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US 9,318,093 B2Granted
Active noise-reduction apparatus and method
AssigneeKabushiki Kaisha Toshiba
InventorTatsuhiko Goto
Life of this patent
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Abstract
According to an embodiment, an active noise-reduction apparatus includes following elements. The microphone converts a sound including a target sound into an error signal. The control filter generates a control signal in accordance with a control characteristic. The first control effect estimation filter converts the control signal into a first signal in accordance with an estimated secondary path characteristic. The second control effect estimation filter converts the control signal into a second signal in accordance with a processed secondary path characteristic obtained by shortening a delay of the estimated secondary path characteristic. The updating unit updates the control characteristic based on the error signal, the first signal, and the second signal.
Claims16
An active noise-reduction apparatus for reducing a target sound having periodicity, the apparatus comprising:
- an error microphone which converts a sound including the target sound into a first error signal;
- a reference signal generator configured to generate a reference signal;
- a control filter configured to convert, in accordance with a control characteristic, the reference signal into a control signal used to cancel the target sound;
- a control loudspeaker which emits a control sound based on the control signal;
- a first control effect estimation filter configured to convert the control signal into a first signal in accordance with an estimated secondary path characteristic, the estimated secondary path characteristic being generated based on a result of identifying a secondary path characteristic from the control loudspeaker to the error microphone in advance;
- an estimated noise signal generator configured to generate an estimated noise signal by subtracting the first signal from the first error signal;
- a second control effect estimation filter configured to convert the control signal into a second signal in accordance with a processed secondary path characteristic, the processed secondary path characteristic being obtained by shortening a delay included in the estimated secondary path characteristic by a time, the time corresponding to a period of the target sound multiplied by a constant;
- and
- an updating unit configured to update the control characteristic so that a second error signal which is a sum of the estimated noise signal and the second signal is minimized,
- wherein letting T be the period, a be the delay, and m be the constant, the constant is a positive integer satisfying T×m≦a.
7 more elements
An active noise-reduction apparatus for reducing a target sound, the apparatus comprising:
- an error microphone which converts a sound including the target sound into an error signal;
- a reference signal generator configured to generate a reference signal;
- a control filter configured to convert, in accordance with a control characteristic, the reference signal into a control signal used to cancel the target sound;
- a control loudspeaker which emits a control sound based on the control signal;
- a control effect estimation filter configured to convert the control signal into a first signal in accordance with an estimated secondary path characteristic, the estimated secondary path characteristic generated based on a result of identifying a secondary path characteristic from the control loudspeaker to the error microphone in advance;
- a secondary path filter configured to convert the reference signal into a first auxiliary signal in accordance with the estimated secondary path characteristic;
- a virtual control effect estimation filter configured to convert the first auxiliary signal into a second signal in accordance with the control characteristic;
- and
- an updating unit configured to update the control characteristic so that an evaluation function based on the error signal and a second auxiliary signal is minimized, the second auxiliary signal being a difference between the second signal and the first signal.
6 more elements
An active noise-reduction method for reducing a target sound having periodicity, the method comprising:
- providing an error microphone which converts a sound including the target sound into a first error signal;
- generating a reference signal;
- converting, in accordance with a control characteristic, the reference signal into a control signal used to cancel the target sound;
- providing a control loudspeaker which emits a control sound based on the control signal;
- converting the control signal into a first signal in accordance with an estimated secondary path characteristic, the estimated secondary path characteristic being generated based on a result of identifying a secondary path characteristic from the control loudspeaker to the error microphone in advance;
- generating an estimated noise signal by subtracting the first signal from the first error signal;
- converting the control signal into a second signal in accordance with a processed secondary path characteristic, the processed secondary path characteristic being obtained by shortening a delay included in the estimated secondary path characteristic by a time, the time corresponding to a period of the target sound multiplied by a constant;
- and
- updating the control characteristic so that a second error signal which is a sum of the estimated noise signal and the second signal is minimized,
- wherein letting T be the period, a be the delay, and m be the constant, the constant is a positive integer satisfying T×m≦a.
7 more elements
An active noise-reduction method for reducing a target sound, the method comprising:
- providing an error microphone which converts a sound including the target sound into an error signal;
- generating a reference signal;
- converting, in accordance with a control characteristic, the reference signal into a control signal used to cancel the target sound;
- providing a control loudspeaker which emits a control sound based on the control signal;
- converting the control signal into a first signal in accordance with an estimated secondary path characteristic, the estimated secondary path characteristic generated based on a result of identifying a secondary path characteristic from the control loudspeaker to the error microphone in advance;
- converting the reference signal into a first auxiliary signal in accordance with the estimated secondary path characteristic;
- converting the first auxiliary signal into a second signal in accordance with the control characteristic;
- and
- updating the control characteristic so that an evaluation function based on the error signal and a second auxiliary signal is minimized, the second auxiliary signal being a difference between the second signal and the first signal.
6 more elements
Dependencies are inferred from the claim text.