NOISE CONTROLLER, NOISE CONTROLLING METHOD, AND RECORDING MEDIUM
First Claim
1. A noise controller comprising:
- a noise detector that detects a noise generated by a noise source;
a control filter that performs signal processing on a noise signal indicative of the noise detected by the noise detector, using a predetermined control factor;
a speaker that reproduces an output signal from the control filter, as a control sound;
an error microphone that is disposed at a control point where interference between the noise propagated from the noise source and the control sound reproduced by the speaker occurs, and detects a residual noise that is left at the control point as a result of the interference;
a transmission characteristics correction filter that performs signal processing on the noise signal, using characteristics of sound transmission from the speaker to the error microphone;
a factor updater that updates the control factor to minimize an error signal, using the error signal indicative of the residual noise detected by the error microphone and an output signal from the transmission characteristics correction filter;
a correction filter that performs signal processing on an output signal from the control filter, using the characteristics of sound transmission from the speaker to the error microphone;
a subtractor that subtracts, from the error signal, an output signal from the correction filter; and
an effect measuring unit that processes an output signal from the subtractor as a control-off signal representing a noise not yet subjected to control by the interference and processes the error signal as a control-on signal representing a noise having been subjected to control by the interference, and measures a noise reduction effect at the control point based on a difference between the control-off signal and the control-on signal.
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Accused Products
Abstract
A noise controller includes: a noise detector; a control filter that performs signal processing on a noise signal using a control factor; a speaker that reproduces an output signal from the control filter; an error microphone that detects a residual noise at a control point; a transmission characteristics correction filter that performs signal processing on the noise signal, using characteristics of sound transmission from the speaker to the error microphone; a factor updater that updates the control factor; a correction filter that performs signal processing on an output signal from the control filter, using the characteristics of sound transmission; a subtractor that subtracts, from an error signal indicative of the residue noise, an output signal from the correction filter; and an effect measuring unit that measures a noise reduction effect at the control point based on a difference between an output signal from the subtractor and the error signal.
9 Citations
19 Claims
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1. A noise controller comprising:
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a noise detector that detects a noise generated by a noise source; a control filter that performs signal processing on a noise signal indicative of the noise detected by the noise detector, using a predetermined control factor; a speaker that reproduces an output signal from the control filter, as a control sound; an error microphone that is disposed at a control point where interference between the noise propagated from the noise source and the control sound reproduced by the speaker occurs, and detects a residual noise that is left at the control point as a result of the interference; a transmission characteristics correction filter that performs signal processing on the noise signal, using characteristics of sound transmission from the speaker to the error microphone; a factor updater that updates the control factor to minimize an error signal, using the error signal indicative of the residual noise detected by the error microphone and an output signal from the transmission characteristics correction filter; a correction filter that performs signal processing on an output signal from the control filter, using the characteristics of sound transmission from the speaker to the error microphone; a subtractor that subtracts, from the error signal, an output signal from the correction filter; and an effect measuring unit that processes an output signal from the subtractor as a control-off signal representing a noise not yet subjected to control by the interference and processes the error signal as a control-on signal representing a noise having been subjected to control by the interference, and measures a noise reduction effect at the control point based on a difference between the control-off signal and the control-on signal. - View Dependent Claims (2, 3, 4, 6, 7, 8, 10, 11, 14, 15, 16)
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5. The noise controller according to claim I, wherein the effect measuring unit includes
a frequency analyzer that calculates frequency characteristics of the control-off signal and the control-on signal, and a frequency difference effect calculating unit that, for each frequency making up the frequency characteristics, calculates a first difference representing a difference between the control-off signal and the control-on signal, as an index for the noise reduction effect.
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17. A noise control method performed by a computer of a noise controller, the noise control method comprising:
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detecting a noise generated by a noise source, using a sensor; performing first signal processing on a noise signal indicative of the noise detected by the sensor, using a predetermined control factor; causing a speaker to reproduce a signal resulting from the first signal processing, as a control sound; detecting a residual noise that is left at a control point as a result of interference, using an error microphone disposed at the control point where the interference between the noise propagated from the noise source and the control sound reproduced by the speaker occurs; performing second signal processing on the noise signal, using characteristics of sound transmission from the speaker to the error microphone; updating the control factor to minimize an error signal, using the error signal indicative of the residual noise detected by the error microphone and a signal resulting from the second signal processing; performing third signal processing on a signal resulting from the first signal processing, using the characteristics of sound transmission from the speaker to the error microphone; subtracting, from the error signal, a signal resulting from the third signal processing; and processing a signal given by subtraction as a control-off signal representing a noise not yet subjected to control by the interference and processing the error signal as a control-on signal representing a noise having been subjected to control by the interference, and measuring a noise reduction effect at the control point based on a difference between the control-off signal and the control-on signal. - View Dependent Claims (18)
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19. A noise controller comprising:
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a noise detector that detects a noise generated by a noise source; a control filter that performs signal processing on a noise signal indicative of the noise detected by the noise detector, using a predetermined control factor; a speaker that reproduces an output signal from the control filter, as a control sound; an error microphone that is disposed at a control point where interference between the noise propagated from the noise source and the control sound reproduced by the speaker occurs, and detects a residual noise that is left at the control point as a result of the interference; a correction filter that performs signal processing on an output signal from the control filter, using characteristics of sound transmission from the speaker to the error microphone; a subtractor that subtracts, from the error signal, an output signal from the correction filter; and an effect measuring unit that processes an output signal from the subtractor as a control-off signal representing a noise not yet subjected to control by the interference and processes the error signal as a control-on signal representing a noise having been subjected to control by the interference, and measures a noise reduction effect at the control point based on a difference between the control-off signal and the control-on signal.
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Specification