Active noise reduction device and active noise reduction system

Abstract

By efficiently utilizing processing resources according to processor usage, maximum noise reduction performance is achieved. [Solution] An active noise reduction device 1 mounted on a control unit equipped with a processor comprises: a noise cancellation output device 22 that outputs a cancellation sound y to cancel out noise d; an error microphone 23 that generates an error signal e based on noise d and cancellation sound y; and a control device 25 that controls the noise cancellation output device 22 based on the error signal e. The control device 25 includes at least one adaptively updatable filter Wn, C^n, H^n and controls the adaptive update process of the filter Wn, C^n, H^n according to the processor utilization X.

Description

[Technical Field]

[0001] The present invention relates to an active noise reduction device and an active noise reduction system. [Background Art]

[0002] Conventionally, active noise reduction devices that reduce noise by causing a canceling sound having a phase opposite to that of noise to interfere with the noise have been known. An active noise reduction device includes: a canceling sound output device (for example, a speaker) that outputs a canceling sound for canceling noise; an error microphone that generates an error signal based on the noise and the canceling sound; and a control device that controls the canceling sound output device based on the error signal. The control device may include an adaptively updatable filter (see Patent Documents 1 and 2). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. Hei 7-28474 [Patent Document 2] Japanese Unexamined Patent Publication No. 2010-70023 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The active noise reduction device as described above may be mounted as one of a plurality of pieces of application software on a control unit including a processor. In such a case, the usage rate of the processor changes in accordance with the operating states of the plurality of pieces of application software, and accordingly, the processing resources (that is, the processing amount of the processor) available to the active noise reduction device also change. Therefore, it is required to achieve maximum noise reduction performance by efficiently utilizing processing resources in accordance with the usage rate of the processor.

[0005] In view of the above background, one aspect of the present invention aims to provide an active noise reduction device and an active noise reduction system that can achieve maximum noise reduction performance by efficiently utilizing processing resources according to the processor usage rate. [Means for solving the problem]

[0006] To solve the above problems, one aspect of the present invention provides an active noise reduction device mounted on a control unit equipped with a processor, comprising: a noise cancellation output device that outputs a cancellation sound for canceling out noise; an error microphone that generates an error signal based on the noise and the cancellation sound; and a control device that controls the noise cancellation output device based on the error signal, wherein the control device includes at least one adaptively updatable filter and controls the adaptive update process of the filter according to the utilization rate of the processor.

[0007] Another aspect of the present invention is an active noise reduction system comprising: an active noise reduction device mounted on the control unit as one of a plurality of application software; and system software mounted on the control unit together with the active noise reduction device, wherein the control device performs the adaptive update process of the filter according to a processing pattern, outputs a processing amount signal relating to the processing amount of the processing pattern to the system software, the system software stores a priority table defining the relationship between the plurality of application software and its priority, and reduces the processing amount of at least one of the plurality of application software based on the processing amount signal and the priority table. [Effects of the Invention]

[0008] According to the above embodiments, it is possible to provide an active noise reduction device and an active noise reduction system that can achieve maximum noise reduction performance by efficiently utilizing processing resources according to the processor usage rate. [Brief explanation of the drawing]

[0009] [Figure 1] Schematic diagram showing a vehicle to which an active noise reduction device according to a first embodiment is applied [Figure 2] Block diagram showing a vehicle to which an active noise reduction device according to a first embodiment is applied [Figure 3] Block diagram showing an active noise reduction device according to a first embodiment [Figure 4] Table showing a pattern table according to a first embodiment [Figure 5] Flowchart showing processing control according to a first embodiment [Figure 6] Block diagram showing an active noise reduction device according to a second embodiment [Figure 7] Table showing a processing amount table according to a second embodiment [Figure 8] Flowchart showing usage rate estimation control according to a second embodiment [Figure 9] Block diagram showing a vehicle to which an active noise reduction device according to a third embodiment is applied [Figure 10] Table showing a processing amount table according to a third embodiment [Figure 11] Block diagram showing an active noise reduction device according to a fourth embodiment [Figure 12] Table showing a pattern readout table according to a fourth embodiment [Figure 13] Flowchart showing processing control according to a fourth embodiment [Figure 14] Table showing a priority table according to a fourth embodiment [Figure 15] Block diagram showing an active noise reduction device according to another embodiment Description of Embodiments

[0010] <<First Embodiment>> Hereinafter, an active noise reduction device 1 according to a first embodiment (hereinafter abbreviated as "noise reduction device 1") will be described with reference to FIGS. 1 to 5. In this specification, the "^" (hat) added to various reference signs indicates an identified value or an estimated value. In drawings and mathematical expressions, "^" is placed above various reference signs, while in the main text, it is placed after various reference signs.

[0011] <Vehicle 3> Figure 1 is a schematic diagram showing a vehicle 3 to which the noise reduction device 1 is applied. The vehicle 3 includes a vehicle body 5, a plurality of wheels (not shown) arranged below the vehicle body 5, and a plurality of suspensions 6 arranged between the vehicle body 5 and the plurality of wheels. A vehicle compartment 8 is formed inside the vehicle body 5. A plurality of occupant seats 9 are installed in the vehicle compartment 8. Each occupant seat 9 includes a seat cushion 9A, a seat back 9B arranged behind and above the seat cushion 9A, and a headrest 9C fixed to the upper end of the seat back 9B.

[0012] Figure 2 is a block diagram showing a vehicle 3 to which the noise reduction device 1 is applied. The vehicle 3 includes an ECU 11 (Electronic Control Unit). The ECU 11 is an example of a control unit. The ECU 11 includes a processor 12 such as a CPU or MPU, and a memory 13 such as a ROM or RAM. When the processor 12 executes a program stored in the memory 13, a plurality of functional units Fm (m=1 to M) of the ECU 11 exert their functions. That is, the plurality of functional units Fm are executed on the processor 12.

[0013] The ECU11 is equipped with several functional units Fm, including an operating system 14 (hereinafter abbreviated as "OS14"), a noise reduction device 1 (more specifically, a control device 25 described later), a 3D audio device 15, a hands-free telephone 16 (hereinafter abbreviated as "HFT16"), an image quality setting device 17 (a device for setting the image quality of videos, etc.), and a background service 18 (a service for background communication, etc.). The OS14 and the noise reduction device 1 constitute an active noise reduction system 19. The OS14 is an example of system software, while the noise reduction device 1, the 3D audio device 15, the HFT16, the image quality setting device 17, and the background service 18 (hereinafter collectively referred to as applications 1, 15-18) are examples of application software.

[0014] <os14> OS14 has the function of managing the operating status of applications 1, 15-18. OS14 receives signals Se (hereinafter referred to as "operating status signals Se") related to the operating status of applications 1, 15-18 as input. Based on the operating status signals Se, OS14 estimates the usage rate X of processor 12. For example, OS14 estimates the usage rate X of processor 12 by adding the processing load of the running applications 1, 15-18 and the current processing load of OS14. OS14 outputs the estimated usage rate X of processor 12 to the noise reduction device 1.

[0015] <Noise Reduction Device 1> Referring to Figure 1, the noise reduction device 1 is an Active Noise Control Device (ANC) for reducing noise d generated inside the passenger compartment 8 of the vehicle 3. More specifically, the noise reduction device 1 generates a canceling sound y that is out of phase with the noise d, and reduces the noise d by causing the generated canceling sound y to interfere with the noise d.

[0016] The noise reduction device 1 includes a plurality of acceleration sensors 21 that generate a reference signal r corresponding to noise d, a plurality of speakers 22 (an example of a sound cancellation output device) that output a cancellation sound y to cancel out noise d, a plurality of error microphones 23 that generate an error signal e based on noise d and sound cancellation y, and a control device 25 that controls the plurality of speakers 22 based on the reference signal r and the error signal e.

[0017] <Accelerometer 21> Referring to Figure 1, each acceleration sensor 21 is installed on the corresponding suspension 6. The acceleration sensor 21 detects the acceleration of the suspension 6 in response to the noise d and generates a reference signal r corresponding to the acceleration of the suspension 6.

[0018] <Speaker 22> Referring to Figure 1, each speaker 22 is installed in a location in the vehicle 3 other than the passenger seat 9 (for example, the side door of the passenger seat 9 or the space behind the passenger seat 9). In other embodiments, the speaker 22 may be installed on the passenger seat 9 (for example, the headrest 9C of the passenger seat 9).

[0019] <Error Microphone 23> Referring to Figure 1, each error microphone 23 is installed on the headrest 9C of the passenger seat 9. In other embodiments, the error microphones 23 may be installed in locations other than the passenger seats 9 in the vehicle 3 (for example, on the ceiling above the passenger seats 9).

[0020] <Control device 25> Referring to Figure 3, the control device 25 has, as functional components, a plurality of control signal generation units An (n=1 to N), a plurality of sound field learning units Bn (n=1 to N), and a processing control unit 27. In Figure 3, only the first control signal generation unit A1 and the Nth control signal generation unit AN are shown (the same applies to the plurality of sound field learning units Bn). Hereinafter, the plurality of control signal generation units An and the plurality of sound field learning units Bn will be collectively referred to as "a plurality of adaptive control units An and Bn". The plurality of adaptive control units An and Bn correspond to a plurality of speakers 22, respectively.

[0021] <Control signal generation unit An> Each control signal generation unit An of the control device 25 includes a control filter unit 34, a reference signal correction unit 35, and a control update unit 36.

[0022] The control filter unit 34 is composed of a control filter Wn (n=1 to N). The control filter Wn is composed of an FIR filter (finite impulse response filter). In other embodiments, the control filter Wn may be composed of a SAN filter (single frequency adaptive notch filter) or the like. The control filter unit 34 generates a control signal un (n=1 to N) for controlling the speaker 22 by filtering the reference signal r with the control filter Wn. The control filter unit 34 outputs the generated control signal un to the speaker 22 and the sound field learning unit Bn. When the control signal un is input to the speaker 22, the speaker 22 generates a cancellation sound y corresponding to the magnitude of the control signal un.

[0023] The reference signal correction unit 35 is composed of a second-order path filter C^n (n=1 to N). The second-order path filter C^n is a filter that shows an estimated value of the transfer function C of the second-order path from the speaker 22 to the error microphone 23. The second-order path filter C^n is composed of an FIR filter. In other embodiments, the second-order path filter C^n may be composed of a SAN filter or the like. The reference signal correction unit 35 corrects the reference signal r by applying filtering to the reference signal r using the second-order path filter C^n. The reference signal correction unit 35 outputs the corrected reference signal r to the control update unit 36.

[0024] The control update unit 36 ​​adaptively updates the control filter Wn using an adaptive algorithm such as the LMS algorithm (Least Mean Square Algorithm). More specifically, the control update unit 36 ​​adaptively updates the control filter Wn according to equation (1) below so that the error signal e output from the error microphone 23 is minimized.

number

[0025] <Sound Field Learning Department Bn> Each sound field learning unit Bn of the control device 25 includes a cancellation sound estimation signal generation unit 41, a secondary path update unit 42, a noise estimation signal generation unit 43, a primary path update unit 44, a cancellation sound estimation signal inversion unit 45, a noise estimation signal inversion unit 46, and a virtual error signal generation unit 47.

[0026] The negation sound estimation signal generation unit 41, like the reference signal correction unit 35, is composed of a second-order path filter C^n. The negation sound estimation signal generation unit 41 applies filtering to the control signal un using the second-order path filter C^n to generate a negation sound estimation signal y^n (n=1~N) that indicates the estimated value of the negation sound y. The negation sound estimation signal generation unit 41 outputs the generated negation sound estimation signal y^n to the negation sound estimation signal inversion unit 45.

[0027] The secondary path update unit 42 adaptively updates the secondary path filter C^n of the cancellation sound estimation signal generation unit 41 using an adaptive algorithm such as the LMS algorithm. More specifically, the secondary path update unit 42 updates the virtual error signal en output from the virtual error signal generation unit 47. v The quadratic path filter C^n is adaptively updated by equation (2) below so that (details below) is minimized.

number

[0028] Furthermore, when the secondary path update unit 42 updates the secondary path filter C^n of the sound cancellation estimation signal generation unit 41 as described above, the updated secondary path filter C^n is output to the reference signal correction unit 35, and the secondary path filter C^n of the reference signal correction unit 35 is updated.

[0029] The noise estimation signal generation unit 43 is composed of a first-order path filter H^n (n=1 to N). The first-order path filter H^n is a filter that shows an estimated value of the transfer function H of the first-order path from the noise source to the error microphone 23. The first-order path filter H^n is composed of, for example, an FIR filter. In other embodiments, the first-order path filter H^n may be composed of a SAN filter or the like. The noise estimation signal generation unit 43 generates a noise estimation signal d^n (n=1 to N) that shows an estimated value of noise d by filtering the reference signal r with the first-order path filter H^n. The noise estimation signal generation unit 43 outputs the generated noise estimation signal d^n to the noise estimation signal inversion unit 46.

[0030] The primary path update unit 44 adaptively updates the primary path filter H^n using an adaptive algorithm such as the LMS algorithm. More specifically, the primary path update unit 44 updates the virtual error signal en output from the virtual error signal generation unit 47. v The first-order path filter H^n is adaptively updated by equation (3) below so that (details below) is minimized.

number

[0031] The sound cancellation estimation signal inversion unit 45 inverts the polarity of the sound cancellation estimation signal y^n output from the sound cancellation estimation signal generation unit 41. The sound cancellation estimation signal inversion unit 45 outputs the sound cancellation estimation signal y^n with inverted polarity to the virtual error signal generation unit 47.

[0032] The noise estimation signal inversion unit 46 inverts the polarity of the noise estimation signal d^n output from the noise estimation signal generation unit 43. The noise estimation signal inversion unit 46 outputs the noise estimation signal d^n with the inverted polarity to the virtual error signal generation unit 47.

[0033] The virtual error signal generation unit 47 adds the error signal e output from the error microphone 23, the cancellation estimation signal y^n that has passed through the cancellation estimation signal inversion unit 45, and the noise estimation signal d^n that has passed through the noise estimation signal inversion unit 46 to generate a virtual error signal e v The virtual error signal generation unit 47 generates (n=1~N). v This is output to the secondary route update unit 42 and the primary route update unit 44.

[0034] <Processing Control Unit 27> The processing control unit 27 of the control device 25 controls the adaptive update processing and filtering processing in the multiple adaptive control units An and Bn by sending flags to the control update unit 36, secondary path update unit 42, and primary path update unit 44 of the multiple adaptive control units An and Bn to switch the processing of the control filter Wn, secondary path filter C^n, and primary path filter H^n. The adaptive update processing is the process of adaptively updating the control filter Wn, secondary path filter C^n, and primary path filter H^n (hereinafter referred to as "adaptive update filters Wn, C^n, and H^n"). The filtering processing is the process of filtering input signals (for example, a reference signal r or a control signal un) using the adaptive update filters Wn, C^n, and H^n.

[0035] More specifically, the processing control unit 27 controls the adaptive update processing and filtering processing in multiple adaptive control units An and Bn according to the processor usage rate X obtained from the OS 14. Hereinafter, the control of the adaptive update processing and filtering processing according to the processor usage rate X will be referred to as "processing control".

[0036] Referring to Figure 4, the processing control unit 27 stores a pattern table Tp. The pattern table Tp is a table that defines the relationship between multiple processing patterns i (i=1 to I) and their processing amounts in multiple adaptive control units An and Bn. For example, the pattern table Tp defines the processing pattern i number (1 to I), the processing amount of processing pattern i, and the content of processing pattern i.

[0037] In the pattern table Tp, the processing amount of processing pattern i is defined as a percentage (relative value). For example, if the processing amount of a certain processing pattern i is 25%, then 25% of the processing amount is required to execute that processing pattern i. In other embodiments, the processing amount of processing pattern i may be defined as MIPS (absolute value).

[0038] In the pattern table Tp, the content of processing pattern i is defined by a sequence of processing flags (0, 1, or 2) for adaptive update filters Wn, C^n, and H^n. The processing flags, from the beginning (left end) to the end (right end), correspond to control filter W1, secondary path filter C^1, primary path filter H^1, ..., control filter WN, secondary path filter C^N, and primary path filter H^N. When the processing flag is 2, the processing control unit 27 executes adaptive update processing and filtering processing. When the processing flag is 1, the processing control unit 27 does not execute adaptive update processing and executes filtering processing. In other words, when the processing flag is 1, the processing control unit 27 executes filtering processing using adaptive update filters Wn, C^n, and H^n as fixed filters. When the processing flag is 0, the processing control unit 27 stops adaptive update processing and filtering processing.

[0039] In pattern table Tp, in processing pattern 1, the processing flag for all adaptive update filters Wn, C^n, and H^n is set to 2. Therefore, all adaptive update filters Wn, C^n, and H^n are adaptively updated. In processing patterns 2 and 3, the processing flags for adaptive update filters Wn, C^n, and H^n are divided into 2, 1, and 0. Therefore, only some of the adaptive update filters Wn, C^n, and H^n are adaptively updated. In processing pattern I, the processing flag for all adaptive update filters Wn, C^n, and H^n is set to 1 or 0. Therefore, the adaptive update of all adaptive update filters Wn, C^n, and H^n is stopped.

[0040] <Processing Control> Referring to Figure 5, when processing control is started, the processing control unit 27 obtains the processor usage rate X of the processor 12 from the OS 14 (step ST1).

[0041] Next, the processing control unit 27 calculates the free rate Xa of the processor 12 based on the utilization rate X of the processor 12 (step ST2). For example, the processing control unit 27 calculates the free rate Xa of the processor 12 using the following equation (4). Xa = Xu - X ... (4) In equation (4) above, Xu represents the upper limit of the processor 12's utilization X (hereinafter referred to as "upper limit Xu"). The upper limit Xu of utilization X is a parameter that is set in advance. The upper limit Xu of utilization X should be set with a margin over the processing limit of the processor 12. The upper limit Xu of utilization X should be defined in percentages or MIPS, similar to the processing amount of processing pattern i.

[0042] Next, the processing control unit 27 calculates the usable processing amount Xb of the noise reduction device 1 based on the free rate Xa of the processor 12 (step ST3). For example, the processing control unit 27 calculates the usable processing amount Xb of the noise reduction device 1 using the following equation (5). Xb = Xc + Xa ... (5) In equation (5) above, Xc represents the current processing capacity of the noise reduction device 1 (hereinafter referred to as "current processing capacity Xc"). The current processing capacity Xc of the noise reduction device 1 is read from the pattern table Tp based on the current processing pattern i. In equation (5) above, if Xa < 0, it means that the current processing capacity Xc of the noise reduction device 1 exceeds the usable processing capacity Xb of the noise reduction device 1. In this case, it is necessary to reduce the processing capacity of processing pattern i.

[0043] Next, the processing control unit 27 selects one of the multiple processing patterns i in the pattern table Tp based on the available processing capacity Xb of the noise reduction device 1 (step ST4). More specifically, the processing control unit 27 selects one of the multiple processing patterns i such that the processing amount of processing pattern i does not exceed the available processing capacity Xb of the noise reduction device 1. For example, if the available processing capacity Xb of the noise reduction device 1 is 30%, and the processing control unit 27 selects processing pattern 1 (processing amount 50%) from the pattern table Tp, the processing amount of processing pattern i will exceed the available processing capacity Xb of the noise reduction device 1. In such a case, the processing control unit 27 should select processing patterns 2 or 3 (processing amount 25%).

[0044] Next, the processing control unit 27 executes adaptive update processing and filtering processing in the multiple adaptive control units An and Bn according to the processing pattern i selected in step ST4 (step ST5). If processing pattern i could not be selected in step ST4, the processing control unit 27 may stop the functions of the noise reduction device 1 (that is, the processing control unit 27 may stop all processing of the noise reduction device 1).

[0045] <Effects> The noise reduction device 1 is designed to have a higher control effect in the vicinity of the error microphone 23. Therefore, in this embodiment, the error microphone 23 is installed on the headrest 9C of the occupant seat 9. This allows the occupant's head to be brought closer to the error microphone 23, thereby increasing the control effect that the occupant can perceive.

[0046] On the other hand, if the error microphone 23 is installed on the headrest 9C of the passenger seat 9, the position of the error microphone 23 changes significantly when the fore-aft position of the passenger seat 9 is adjusted or when the seat back 9B of the passenger seat 9 is reclined, causing a large change in the transfer function C of the secondary path from the speaker 22 to the error microphone 23. Consequently, if the difference between the transfer function C of the secondary path and the secondary path filter C^n becomes large, there is a risk that the noise reduction device 1 may not be able to sufficiently reduce noise d, or that noise d may be amplified. Therefore, the control device 25 adaptively updates the secondary path filter C^n. This allows the secondary path filter C^n to change in response to changes in the transfer function C of the secondary path. As a result, the noise reduction device 1 can sufficiently reduce noise d and suppress the amplification of noise d.

[0047] On the other hand, if all adaptive update filters Wn, C^n, and H^n were to be updated every time noise d is controlled, the computational load on processor 12 would increase, requiring a high-performance and expensive processor 12. Therefore, the control device 25 reduces the update frequency of adaptive update filters Wn, C^n, and H^n according to the pattern table Tp. This reduces the computational load on processor 12, making it possible to use an inexpensive processor 12.

[0048] Incidentally, the usage rate X of the processor 12 changes depending on the operating status of applications 1, 15-18, and the processing resources available to the noise reduction device 1 (i.e., the processing amount of the processor 12) also change. Therefore, even if the update frequency of the adaptive update filters Wn, C^n, and H^n is reduced as described above, there is a risk that sufficient processing resources for the adaptive update process may not be secured depending on the operating status of applications 1, 15-18. On the other hand, if the update frequency of the adaptive update filters Wn, C^n, and H^n is drastically reduced by considering only the securing of processing resources, the tracking performance to changes in noise d and transfer functions C and H will be significantly reduced, and there is a risk that noise d may not be sufficiently reduced or that noise d may be amplified. Therefore, the control device 25 controls the adaptive update process in multiple adaptive control units An and Bn according to the usage rate X of the processor 12. More specifically, the control device 25 determines whether or not to execute the adaptive update process according to the usage rate X of the processor 12. This makes it possible to fully utilize the processing resources according to the usage rate X of the processor 12 and achieve maximum noise reduction performance.

[0049] <<Second Embodiment>> Next, with reference to Figures 6 to 8, the active noise reduction device 51 according to the second embodiment (hereinafter abbreviated as "noise reduction device 51") will be described. Note that explanations of the same aspects as those of the first embodiment will be omitted as appropriate.

[0050] <Control device 53> Referring to Figure 6, the control device 53 of the noise reduction device 51 includes a plurality of control signal generation units An (n=1 to N), a plurality of sound field learning units Bn (n=1 to N), and a processing control unit 27, in addition to a utilization rate estimation unit 54.

[0051] <Usage rate estimation unit 54> The utilization rate estimation unit 54 of the control device 53 receives an output signal So from a functional unit Fm other than the noise reduction device 1 (hereinafter referred to as "other functional unit Fm"). The output signal So is an example of a signal relating to the operating status of the other functional unit Fm. The utilization rate estimation unit 54 estimates the utilization rate X of the processor 12 based on the output signal So from the other functional unit Fm and the current processing load of the noise reduction device 51. Hereinafter, the control for estimating the utilization rate X of the processor 12 will be referred to as "utilization rate estimation control".

[0052] Referring to Figure 7, the utilization rate estimation unit 54 stores a processing volume table Tx. The processing volume table Tx is a table that defines the relationship between other functional units Fm and their processing volumes. For example, the processing volume table Tx defines the number of the other functional unit Fm, the name of the other functional unit Fm, and the processing volume of the other functional unit Fm.

[0053] <Usage Rate Estimation Control> Referring to Figure 8, when utilization rate estimation control is started, the utilization rate estimation unit 54 receives an output signal So from another functional unit Fm (step ST11).

[0054] Next, the utilization rate estimation unit 54 calculates the other function processing amount Xo based on the output signals So from other function units Fm and the processing amount table Tx (step ST12). The other function processing amount Xo is the sum of the processing amounts of other function units Fm whose absolute value of output signal So is greater than 0 (i.e., other function units Fm that are currently operating). The utilization rate estimation unit 54 can calculate the other function processing amount Xo by determining whether the absolute value of the output signal So is greater than 0 for each of the other function units Fm, reading the processing amounts of the other function units Fm whose absolute value of output signal So is greater than 0 from the processing amount table Tx, and adding them up.

[0055] Next, the utilization rate estimation unit 54 estimates the utilization rate X of the processor 12 based on the processing amount X of other functions and the current processing amount of the noise reduction device 51 (step ST13). For example, the utilization rate estimation unit 54 estimates the utilization rate X of the processor 12 by adding the processing amount X of other functions and the current processing amount of the noise reduction device 51.

[0056] Next, the utilization rate estimation unit 54 outputs the estimated utilization rate X of the processor 12 to the processing control unit 27 (step ST14). The processing control unit 27 controls the adaptive update processing and filtering processing in the plurality of adaptive control units An and Bn in the same manner as in the first embodiment, according to the utilization rate X of the processor 12 output from the utilization rate estimation unit 54.

[0057] <Effects> In the second embodiment, the control device 53 can estimate the utilization rate X of the processor 12. Therefore, even if the OS 14 does not have a function to estimate the utilization rate X of the processor 12, it is possible to control the adaptive update processing and filtering processing in the multiple adaptive control units An and Bn according to the utilization rate X of the processor 12. This makes it possible to fully utilize processing resources according to the utilization rate X of the processor 12 and achieve maximum noise reduction performance.

[0058] <Variation> In the second embodiment, output signals So from multiple functional units Fm are used as signals relating to the operating status of the multiple functional units Fm. In other embodiments, signals that directly indicate the operating status of the multiple functional units Fm (hereinafter referred to as "status indicator signals") may be used as signals relating to the operating status of the multiple functional units Fm. For example, the status indicator signals include 0 (stopped) or 1 (operating) as an operating status flag. The utilization rate estimation unit 54 estimates the utilization rate X of the processor 12 by adding the processing amount of other functional units Fm that are outputting a status indicator signal that includes 1 as an operating status flag (i.e., other functional units Fm that are operating) and the current processing amount of the noise reduction device 51.

[0059] <<Third Embodiment>> Next, the vehicle 61 according to the third embodiment will be described with reference to Figures 9 and 10. Note that explanations of the same aspects as those in the first embodiment will be omitted as appropriate.

[0060] <ecu63> Referring to Figure 9, the ECU 63 of the vehicle 61 is equipped with middleware 64 as a functional unit Fm, in addition to OS 14 and applications 1, 15-18. OS 14, noise reduction device 1, and middleware 64 constitute an active noise reduction system 65.

[0061] <Middleware 64> Middleware 64 is positioned between OS 14 and applications 1, 15-18, and assists the functions of both. Functionally, middleware 64 includes an operational status input / output unit 67 and a usage rate estimation unit 68.

[0062] <Operating status input / output unit 67> The operating status input / output unit 67 of the middleware 64 receives a first operating status signal Se1 from applications 1, 15-18. The first operating status signal Se1 is a signal relating to the current operating status of applications 1, 15-18. The operating status input / output unit 67 outputs the first operating status signal Se1 received from applications 1, 15-18 to the usage rate estimation unit 68.

[0063] The operating state input / output unit 67 outputs a second operating state signal Se2 to applications 1, 15-18. The second operating state signal Se2 is a signal relating to the current operating state of the other applications 1, 15-18 (i.e., applications other than the application to which the second operating state signal Se2 is input). Applications 1, 15-18 may estimate the operating state of the other applications 1, 15-18 based on the second operating state signal Se2, and determine their own operating state based on the estimated operating state of the other applications 1, 15-18.

[0064] <Usage rate estimation section 68> Referring to Figure 10, the middleware 64's usage estimation unit 68 stores a processing amount table Tx. The processing amount table Tx is a table that defines the relationship between multiple functional units Fm and their processing amounts. For example, the processing amount table Tx defines the numbers of multiple functional units Fm, the names of multiple functional units Fm, the operating states of multiple functional units Fm, and the processing amounts of multiple functional units Fm. For some functional units Fm (for example, the noise reduction device 1 and the 3D audio device 15), the processing amount table Tx defines multiple operating states and corresponding multiple processing amounts.

[0065] The utilization estimation unit 68 estimates the utilization rate X of the processor 12 based on the first operating state signal Se1 input from applications 1, 15-18 via the operating state input / output unit 67 and the processing amount table Tx. For example, suppose a first operating state signal Se1 indicating operating state 2 is input from the 3D audio device 15 and a first operating state signal Se1 indicating operating state 1 is input from the HFT 16. In this case, the utilization estimation unit 68 estimates the utilization rate X of the processor 12 to be 25% by adding the processing amount of the 3D audio device 15 (operating state 2) at 10%, the processing amount of the HFT 16 (operating state 1) at 10%, and the processing amount of the OS 14 (a function unit Fm that is always running) at 5%.

[0066] The utilization rate estimation unit 68 outputs the estimated utilization rate X to applications 1, 15-18. The control device 25 of the noise reduction device 1 controls the adaptive update process and filtering process in the plurality of adaptive control units An and Bn in the same manner as in the first embodiment, according to the utilization rate X of the processor 12 output from the utilization rate estimation unit 68.

[0067] <Effects> In the third embodiment, middleware 64 can estimate the utilization rate X of processor 12. Therefore, even if OS 14 does not have a function to estimate the utilization rate X of processor 12, it is possible to control the adaptive update processing and filtering processing in the multiple adaptive control units An and Bn according to the utilization rate X of processor 12. This makes it possible to fully utilize processing resources according to the utilization rate X of processor 12 and achieve maximum noise reduction performance.

[0068] In the second embodiment, since the utilization rate estimation unit 54 is included in the noise reduction device 51, adopting a detailed processing amount table Tx may increase the processing load of the noise reduction device 51. Therefore, a simple processing amount table Tx is adopted in which only one processing amount is defined for each functional unit Fm (Figure 7). In contrast, in the third embodiment, since the utilization rate estimation unit 68 is included in the middleware 64, adopting a detailed processing amount table Tx does not increase the processing load of the noise reduction device 1. Therefore, a detailed processing amount table Tx is adopted in which multiple operating states and multiple processing amounts are defined for some functional units Fm (Figure 10). As a result, the utilization rate X of the processor 12 can be estimated accurately without increasing the processing load of the noise reduction device 1.

[0069] <<Fourth Embodiment>> Next, with reference to Figures 11 to 14, the noise reduction device 71 (particularly the control device 72) and the operating system 73 (hereinafter abbreviated as "OS73") according to the fourth embodiment will be described. The noise reduction device 71 and OS73 constitute the active noise reduction system 74. OS73 is an example of system software. Details similar to those in the first embodiment will be omitted as appropriate.

[0070] <Control device 72> Referring to Figure 11, the control device 72 has a processing control unit 75. The processing control unit 75 obtains the processor usage rate X of the processor 12 from the OS 73. The processing control unit 75 controls the adaptive update processing and filtering processing in a plurality of adaptive control units An and Bn according to the processor usage rate X of the processor 12 obtained from the OS 73. Hereinafter, the control of the adaptive update processing and filtering processing according to the processor usage rate X of the processor 12 will be referred to as "processing control".

[0071] Referring to Figure 12, the processing control unit 75 stores a pattern reading table Tr. The pattern reading table Tr is a table that defines the relationship between the number of the error microphone 23 whose position has changed and the numbers of the multiple processing patterns i. The numbers of the multiple processing patterns i are arranged so that the priority of the processing patterns i decreases from the beginning (left end) to the end (right end).

[0072] Generally, the greater the processing load of processing pattern i, the wider the range that the noise reduction device 71 can control, or the more control functions it can perform. Therefore, in this embodiment, the priority of processing pattern i corresponds to the magnitude of the processing load of processing pattern i. However, in other embodiments, the priority of processing pattern i may be determined based on factors other than the magnitude of the processing load of processing pattern i.

[0073] <Processing Control> Referring to Figure 13, when processing control is started, the processing control unit 75 obtains the processor usage rate X of the processor 12 from the OS 73 (step ST21).

[0074] Next, the processing control unit 75 detects changes in the positions of the multiple error microphones 23 (step ST22). For example, the processing control unit 75 detects changes in the positions of the multiple error microphones 23 based on changes in the positions of the multiple occupant seats 9. More specifically, the processing control unit 75 detects changes in the positions of the error microphones 23 if at least one of the following conditions 1 to 3 is met, or if all of the following conditions 4 to 6 are met. On the other hand, if all of the following conditions 1 to 3 are not met, and at least one of the following conditions 4 to 6 is not met, the processing control unit 75 does not detect changes in the positions of the error microphones 23. Note that the second front-to-back threshold, second height threshold, and second angle threshold in the following conditions 4 to 6 are set to smaller values ​​than the first front-to-back threshold, first height threshold, and first angle threshold in the following conditions 1 to 3, respectively. Condition 1: The amount of change in the fore-aft position of the occupant seat 9 is greater than the first fore-aft threshold. Condition 2: The change in the height of the occupant seat 9 is greater than the first height threshold. Condition 3: The change in the tilt angle of the occupant seat 9 is greater than the first angle threshold. Condition 4: The amount of change in the fore-aft position of the occupant seat 9 is greater than the second fore-aft threshold. Condition 5: The change in the height of the occupant seat 9 is greater than the second height threshold. Condition 6: The change in the tilt angle of the occupant seat 9 is greater than the second angle threshold.

[0075] Next, the processing control unit 75 reads out a plurality of processing patterns i corresponding to the error microphone 23 whose position has changed, based on the pattern reading table Tr (step ST23).

[0076] Next, the processing control unit 75 calculates the free rate Xa of the processor 12 based on the utilization rate X of the processor 12 (step ST24). The method for calculating the free rate Xa of the processor 12 is the same as in the first embodiment, so the explanation is omitted.

[0077] Next, the processing control unit 75 calculates the usable processing amount Xb of the noise reduction device 71 based on the free rate Xa of the processor 12 (step ST25). The method for calculating the usable processing amount Xb of the noise reduction device 71 is the same as in the first embodiment, so the explanation is omitted.

[0078] Next, the processing control unit 75 determines whether the processing resources are sufficient based on the multiple processing patterns i read in step ST23, the available processing amount Xb of the noise reduction device 71, and the pattern table Tp (see Figure 4) (step ST26). More specifically, the processing control unit 75 determines that the processing resources are sufficient if the processing amount of at least one of the multiple processing patterns i read in step ST23 is less than or equal to the available processing amount Xb of the noise reduction device 71. On the other hand, the processing control unit 75 determines that the processing resources are insufficient if the processing amounts of all processing patterns i read in step ST23 exceed the available processing amount Xb of the noise reduction device 71.

[0079] If there are sufficient processing resources (step ST26: Yes), the processing control unit 75 selects one of the multiple processing patterns i read in step ST23 (for example, the processing pattern i with the largest processing load) (step ST27).

[0080] Next, the processing control unit 75 executes adaptive update processing and filtering processing in the multiple adaptive control units An and Bn according to the selected processing pattern i (step ST28).

[0081] If processing resources are insufficient (step ST26: No), the processing control unit 75 stops the adaptive update processing and filtering processing in the adaptive control units An and Bn that correspond to the error microphone 23 whose position has changed (step ST29).

[0082] Next, the processing control unit 75 outputs a processing amount signal Sx to the OS 73 (step ST30). The processing amount signal Sx is a signal relating to the processing amount of processing pattern i read in step ST23 (i.e., the processing amount of processing pattern i that could not be executed due to insufficient processing resources).

[0083] <os73> Referring to Figure 14, OS73 stores the priority table Tpr. The priority table Tpr defines the relationship between applications 71, 15-18 and their priorities. The priorities of applications 71, 15-18 are determined based on the importance of the processing performed by applications 71, 15-18.

[0084] When OS73 receives a processing amount signal Sx from the processing control unit 75 of the control device 72, it reduces the processing amount (e.g., processing frequency) of at least one of the applications 15-18 other than the noise reduction device 71 based on the processing amount signal Sx and the priority table Tpr. More specifically, OS73 reduces the processing amount of applications 15-18 other than the noise reduction device 71 that have a lower priority than the noise reduction device 71 (in the example in Figure 14, the image quality setting device 17 or background service 18). This reduces the utilization rate X of the processor 12.

[0085] OS73 transmits the reduced processor 12 utilization rate X to the processing control unit 75 of the control device 72. Based on the processor 12 utilization rate X obtained from OS73, the processing control unit 75 executes new processing control. In this new processing control, because the processor 12 utilization rate X has decreased, the determination in step ST26 becomes Yes, and adaptive update processing and filtering processing are executed in multiple adaptive control units An and Bn.

[0086] <Effects> OS73 reduces the processing load of applications 15-18 other than the noise reduction device 71 based on the processing load signal Sx and the priority table Tpr. This increases the processing resources available to the noise reduction device 71. As a result, it can increase the number of situations in which adaptive update processing can be performed, improving its ability to track changes in noise d and changes in transfer functions C and H.

[0087] <Variation> In the fourth embodiment, the processing control unit 75 detects changes in the positions of multiple error microphones 23 based on changes in the positions of multiple occupant seats 9. In other embodiments, the processing control unit 75 may detect changes in the position of the first error microphone 23 based on an error signal e output from one error microphone 23 (hereinafter referred to as the "first error microphone 23") and an error signal e output from another error microphone 23 (hereinafter referred to as the "second error microphone 23"). For example, the processing control unit 75 detects changes in the position of the error microphone 23 when the signal level of the error signal e output from the first error microphone 23 (hereinafter referred to as the "first signal level") and the signal level of the error signal e output from the second error microphone 23 (hereinafter referred to as the "second signal level") satisfy all of the following conditions A to C. On the other hand, the processing control unit 75 does not detect changes in the position of the error microphone 23 when the first signal level and the second signal level do not satisfy at least one of the following conditions A to C. Condition A: The absolute value of the difference between the first signal level and the second signal level is greater than or equal to the first reference value. Condition B: The time variation of the first signal level is greater than or equal to the second reference value. Condition C: The first signal level is equal to or greater than the third reference value.

[0088] In the first to fourth embodiments described above, the control devices 25, 53, and 72 have multiple control signal generation units An and multiple sound field learning units Bn. As shown in Figure 15, in other embodiments, the control devices 25, 53, and 72 may each have only one control signal generation unit An and one sound field learning unit Bn.

[0089] In the first to fourth embodiments described above, the control devices 25, 53, and 72 include multiple adaptive update filters Wn, C^n, and H^n. In other embodiments, the control devices 25, 53, and 72 may include only one adaptive update filter.

[0090] In the first to fourth embodiments described above, the noise reduction devices 1, 51, and 71 are applied to the passenger compartment 8 of the vehicle 3. In other embodiments, the noise reduction devices 1, 51, and 71 may be applied to the interior space of a moving object other than the vehicle 3 (for example, a ship or an aircraft), or to the interior space of a fixed object (for example, a house).

[0091] This concludes the description of specific embodiments, but the present invention is not limited to the above embodiments or modifications and can be broadly modified and implemented.

[0092] <Summary of Embodiments> The active noise reduction devices 1, 51, 71 mounted on the control unit 11 equipped with the processor 12 include a noise cancellation output device 22 that outputs a cancellation sound y to cancel out noise d, an error microphone 23 that generates an error signal e based on the noise d and the cancellation sound y, and control devices 25, 53, 72 that control the noise cancellation output device 22 based on the error signal e, wherein the control devices 25, 53, 72 include at least one adaptively updatable filter Wn, C^n, H^n and control the adaptive update process of the filter Wn, C^n, H^n according to the utilization rate X of the processor 12.

[0093] According to this embodiment, by controlling the adaptive update process of filters Wn, C^n, and H^n according to the usage rate X of processor 12, processing resources (processing amount of processor 12) can be utilized efficiently. As a result, maximum noise reduction performance can be achieved.

[0094] The at least one filter Wn, C^n, H^n includes a control filter Wn that generates a control signal un for controlling the sound cancellation output device 22, and the control devices 25, 53, 72 control the adaptive update process of the control filter Wn according to the utilization X of the processor 12.

[0095] According to this embodiment, by controlling the adaptive update process of the control filter Wn according to the usage rate X of the processor 12, processing resources can be utilized more efficiently. As a result, maximum noise reduction performance can be achieved.

[0096] The at least one filter Wn, C^n, H^n further includes a second-order path filter C^n that shows an estimate of the transfer function C from the sound cancellation output device 22 to the error microphone 23, and the control devices 25, 53, 72 control the adaptive update process of the control filter Wn and the second-order path filter C^n according to the utilization X of the processor 12.

[0097] According to this embodiment, by controlling the adaptive update process of the control filter Wn and the secondary path filter C^n according to the usage rate X of the processor 12, processing resources can be utilized more efficiently. As a result, maximum noise reduction performance can be achieved.

[0098] The at least one filter Wn, C^n, H^n further includes a first-order path filter H^n that shows an estimate of the transfer function H from the noise source to the error microphone 23, and the control devices 25, 53, 72 control the adaptive update process of the control filter Wn, the second-order path filter C^n, and the first-order path filter H^n according to the utilization X of the processor 12.

[0099] According to this embodiment, by controlling the adaptive update process of the control filter Wn, the secondary path filter C^n, and the primary path filter H^n according to the usage rate X of the processor 12, processing resources can be utilized more efficiently. As a result, maximum noise reduction performance can be achieved.

[0100] The active noise reduction device 51 is mounted on the control unit 11 as one of a plurality of functional units Fm, the control device 53 stores a processing amount table Tx that defines the relationship between the plurality of functional units Fm and their processing amounts, receives a signal So related to the operating state of the plurality of functional units Fm, estimates the processing amount of the plurality of functional units Fm based on the processing amount table Tx and the signal So related to the operating state of the plurality of functional units Fm, and estimates the utilization rate X of the processor 12 based on the processing amount of the plurality of functional units Fm.

[0101] According to this embodiment, even if the operating system 14 installed in the control unit 11 does not have a function to estimate the usage rate X of the processor 12, the control device 53 can estimate the usage rate X of the processor 12.

[0102] The control devices 25, 53, and 72 store a pattern table Tp that defines the relationship between a plurality of processing patterns i and their processing amounts, and based on the utilization rate X of the processor 12, they select one of the plurality of processing patterns i in the pattern table Tp and execute the adaptive update processing of the filters Wn, C^n, and H^n according to the selected processing pattern i.

[0103] According to this embodiment, adaptive update processing of filters Wn, C^n, and H^n can be performed according to the optimal processing pattern i selected from the pattern table Tp. Therefore, processing resources can be utilized more efficiently.

[0104] Multiple sound censorship output devices 22 are provided, and the control devices 25, 53, and 72 correspond to the multiple sound censorship output devices 22 and have multiple adaptive control units An and Bn capable of executing the adaptive update processing of the filters Wn, C^n, and H^n. They store a pattern table Tp that defines the relationship between multiple processing patterns i in the multiple adaptive control units An and Bn and the amount of processing. Based on the usage rate X of the processor 12, they select one of the multiple processing patterns i in the pattern table Tp and execute the adaptive update processing of the filters Wn, C^n, and H^n in the multiple adaptive control units An and Bn according to the selected processing pattern i.

[0105] According to this embodiment, multiple adaptive control units An and Bn can be comprehensively controlled using a pattern table Tp. Therefore, processing resources can be utilized more efficiently.

[0106] Multiple error microphones 23 are provided, and the control devices 25, 53, and 72 have multiple adaptive control units An and Bn capable of performing the adaptive update processing of the filters Wn, C^n, and H^n based on the error signals e from the multiple error microphones 23. They store a pattern table Tp that defines the relationship between multiple processing patterns i in the multiple adaptive control units An and Bn and the amount of processing. They detect changes in the position of the multiple error microphones 23, and based on the position of the error microphone 23 and the utilization rate X of the processor 12, they select one of the multiple processing patterns i in the pattern table Tp and perform the adaptive update processing of the filters Wn, C^n, and H^n in the multiple adaptive control units An and Bn according to the selected processing pattern i.

[0107] According to this embodiment, when the position of the error microphone 23 changes, adaptive update processing can be performed according to the optimal processing pattern i corresponding to the change in the position of the error microphone 23. Therefore, processing resources can be utilized more efficiently.

[0108] An active noise reduction system 74 comprises an active noise reduction device 71 mounted on the control unit 11 as one of several application software programs 71, 15-18, and system software 73 mounted on the control unit 11 together with the active noise reduction device 71, wherein the control device 72 performs the adaptive update processing of the filters Wn, C^n, and H^n according to processing pattern i, outputs a processing amount signal Sx related to the processing amount of processing pattern i to the system software 73, and the system software 73 reduces the processing amount of the application software programs 15-18 other than the active noise reduction device 71 based on the processing amount signal Sx.

[0109] According to this embodiment, by reducing the processing load of application software 15-18 other than the active noise reduction device 71, the processing resources available to the active noise reduction device 71 can be increased. This increases the number of situations in which adaptive update processing of filters Wn, C^n, and H^n can be performed, thereby improving the tracking performance to changes in noise d and changes in the sound field.

[0110] The system software 73 stores a priority table Tpr that defines the relationship between the multiple application software programs 71, 15-18 and their priorities, and based on the processing amount signal Sx and the priority table Tpr, it reduces the processing amount of the application software programs 15-18 that have a lower priority than the active noise reduction device 71.

[0111] According to this embodiment, it is possible to increase the processing resources available to the active noise reduction device 71 while maintaining the functions of the high-priority application software 15-18. [Explanation of Symbols]

[0112] <<First Embodiment>> 1: Active noise reduction device (an example of application software) 11: ECU (An example of a control unit) 12: Processor 14: OS (An example of system software) 15: 3D audio device (an example of application software) 16: HFT (An example of application software) 17: Image quality setting device (an example of application software) 18: Background services (an example of application software) 19: Active noise reduction system 22: Speaker (an example of a sound-canceling output device) 23: Error Microphone 25: Control device An: Control signal generation unit (an example of an adaptive control unit) Bn: Sound field learning unit (an example of an adaptive control unit) Wn: Control filter C^n: Quadratic path filter H^n: Primary path filter Fm: Functional section <<Second Embodiment>> 51: Active noise reduction device (an example of application software) 53: Control device <<Third Embodiment>> 63: ECU (An example of a control unit) 65: Active Noise Reduction System <<Fourth Embodiment>> 71: Active noise reduction device (an example of application software) 72: Control device 73: OS (An example of system software) 74: Active Noise Reduction System

Claims

1. An active noise reduction device mounted on a control unit equipped with a processor, A noise cancellation output device that outputs noise cancellation sound to cancel out noise, An error microphone that generates an error signal based on the aforementioned noise and the aforementioned cancellation sound, The system includes a control device that controls the sound-canceling output device based on the error signal, The control device is Includes at least one adaptively updatable filter, An active noise reduction device that controls the adaptive update process of the filter according to the usage rate of the processor.

2. The at least one filter includes a control filter that generates a control signal for controlling the sound-canceling output device, The active noise reduction device according to claim 1, wherein the control device controls the adaptive update process of the control filter according to the utilization rate of the processor.

3. The at least one filter further includes a quadratic path filter that shows an estimated value of the transfer function from the sound cancellation output device to the error microphone, The active noise reduction device according to claim 2, wherein the control device controls the adaptive update process of the control filter and the secondary path filter according to the utilization rate of the processor.

4. The at least one filter further includes a first-order path filter that shows an estimate of the transfer function from the noise source to the error microphone, The active noise reduction device according to claim 3, wherein the control device controls the adaptive update process of the control filter, the secondary path filter, and the primary path filter according to the utilization rate of the processor.

5. The aforementioned active noise reduction device is mounted on the control unit as one of several functional units. The control device is A processing volume table is stored that defines the relationship between the multiple functional units and their processing volumes. The system receives signals relating to the operating status of the multiple functional units. Based on the processing amount table and the signals relating to the operating status of the plurality of functional units, the processing amount of the plurality of functional units is estimated. An active noise reduction device according to any one of claims 1 to 4, wherein the utilization rate of the processor is estimated based on the processing amount of the plurality of functional units.

6. The control device is A pattern table is stored that defines the relationship between multiple processing patterns and their processing load. Based on the utilization rate of the processor, one of the multiple processing patterns in the pattern table is selected. An active noise reduction device according to any one of claims 1 to 4, which performs the adaptive update process of the filter according to the selected processing pattern.

7. Multiple sound-canceling output devices are provided, The control device is It has a plurality of adaptive control units that correspond to the plurality of sound cancellation output devices and are capable of performing the adaptive update process of the filter, A pattern table is stored which defines the relationship between multiple processing patterns in the multiple adaptive control units and the processing amount. Based on the utilization rate of the processor, one of the multiple processing patterns in the pattern table is selected. An active noise reduction device according to any one of claims 1 to 4, wherein the adaptive update process of the filter in the plurality of adaptive control units is performed according to the selected processing pattern.

8. Multiple error microphones are provided. The control device is The system includes a plurality of adaptive control units capable of performing the adaptive update process of the filter based on the error signals from the plurality of error microphones, A pattern table is stored which defines the relationship between multiple processing patterns in the multiple adaptive control units and the processing amount. The change in the position of the multiple error microphones is detected, Based on the position of the error microphone and the utilization rate of the processor, one of the plurality of processing patterns in the pattern table is selected. An active noise reduction device according to any one of claims 1 to 4, wherein the adaptive update process of the filter in the plurality of adaptive control units is performed according to the selected processing pattern.

9. An active noise reduction device according to any one of claims 1 to 4, which is mounted on the control unit as one of several application software programs, An active noise reduction system comprising: an active noise reduction device and system software mounted on the control unit; The control device is The adaptive update process of the filter is executed according to the processing pattern. A processing amount signal relating to the processing amount of the processing pattern is output to the system software. The system software is an active noise reduction system that reduces the processing load of application software other than the active noise reduction device based on the processing load signal.

10. The aforementioned system software is A priority table is stored that defines the relationship between the aforementioned multiple application software programs and their priorities. The active noise reduction system according to claim 9, which reduces the processing amount of application software with a lower priority than the active noise reduction device based on the processing amount signal and the priority table.

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