Active Noise Control Apparatus with Adaptive Amplitude Suppression
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Solution Overview
Problem
Existing active noise control apparatuses face challenges in effectively canceling road noise due to unpredictable amplitude changes, leading to clipping of canceling signals and reduced noise reduction capability, especially when the sum of amplitudes exceeds the mixer's output range.
Innovation Solution
Incorporating an amplitude suppressor that adjusts the amplitude of one canceling signal based on another, using adaptive notch filters and a noise reduction priority sequence to optimize the output range of the mixer, preventing clipping by suppressing lower-priority noise signals when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output range of the mixer is divided into equal subranges for multiple canceling signals, then the system can handle multiple noise types, but the canceling signal with large amplitude becomes clipped when the sum exceeds the mixer output range
Solution Approach 1:
The patent applies dynamics by making the subrange assignment adaptive rather than fixed. The amplitude suppressor dynamically adjusts which noise type receives the full output range based on real-time amplitude comparisons. When road noise amplitude exceeds engine noise amplitude, the system switches subrange assignments to prioritize road noise cancellation, ensuring optimal performance for the dominant noise source while maintaining versatility for handling multiple noise types.
2Device complexity
If equal subranges are assigned to each canceling signal, then the system structure is simple, but the road noise cancelation performance deteriorates when road noise magnitude changes greatly
Solution Approach 1:
The system transitions from a static equal subrange assignment to a dynamic adaptive assignment. The amplitude suppressor continuously monitors the amplitudes of different noise types and dynamically reallocates the mixer's output range. When road noise becomes the dominant noise source, the system automatically assigns the full output range to the road noise canceling signal, ensuring reliable cancelation performance despite varying road conditions without increasing hardware complexity.
3Reliability
If the mixer output range is fully utilized for one noise type, then that noise type achieves optimal cancelation, but other noise types suffer from reduced output range and potential clipping
Solution Approach 1:
The system implements dynamic priority-based resource allocation. The amplitude suppressor compares amplitudes of different noise types in real-time and dynamically assigns the full mixer output range to the dominant noise type. This dynamic switching mechanism ensures that whichever noise type is most prominent at any given moment receives optimal cancelation resources, while maintaining the system's ability to handle multiple noise types by switching priorities as conditions change.
Data Source
AI summary
An active noise control apparatus includes a first active noise controller for generating a first canceling signal for a first noise type, a second active noise controller for generating a second canceling signal for a second noise type that is different from the first noise type, a mixer for mixing the first canceling signal and the second canceling signal into a mixed canceling signal, a canceling sound output unit for outputting a canceling sound based on the mixed canceling signal, and an amplitude suppressor for suppressing the amplitude of the second canceling signal depending on the amplitude of the first canceling signal.