JP4185216B2 - Loudspeaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a loudspeaker device that forms an arbitrary directivity characteristic and acoustic characteristic for sound to be emitted by active control.
[0002]
[Prior art]
Conventionally, a horn speaker system has been used to control the directivity characteristics of loud sounds. Hereinafter, a conventional loudspeaker will be described with reference to FIGS.
[0003]
In FIG. 9, 23 is a horn driver, 24 is a horn that controls the direction and angle of sound radiation, 25 is a horn sound radiation surface, i is the aperture of the horn sound radiation surface 25, and arrow k is the progression of sound in the horn 24. Indicates direction.
[0004]
In general, the narrower the directivity angle, the larger the aperture i of the horn acoustic radiation surface 25. Further, since it is necessary to reduce the frequency change of the acoustic impedance of the horn 24 in order to reduce the disturbance of the sound pressure frequency characteristic of the radiated sound, the horn 24 has a cross-sectional area perpendicular to the traveling direction k of the sound wave, It is changing continuously and smoothly.
[0005]
In the loudspeaker having such a configuration, the sound wave reproduced by the horn driver 23 is guided in the direction of the arrow k inside the horn 24 and radiated to the outside from the horn acoustic radiation surface 25 in a state where the directivity is controlled. The
[0006]
In FIG. 10, reference numeral 23 denotes a horn driver, 26 denotes a horn having a folded structure, 25 denotes a horn acoustic radiation surface, and an arrow k denotes a sound traveling direction in the horn 26.
[0007]
The horn 26 in FIG. 10 has a folding structure of one or more times between the horn driver 23 and the horn acoustic radiation surface 25, and constitutes a long horn length without increasing the external dimension e of the device.
[0008]
[Problems to be solved by the invention]
However, in the conventional horn speaker system shown in FIG. 9, it is necessary to enlarge the horn acoustic radiation surface 25 in order to achieve narrow directivity. Further, since the directivity of the loud sound emitted by the shape of the horn 24 is uniquely determined, it is necessary to replace the horn 24 according to the required directivity.
[0009]
Further, in the horn speaker system using the horn 26 having the conventional folded structure shown in FIG. 10, since acoustic reflection occurs inside the horn 26, the frequency characteristic of the reproduced loud sound is greatly disturbed.
[0010]
Thus, in the prior art, a loudspeaker that easily realizes good arbitrary directivity and acoustic characteristics is not realized.
[0011]
The present invention solves the above problems, and its purpose is to realize a plurality of directional characteristics from narrow directional characteristics to wide directional characteristics by signal processing without changing the configuration of the apparatus, and to achieve excellent frequency characteristics. It is an object to provide a loudspeaker device capable of emitting loudspeaker sounds having
[0012]
[Means for Solving the Problems]
The loudspeaker according to the present invention includes a first sound source and a second sound source, a signal generating means for outputting an acoustic signal, a delay in which the acoustic signal is input, and a delay time is given to the input acoustic signal for output. A first detector that is installed in the vicinity of the first sound source, detects the sound radiated by the first sound source and the second sound source , converts the sound into an electrical signal, and outputs the electric signal; The output signal of the detector and the output signal of the delay device are input, an adder that adds and outputs the output signal of the first detector and the output signal of the delay device, the acoustic signal and the An output signal of the adder is input, and a first signal processing means for outputting a correction signal that makes the output signal of the adder small with respect to the acoustic signal, and installed in the vicinity of the second sound source. , electrical signals to detect the sound of the first sound and the second sound is emitted The second detector that converts and outputs the output signal and the output signal of the first signal processing means are input, and the output signal of the second detector with respect to the output signal of the first signal processing means And a second signal processing means for outputting to the second sound source a control signal such that the output signal of the first signal processing means is input to the first sound source. The sound source and the second sound source continuously change a horn driver that converts an acoustic signal of the acoustic signal source into air vibration, and a wave front of the air vibration output from the horn driver in a traveling direction of the sound wave. The horn driver of the first sound source and the second sound source is arranged so that acoustic radiation faces each other, and the number of times of folding of the horn is an odd number. The above purpose It is made.
[0016]
In one embodiment, the first signal processing means includes a first filter that inputs the acoustic signal, a first coefficient update that inputs an output signal of the first filter and an output signal of the adder. and vessels, the a first adaptive filter for inputting a sound signal, comprising a, is the output correction signal of the adaptive filter of the first type to the first source, the first coefficient updater is calculates and so that the output of the adder is reduced transmission, to update the coefficients of the first adaptive filter, the characteristics of the first filter, from the first source to the first detector Equivalent to function.
[0017]
In one embodiment, the second signal processing means includes a second filter that inputs an output signal of the first signal processing means, an output signal of the second filter, and an output of the second detector. wherein the second coefficient update unit for inputting the signal, a second adaptive filter for receiving the output signal of said first signal processing means comprises a control signal which is the output of the second adaptive filter input to the second source, the second coefficient updater is calculated by so that the output of the second detector is reduced, and updates the coefficient of the second adaptive filter, the second characteristic of the filter is equal to the transfer function of the to the second detector from the second sound source.
[0019]
According to the configuration of the loudspeaker of the present invention, the characteristic of the sound radiated from the first sound source can be set to a desired acoustic characteristic. Moreover, the directivity characteristic of the sound radiated from the first sound source can be changed by causing the sound radiated from the second sound source to interfere with the sound radiated from the first sound source.
[0020]
For example, the characteristics of sound radiated from the first sound source can be changed to desired acoustic characteristics at the position of the first detector.
[0021]
Further, the directivity characteristics of the sound radiated from the first sound source can be changed by causing the sound radiated from the first sound source to interfere with the sound radiated from the first sound source at the position of the second detector. .
[0022]
By appropriately setting the configuration of the signal generating means, the first sound source can emit a sound having the acoustic characteristics desired by the listener set by the signal correcting means, and a good sound environment can be obtained. It is done.
[0023]
In addition, by appropriately setting the configuration of the first signal processing means and / or the first signal processing means, the characteristics of the sound source and the sound field at the first detector position and / or the second detector position. Therefore, it is possible to radiate a sound having the acoustic characteristics desired by the listener set by the signal correction means without being influenced by the signal correction means, and a good sound environment can be obtained.
[0024]
In the configuration using the folded horn, the first sound source and the second sound source have a small change in the frequency of acoustic impedance, and the sound radiation has little disturbance in the sound pressure frequency characteristics, so that the size is small but good. Directivity and acoustic characteristics can be obtained. Further, by folding the horn, it is possible to suppress the entry of wind and rain into the driver horn.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0026]
(Embodiment 1)
FIG. 1 shows a first embodiment of the present invention and is a block diagram showing a configuration of a loudspeaker. 2 is a sound pressure frequency characteristic obtained by the first embodiment, and FIG. 3 is a directivity characteristic diagram obtained by the first embodiment.
[0027]
In FIG. 1, 1 is a signal generating means for outputting an acoustic signal, 2 is a first calculating means that outputs after processing the output signal of the signal generating means 1, and 3 is an output of the first calculating means 2. 2nd computing means that outputs after computing the signal, 4 is a first sound source that converts the output signal of the first computing means into sound, and 5 is an acoustic signal that is the output signal of the second computing means It is the 2nd sound source converted into.
[0028]
Hereinafter, the operation of the present embodiment will be described.
[0029]
The acoustic signal output from the signal generator 1 is input to the first calculator 2. The first computing means 2 performs at least one of delay control, amplitude control, and phase control on the input acoustic signal and outputs it. The first sound source 4 converts the output signal of the first computing means 2 into sound and radiates it. On the other hand, the second calculation means 3 receives the output signal of the first calculation means 2, performs at least one of delay control, amplitude control, and phase control and outputs the result. The second sound source 5 converts the output signal of the second calculation means 3 into sound and radiates it.
[0030]
In this configuration, by setting an arbitrary acoustic characteristic in the first computing means 2, the sound radiated from the first sound source 4 becomes a desired acoustic characteristic, and provides a good sound environment for the listener. be able to. Further, by setting an arbitrary acoustic characteristic in the second calculation means 3, the sound radiated from the first sound source 4 becomes a desired acoustic characteristic. Therefore, the sound radiated from the second sound source has a desired acoustic characteristic, and the directivity can be controlled by the interference with the sound radiated from the first sound source 4.
[0031]
For example, the first computing means 2 controls and outputs an acoustic signal so that the sound radiated from the first sound source 4 has a flat frequency characteristic in a frequency range of 300 Hz to 4 kHz, and the second computing means 3 in the sound emanating from the second sound source 5, the sound radiated from the first sound source 4 to reduce the front direction of the second sound source 5, and controls the first output signal of the operation unit 2 When output, the sound pressure frequency characteristic in the front direction of the first sound source 4 can obtain a flat frequency characteristic in a frequency range of 300 Hz to 4 kHz as shown in FIG. Moreover, the directivity characteristic of the synthesized sound by the sound radiated from the first sound source 4 and the second sound source 5 has a large acoustic radiation in the front direction of the first sound source 4 as shown in a of FIG. In the front direction of the second sound source 5 , it has a unidirectional characteristic shape having a small acoustic radiation.
[0032]
As described above, the first calculation unit 2 performs control based on the desired acoustic frequency characteristic, and the second calculation unit 3 performs control based on the desired directivity, as shown in the present embodiment. Sound characteristics and directivity can be obtained.
[0033]
In the present embodiment, the unidirectional characteristic is given as an example of the directional characteristic. However, the directional characteristic that can be formed is not limited to the unidirectional characteristic, and is controlled by the signal control by the second arithmetic unit 3. Needless to say, an arbitrary directivity characteristic can be formed by the radiated sound of the first sound source and the radiated sound of the second sound source.
[0034]
In the present embodiment, the second calculation means 3 inputs the output signal of the first calculation means 2, but the output signal of the signal generation means 1 is directly input to the second calculation means 3. Even if the second calculation means 3 performs the process considering the output signal of the first calculation means 2 on the output signal of the signal generation means 1 and outputs it, the same effect can be obtained. it is obvious.
[0035]
(Embodiment 2)
FIG. 4 shows a second embodiment of the present invention and is a block diagram showing a configuration of a loudspeaker.
[0036]
In FIG. 4, 6 is a first signal processing means for inputting an acoustic signal, 7 is an input of the acoustic signal, a delay device that outputs the acoustic signal after any delay control is applied thereto, and 8 is a first delaying device. A first detector installed in the vicinity of the sound source 4 to detect the radiated sound of the first sound source 4; 9 an adder for adding the output of the delay device 7 and the output signal of the first detector 8; 10 second signal processing means for receiving the output signal of the first signal processing means, 11 a second detector for detecting the radiated sound of the second sound source 5 installed in the vicinity of the second sound source 5 It is. Note that the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The same applies to the following embodiments.
[0037]
Hereinafter, the operation of the present embodiment will be described.
[0038]
An acoustic signal is input to the first signal processing means 6, and the output of the delay unit 7 set to a time substantially the same as the time required for the output is input to the adder 9. The adder 9 also receives the output signal of the first detector 8 that detects the radiated sound of the first sound source 4, performs an addition operation with the output signal of the delay device 7, and then performs first signal processing. Output to means 6. The first signal processing means 6 controls the output signal of the signal generating means 1 so that the output signal of the adder 9 becomes small, and outputs it to the first sound source 4 and the second signal processing means 10. The second detector 11 detects the radiated sound of the second sound source 5 and outputs it to the second signal processing means. The second signal processing means 10 first controls the output signal of the signal processing means so that the output signal of the second detector 11 becomes small, and outputs it to the second sound source 5 .
[0039]
With this configuration, the output of the adder 9 input to the first signal processing means 6 approaches zero. Therefore, when the acoustic signal that is the output signal of the signal generating means 1 is S, when the output signal of the adder 9 becomes zero, the output signal of the first detector 8 becomes -S, and the first detection A sound having the opposite phase and the same sound pressure as the acoustic signal is obtained at the position of the device 8. Therefore, by outputting an acoustic signal having an opposite phase to the desired acoustic characteristic by the signal generating means 1, a sound having the desired acoustic characteristic is emitted from the first sound source 4 at the position of the first detector 8. be able to.
[0040]
On the other hand, the output of the second detector 11 input to the second signal processing means 10 approaches zero. That is, the sound radiated from the first sound source 4 is canceled by the radiated sound of the second sound source 5 at the place where the second detector 11 is installed. Therefore, it is possible to form directional characteristics with less acoustic radiation in the direction in which the second detector 11 is installed.
[0041]
As described above, the first signal processing unit 6 and the second signal processing unit 10 control the radiated sounds of the first sound source 4 and the second sound source 5 as described in the present embodiment, so that the first Realizing the output signal of the signal generating means 1 that realizes the desired acoustic characteristics at the position of the first detector 8 and reducing the radiated sound from the sound sources 4 and 5 at the position of the second detector 11 Is possible. Therefore, it is possible to realize a loudspeaker that emits a good sound in a direction that requires sound and reduces sound emission in a direction that does not require sound.
[0042]
In the present embodiment, the first detector 8 and the second detector 11 are shown in the vicinity of the sound sources 4 and 5 , respectively. However, the positions of the detectors 8 and 11 are described above. It is not limited, and it goes without saying that the same effect can be obtained even if the acoustic characteristics are desired to be improved.
[0043]
Further, in the present embodiment, the case where the first detector 8 and the second detector 11 are installed has been described, but the processing contents of the first signal processing means 6 and the second signal processing means 10 are described. It is obvious that the same effect can be obtained without using either one or both of the first detector 8 and the second detector 11 when is unique to the input signal. Further, it is obvious that the same effect can be obtained even if the adder 9 and the delay unit 7 are not used in the same situation.
[0044]
(Embodiment 3)
FIG. 5 shows a third embodiment of the present invention and is a block diagram showing a configuration of the signal generating means 1.
[0045]
In FIG. 5, 12 is an acoustic signal source that outputs an electrical signal, and 13 is a signal correction unit that outputs at least one of amplitude control and phase control on the input electrical signal and then outputs it as an acoustic signal.
[0046]
Hereinafter, the operation of the present embodiment will be described.
[0047]
The acoustic signal source 12 is a device typified by a CD player, a cassette player, or the like, and outputs an electric signal of a desired sound. The electric signal output from the acoustic signal source 12 is input to the signal correction means 13. The signal correction unit 13 can arbitrarily control at least either amplitude control or phase control on the input signal, and outputs the sound signal after performing desired control on the input electric signal. To do.
[0048]
With this configuration, desired characteristics can be imparted to the acoustic signal output from the signal generation source 1. Therefore, as shown in the second embodiment, since the characteristic of the opposite phase to the acoustic signal can be realized at the position of the first detector, the sound having the desired acoustic characteristic is controlled by controlling the acoustic signal by the signal correction unit 13. Can be obtained at the position of the first detector.
[0049]
(Embodiment 4)
FIG. 6 shows a fourth embodiment of the present invention and is a block diagram showing a configuration of a loudspeaker.
[0050]
In FIG. 6, reference numeral 14 denotes an input of an acoustic signal, a first filter having a characteristic equal to the transfer characteristic between the first sound source 4 and the first detector 8, and 15 an output signal of the first filter 14. And a first coefficient updater for inputting the output signal of the adder 9, a first adaptive filter for inputting an acoustic signal, 17 for inputting an output signal of the first adaptive filter 16, and a second sound source. The second filter 18 has a characteristic equal to the transfer characteristic between the second detector 11 and the second detector 11, and a second filter 18 receives the output signal of the second filter 17 and the output signal of the second detector 11. The coefficient updater 19 is a second adaptive filter for inputting the output signal of the first adaptive filter 16.
[0051]
Hereinafter, the operation of the present embodiment will be described.
[0052]
The sound radiated from the first sound source 4 is detected by the first detector 8 and converted into an electric signal, and then input to the adder 9. In the adder 9, the acoustic signal output from the delay unit 7 and the output of the first detector 8 are added and output to the error input of the first coefficient updater 15. On the other hand, the output of the signal generating means 1 is input to the first adaptive filter 16 and the first filter 14, and the output signal of the first filter 14 is input to the reference input of the first coefficient updater 15. To do. The first coefficient updater 15 updates the coefficient of the first adaptive filter 16 by performing a coefficient update operation so that the error input is always reduced by an LMS (Least Mean Square) algorithm or the like.
[0053]
The output signal of the first adaptive filter 16 is input to the first sound source 4. If the transfer function from the first sound source 4 to the first detector 8 is C1, the characteristic of the first filter 14 is C1. When the first coefficient updater 15 is operated to converge the first adaptive filter 16, the output signal of the adder 9 approaches zero, and the first adaptive filter 16 converges to a characteristic of −1 / C1. Therefore, if the acoustic signal is S, the sound radiated from the first sound source 4 is -S / C1 . The sound radiated from the first sound source 4 is (−S / C1) · C1 = −S at the position of the first detector 8. Therefore, by installing the first detector 8 in the vicinity of the listening position, the listener can enjoy desired acoustic characteristics without being affected by the device and the sound field.
[0054]
If the transfer function from the first sound source 4 to the second detector 11 is G and the transfer function from the second sound source 5 to the second detector 11 is C2, the characteristics of the second filter 17 are as follows. C2. When the second coefficient updater 18 is operated to cause the second adaptive filter 19 to converge, the output signal of the second detector 11 approaches zero, and the second adaptive filter 19 has a characteristic of -G / C2. Converge. Accordingly, since the sound radiated from the first sound source 4 is -S / C1, the sound radiated from the first sound source 4 is (-S / C1) · G =-at the position of the second detector 11. On the other hand, the radiated sound of the second sound source 5 is (−S / C1) · (−G / C2) = (S · G) / (C1 · C2). Therefore, the radiated sound of the second sound source 5 is {(S · G) / (C1 · C2)} · C2 = S · G / C1 in the second detector 11, and the radiated sound of the first sound source 4 is obtained. And the radiated sound of the second sound source 5 interfere with each other at the position of the second detector 11, and (−S · G / C1) + (S · G / C1) = 0. Therefore, at the position of the second detector 11, the radiated sound of the first sound source 4 is canceled out by the radiated sound 5 of the second sound source 4, and the radiated sound of the first sound source 4 is emitted from the second detector 11. Directional characteristics with the least acoustic radiation in the direction.
[0055]
As described above, as shown in the present embodiment, by operating the first adaptive filter 16 and the second adaptive filter 19, it is possible to realize a good acoustic characteristic of the radiated sound in the first detector 8. Thus, it is possible to simultaneously reduce the radiation sound by the second detector 11.
[0056]
In the present embodiment, the case where the first filter 14, the first coefficient updater 15, the second filter 17, and the second coefficient updater 18 are operated has been described. However, the first adaptive filter 16 And the second adaptive filter 19 are unique to the input signal, the first filter 14, the first coefficient updater 15, the second filter 17, and the second coefficient updater 18. It is clear that the same effect can be obtained even if the operation of is stopped. Further, it is obvious that the same effect can be obtained for the adder 9 and the delay device 7 even if they are not used in the same situation. Also, the same effect can be obtained by realizing the processing contents of the first adaptive filter 16 and the second adaptive filter 19 obtained in such a situation by a simple method such as a fixed filter. it is obvious.
[0057]
(Embodiment 5)
7 and 8 show Embodiment 5 of the present invention, and FIG. 7 shows the configuration of a sound source used for one or both of the first sound source 4 and the second sound source 5. FIG. 8 shows a configuration when the fifth embodiment is applied to both the first sound source 4 and the second sound source 5.
[0058]
7 and 8, 20 is a folded horn that has been folded three times, 21 is a horn driver, 22 is an acoustic radiation surface that is the open end of the folded horn 20, and b is the entire length of the folded horn 20.
[0059]
In FIG. 7, the sound radiated from the horn driver 21 is guided inside the folded horn 20 in the direction of the arrow, and is radiated to the outside with the directivity controlled. With this configuration, the cross-sectional area perpendicular to the sound wave traveling direction (arrow) of the folded horn 20 can be smoothly changed without increasing the horn length b. Accordingly, the folded horn 20 has a small change in frequency of acoustic impedance, and the sound radiation from the folded horn 20 is less disturbed by the sound pressure frequency characteristics, so that good directivity characteristics and acoustic characteristics can be obtained although the dimensions are small. be able to. Furthermore, by having the folded structure, as shown in FIG. 8, the first sound source 4 and the second sound source 5 shorten the distance between the acoustic radiation surfaces 22 that are the open ends of the folded horn 20. Therefore, higher frequency directivity control is possible. Moreover, the invasion of wind and rain into the horn driver 21 can be suppressed by folding the horn.
[0060]
In the fifth embodiment, an example is shown in which the folding horn 20 is folded three times, but the folding horn 20 is folded once, twice, four times, five times,... Needless to say, the same effect can be obtained even when the number of times is set to other times such as n times.
[0061]
【The invention's effect】
As described above, according to the loudspeaker according to the present invention, by arranging a plurality of sound sources and controlling the radiated sound, the desired acoustic characteristics and radiated sound reduction can be achieved by mutual interference at the listening position. A loudspeaker having directivity characteristics that does not radiate a loud sound in an area that does not require a loud sound while providing a loud sound having a good acoustic characteristic in an area that requires a loud sound is provided. It becomes possible to do.
[0062]
Further, by using a folding horn as a sound source, the sound characteristics of the sound source itself can be improved, and at the same time, the apparatus can be downsized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a loudspeaker according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing sound pressure frequency characteristics obtained by the loudspeaker according to Embodiment 1 of the present invention.
FIG. 3 is a directional characteristic diagram obtained by the loudspeaker according to the first embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of a loudspeaker according to Embodiment 2 of the present invention.
FIG. 5 is a block diagram showing a configuration of signal generating means in Embodiment 3 of the present invention.
FIG. 6 is a block diagram showing a configuration of a loudspeaker according to Embodiment 4 of the present invention.
FIG. 7 is a diagram showing a configuration of a sound source in the fifth embodiment of the present invention.
FIG. 8 is a diagram showing a configuration of a sound source in the fifth embodiment of the present invention.
FIG. 9 is a diagram showing a configuration of a conventional loudspeaker.
FIG. 10 is a diagram showing a configuration of a conventional loudspeaker.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Signal generating means 2 1st calculating means 3 2nd calculating means 4 1st sound source 5 2nd sound source 6 1st signal processing means 7 Delay device 8 1st detector 9 Adder 10 2nd signal Processing means 11 second detector 12 acoustic signal source 13 signal correction means 14 first filter 15 first coefficient updater 16 first adaptive filter 17 second filter 18 second coefficient updater 19 second Adaptive filter 20, 26 Folded horn 21, 23 Horn driver 22, 25 Acoustic radiation surface 24 Horn

Claims (3)

A first sound source and a second sound source;
Signal generating means for outputting an acoustic signal;
A delay device that receives the acoustic signal and outputs a delay time to the input acoustic signal;
A first detector that is installed in the vicinity of the first sound source, detects the sound emitted by the first sound source and the second sound source , converts the sound into an electrical signal, and outputs the electrical signal;
An adder that receives the output signal of the first detector and the output signal of the delay device, adds the output signal of the first detector and the output signal of the delay device, and outputs the sum;
First signal processing means for inputting the acoustic signal and an output signal of the adder, and outputting a correction signal such that the output signal of the adder becomes small with respect to the acoustic signal;
A second detector that is installed in the vicinity of the second sound source, detects the sound emitted by the first sound source and the second sound source, converts the sound into an electrical signal, and outputs the electrical signal;
An output signal of the first signal processing means is input, and a control signal that makes the output signal of the second detector smaller than the output signal of the first signal processing means is given to the second sound source. Second signal processing means for outputting to
With
The output signal of the first signal processing means is input to the first sound source,
The first sound source and the second sound source include a horn driver that converts an acoustic signal from an acoustic signal source into air vibration, and a wave front of air vibration output from the horn driver toward a traveling direction of the sound wave. It consists of a horn that changes to
The horn drivers of the first sound source and the second sound source are arranged so that acoustic radiation faces each other,
The loudspeaker according to claim 1, wherein the horn is folded an odd number of times. The first signal processing means includes
A first filter for inputting the acoustic signal;
A first coefficient updater for inputting the output signal of the first filter and the output signal of the adder;
A first adaptive filter for inputting the acoustic signal;
With
A correction signal that is an output of the first adaptive filter is input to the first sound source;
The first coefficient updater calculates the output of the adder to be small and updates the coefficient of the first adaptive filter,
The loudspeaker according to claim 1, wherein a characteristic of the first filter is equal to a transfer function from the first sound source to the first detector. The second signal processing means includes
A second filter for inputting an output signal of the first signal processing means;
A second coefficient updater for inputting the output signal of the second filter and the output signal of the second detector;
A second adaptive filter for inputting an output signal of the first signal processing means;
With
A control signal which is an output of the second adaptive filter is input to the second sound source;
The second coefficient updater calculates the output of the second detector to be small, and updates the coefficient of the second adaptive filter,
The loudspeaker according to claim 2, wherein a characteristic of the second filter is equal to a transfer function from the second sound source to the second detector.

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