Adaptive Filter Noise Reference Signal Generation
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Solution Overview
Problem
Existing noise compensation and reduction methods in acoustic signals, such as those used in speech processing, often fail to produce accurate noise reference signals due to low correlation between noise components from multiple microphones, leading to impaired signal quality and increased misrecognitions, especially in environments with strong reflecting boundaries causing comb-filter effects.
Innovation Solution
The method employs two adaptive filters to combine audio signals from multiple microphones, minimizing the wanted signal component in the noise reference signal by approximating room transfer functions and using a normalized least mean square method or signal-to-noise ratio minimization criteria, even in the presence of comb-filter effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two microphones are placed close to each other to increase noise component correlation, then the noise reference signal quality improves, but the wanted signal component in the noise reference signal increases
Solution Approach 1:
The patent extracts the wanted signal component from the noise reference signal by using a blocking matrix that processes the microphone signals. The blocking matrix is designed to block the wanted signal while allowing the noise component to pass through, thereby obtaining a clean noise reference signal for interference cancellation.
Solution Approach 2:
The blocking matrix serves as an intermediary device between the microphones and the interference canceller. It processes the raw microphone signals to generate a noise reference signal that has had the unwanted wanted signal component removed, enabling effective noise cancellation without contaminating the reference signal.
2Object-generated harmful factors
If a blocking matrix is used to remove wanted signal component from the noise reference signal, then the wanted signal blocking improves, but the system complexity increases
Solution Approach 1:
The blocking matrix uses adaptive filtering techniques where the filter coefficients are dynamically adjusted based on the input signals. This allows the system to adapt to changing acoustic environments and optimize the blocking of wanted signals while maintaining noise reference signal quality, rather than using fixed complex structures.
Solution Approach 2:
The system changes parameters such as filter coefficients and adaptation step sizes to optimize performance. By dynamically adjusting these parameters based on signal conditions, the system achieves effective wanted signal blocking without requiring a permanently complex structure, reducing overall system complexity while maintaining effectiveness.
Data Source
AI summary
The invention provides a method for determining a noise reference signal for noise compensation and/or noise reduction. A first audio signal on a first signal path and a second audio signal on a second signal path are received. The first audio signal is filtered using a first adaptive filter to obtain a first filtered audio signal. The second audio signal is filtered using a second adaptive filter to obtain a second filtered audio signal. The first and the second filtered audio signal are combined to obtain the noise reference signal. The first and the second adaptive filter are adapted such as to minimize a wanted signal component in the noise reference signal.