) : Contaminated primary noise signal input to the third microphone 300 and transmitted through transmission characteristics H _mic (t) of the third microphone 300
S' _Rref (t) : S _Rref (t) is the first polluted noise signal output through the preamplifier Rp (3110)
S _Rex1 (t) : S' _Rref (t) is the first noise signal extracted through the first noise extractor R (3120)
S _Rerr (t) : Contaminated residual noise signal input to the fourth microphone 320 and transmitted through transmission characteristics H _mic (t) of the fourth microphone 320
S' _Rerr (t) : S _Rerr (t) is the contaminated residual noise signal output through the preamplifier Rs (3310)
S _Rex2 (t) : Residual noise signal from _{which S'Rerr} ( t) is extracted through the secondary noise extractor Rs (3320)
S _Ran (t) : anti-phase noise control signal output from the power amplifier R (3190) to the second speaker (310)
S' _R4 (t) : S _R4 (t) where S _Ran (t) is output through the filter Re1 (3130) of the primary noise extractor R (3120), the phase controller Re1 (3132) and the amplitude controller Re1 (3134 ) Right channel feedback signal that simulates
S' _LR2 (t) : S _LR2 (t) where S _Lan (t) is output through the filter Re2 (3140) of the primary noise extractor R (3120), the phase controller Re2 (3142) and the amplitude controller Re2 (3144 ) Left channel feedback interference signal that simulates
S' _LR1 (t) : S _LR1 (t) where S _Lan (t) is output through the filter Rse (3330) of the secondary noise extractor Rs (3320), the phase controller Rse (3332) and the amplitude controller Rse (3334 ) Left channel interference signal that simulates
H _L2 (z): Transfer function of the noise propagation path from the noise source 100 to the left channel second microphone 220
H _L3 (z): transfer function of the secondary path from the left channel first speaker 210 to the second microphone 220
H^ _L3 (z): Estimated transfer function of the second-order path of the left channel
H^ _L4 (z): Estimated transfer function of the feedback path from the left channel first speaker 210 to the first microphone 200
H^ _RL1 (z): Estimated transfer function of the interference path from the right channel second speaker 310 to the left channel second microphone 220
H^ _RL2 (z): Estimated transfer function of the feedback interference path from the second speaker 310 of the right channel to the first microphone 200 of the left channel
H _R2 (z): Transfer function of the noise propagation path from the noise source 100 to the right channel fourth microphone 320
H _R3 (z): transfer function of the secondary path from the right channel second speaker 310 to the fourth microphone 320
H^ _R3 (z): Estimated transfer function of the second-order path of the right channel
H^ _R4 (z): Estimated transfer function of the feedback path from the right channel second speaker 310 to the third microphone 300
H^ _LR1 (z): Estimated transfer function of the interference path from the left channel 1st speaker 210 to the right channel 4th microphone 320
H^ _LR2 (z): Estimated transfer function of the feedback interference path from the left channel first speaker 210 to the right channel third microphone 300
W(z) + LMS: fx-LMS (filtered-x least mean square) algorithm
S _L1 (n) : Left channel reference noise signal input through the microphone
S _L2 (n) : Secondary noise signal transmitted from S _L1 (n) through the noise propagation path H _L2 (z)
S _L3 (n) : anti-phase noise control signal transmitted through the secondary path H _L3 (z)
S' _L4 (n) : A signal for neutralizing the left channel feedback signal contaminating the reference noise signal S _L1 (n)
S _Lerr (n) : Left channel residual noise signal input through the microphone
S _Lan (n) : Left channel anti-phase noise control signal generated by the fx-LMS algorithm
S' _RL1 (n) : A signal for neutralizing the right channel interference signal contaminating the residual noise signal S _Lerr (n)
S' _RL2 (n) : A signal for neutralizing the right channel feedback interference signal contaminating the reference noise signal S _L1 (n)
S _Lex1 (n) : Noise signal obtained by removing disturbance signals from the reference noise signal S _L1 (n)
S' _Lex1 (n) : The noise signal transmitted through the estimated secondary path H^ _L3 (z) of the reference noise signal S _L1 (n)
S _R1 (n) : Right channel reference noise signal input through the microphone
S _R2 (n) : Secondary noise signal transmitted from S _R1 (n) through the noise propagation path H _R2 (z)
S _R3 (n) : anti-phase noise control signal transmitted through the secondary path H _R3 (z)
S' _R4 (n) : A signal for neutralizing the right channel feedback signal contaminating the reference noise signal S _R1 (n)
S _Rerr (n) : Right channel residual noise signal input through the microphone
S _Ran (n) : Right channel anti-phase noise control signal generated by the fx-LMS algorithm
S' _LR1 (n) : A signal for neutralizing the left channel interference signal contaminating the residual noise signal S _Rerr (n)
S' _LR2 (n) : A signal for neutralizing the left channel feedback interference signal contaminating the reference noise signal S _R1 (n)
S _Rex1 (n) : Noise signal obtained by removing disturbing signals from the reference noise signal S _R1 (n)
S' _Rex1 (n) : The noise signal transmitted through the estimated secondary path H^ _R3 (z) of the reference noise signal S _R1 (n)

Claims (10)

For headphones,
First and third microphones that receive a first input signal obtained by adding a feedback signal and a feedback interference signal to the first noise propagated from a noise source through air as a medium, located outside when wearing headphones;
A first processing unit and a fourth processing unit that removes a feedback signal and a feedback interference signal from the primary input signal, controls the characteristics, phase, and amplitude of the filter for each frequency band to generate an anti-phase noise control signal and output it to a speaker. ;
A first speaker and a second speaker located inside when headphones are worn and outputting the anti-phase noise control signal to the air;
A second microphone that is located inside when wearing headphones and receives a second input signal in which an antiphase noise control signal output to the first speaker and an interference signal are added to the second noise propagated from the noise source through air as a medium, and 4th microphone;
a third processing unit and a sixth processing unit for removing an interference signal from a remaining noise signal remaining after a part of the secondary noise is eliminated by the antiphase noise control signal, converting the interference signal into a digital signal, and transmitting the converted digital signal to a main controller;
a second processing unit and a fifth processing unit converting the primary input signal input into the first microphone into a digital signal and transmitting the converted digital signal to a main controller; and
Signals input through the first, second, third, and fourth microphones are analyzed, and various control signals necessary for the unique operation of the first noise extractor, the second noise extractor, and the multi-band active noise control block are generated. Including a main controller that generates and delivers,
headphone.
According to claim 1,
The first processing unit and the fourth processing unit,
a primary noise extractor L for removing a disturbance signal from the contaminated primary input signal and extracting an original noise signal; and
a primary noise extractor R for removing a disturbance signal from the contaminated tertiary input signal and extracting an original noise signal; and
a multi-band active noise control block L generating an anti-phase noise control signal using the primary noise signal; and
Further comprising a multi-band active noise control block R for generating an anti-phase noise control signal using the primary noise signal,
headphone
According to claim 2,
The primary noise extractor L,
a filter Le1 for compensating for a change in frequency response characteristics caused by a transmission process of the feedback signal on a transmission path; and
a phase controller Le1 for compensating for a change in phase response characteristics caused by a transfer process of the feedback signal on the transfer path; and
an amplitude controller Le1 for compensating for a change in amplitude response characteristics caused by a transmission process of the feedback signal on a transmission path; and
a filter Le2 for compensating for a change in frequency response characteristics caused by a transmission process of the feedback interference signal on a transmission path; and
a phase controller Le2 for compensating for a change in phase response characteristics caused by a transmission process of the feedback interference signal on a transmission path; and
an amplitude controller Le2 for compensating for a change in amplitude response characteristics caused by a transmission process of the feedback interference signal on a transmission path; and
And a third synthesizer for removing a feedback signal and a feedback interference signal from a primary input signal input into the first microphone and extracting primary noise.
Primary noise extractor L.
According to claim 2,
The primary noise extractor R,
a filter Re2 for compensating for a change in frequency response characteristics caused by a transmission process on a transmission path of the feedback signal; and
a phase controller Re2 for compensating for a change in phase response characteristics caused by a transfer process of the feedback signal on a transfer path; and
an amplitude controller Re2 for compensating for a change in an amplitude response characteristic caused by a transmission process of the feedback signal on a transmission path; and
a filter Re1 for compensating for a change in frequency response characteristics caused by a transmission process of the feedback interference signal on a transmission path; and
a phase controller Re1 for compensating for a change in phase response characteristics caused by a transmission process of the feedback interference signal on a transmission path; and
an amplitude controller Re1 for compensating for a change in amplitude response characteristics caused by a transmission process of the feedback interference signal on a transmission path; and
And a fourth synthesizer for removing a feedback signal and a feedback interference signal from the primary input signal input into the third microphone and extracting primary noise.
Primary noise extractor R.
According to claim 2,
The multi-band active noise control block L,
A filter bank passing a first order noise signal divided into a plurality of frequency bands; and
a phase controller controlling a phase of a primary noise signal divided into a plurality of frequency bands; and
Amplitude controller for controlling the amplitude of the primary noise signal divided into a plurality of frequency bands; and
A fifth synthesizer for synthesizing an anti-phase noise control signal generated through a filter bank, a phase controller, and an amplitude controller separated into the plurality of frequency bands,
Multi-Band Active Noise Control Block L.
According to claim 2,
The multi-band active noise control block R,
A filter bank passing a first order noise signal divided into a plurality of frequency bands; and
a phase controller controlling a phase of a primary noise signal divided into a plurality of frequency bands; and
Amplitude controller for controlling the amplitude of the primary noise signal divided into a plurality of frequency bands; and
A sixth synthesizer for synthesizing an anti-phase noise control signal generated through a filter bank, a phase controller, and an amplitude controller separated into the plurality of frequency bands,
Multi-Band Active Noise Control Block R.
According to claim 1,
The third processing unit and the sixth processing unit,
a secondary noise extractor Ls for removing a disturbance signal from the contaminated residual noise signal and extracting an original residual noise signal; and
Further comprising a secondary noise extractor Rs for removing a disturbance signal from the contaminated residual noise signal and extracting an original residual noise signal.
headphone
According to claim 7,
The secondary noise extractor Ls,
a filter Lse for compensating for a change in frequency response characteristics caused by a transmission process of the interference signal on a transmission path; and
a phase controller Lse for compensating for a change in phase response characteristics caused by a transmission process of the interference signal on a transmission path; and
an amplitude controller Lse for compensating for a change in amplitude response characteristics caused by a transmission process of the interference signal on a transmission path; and
And a seventh synthesizer for removing an interference signal from a secondary input signal input into the second microphone and extracting a residual noise signal.
Secondary noise extractor Ls.
According to claim 7,
The secondary noise extractor Rs,
a filter Rse for compensating for a change in frequency response characteristics caused by a transmission process of the interference signal on a transmission path; and
a phase controller Rse for compensating for a change in phase response characteristics caused by a transmission process of the interference signal on a transmission path; and
an amplitude controller Rse for compensating for a change in amplitude response characteristics caused by a transmission process of the interference signal on a transmission path; and
And an eighth synthesizer for removing an interference signal from the secondary input signal input into the fourth microphone and extracting a residual noise signal.
Secondary noise extractor Rs.
In the noise canceling method of headphones,
estimating, by a main controller, transfer characteristics of each sound transfer path from the first and second speakers to the first and second microphones, and to the third and fourth microphones when headphones are worn;
receiving a noise signal from a noise source through respective transmission paths to the first microphone, the second microphone, the third microphone, and the fourth microphone;
removing, by a main controller, a disturbance signal from a contaminated signal by combining a plurality of signals input through the first and third microphones, and extracting an original noise signal;
generating an anti-phase noise control signal by dividing the noise signal extracted through the primary noise extractor for each frequency band by a main controller and controlling filter characteristics, amplitude, and phase;
removing noise by overlapping a noise signal introduced from a noise source with an anti-phase noise control signal output to the first and second speakers;
receiving a remaining noise signal after a part of the noise signal is extinguished by the anti-phase noise control signal into the second microphone and the fourth microphone;
removing an interference signal from a contaminated signal by combining a plurality of signals input through the second and fourth microphones by a main controller, and extracting an original residual noise signal;
Including the process of repeatedly controlling the multi-band active noise control block by a main controller so that the energy level of the residual noise signal becomes a minimum value,
How to cancel noise in headphones.

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