Hearing Aid Adaptive Filter Artefact Reduction

The patent applies preliminary action by pre-defining a space of valid filter coefficients through prior covariance matrices before adaptive filtering occurs. This constrains the adaptive filter to operate within predetermined bounds, preventing it from selecting coefficient values that would generate artefacts during sudden signal changes. The prior covariance matrix establishes acceptable filter states in advance, so when rapid changes occur, the filter remains within reliable operating parameters rather than drifting into artefact-prone regions.

The patent utilizes parameter changes by dynamically adjusting the covariance matrices based on signal statistics. When sudden changes in input signals are detected, the system modifies the prior and transition covariance matrices to reflect current signal characteristics. This adaptive parameter adjustment allows the filter to respond to changing conditions while maintaining coefficient values within ranges that minimize artefact generation, thus improving signal processing quality during transient events.

The patent implements dynamics by making the covariance matrices adaptive rather than static. The prior covariance matrix is updated based on current signal statistics, allowing the filter to dynamically adjust its constraints. During rapid sound changes, the system increases the adaptability parameters, enabling faster response. However, this dynamic adjustment occurs within the framework of the space of valid coefficients, ensuring that even during rapid adaptation, the filter coefficients remain within bounds that prevent artefact generation.

The patent employs feedback mechanisms by continuously monitoring signal statistics and using this information to update the covariance matrices. The system measures the actual signal characteristics and feeds this information back to adjust the prior and transition covariance matrices accordingly. This closed-loop approach allows the filter to respond quickly to sound environment changes while using the feedback information to maintain coefficient values within artefact-free regions, thus resolving the contradiction between speed and artefact prevention.

The patent resolves this contradiction through dynamics by making the constraints themselves adaptive. The prior covariance matrix, which defines the space of valid filter coefficients, is not fixed but is updated based on signal statistics. During periods of rapid sound changes, the covariance matrix expands to allow greater coefficient variation, maintaining adaptability. During stable periods, the constraints are tighter, reducing artefacts. This dynamic constraint adjustment allows the system to maintain both artefact reduction and filter adaptability across different operating conditions.

The patent applies parameter changes by modifying the covariance matrix parameters in response to signal characteristics. When the system detects rapid changes in sound environments, it adjusts the covariance parameters to allow a broader space of valid coefficients, thereby maintaining adaptability. When signals are stable, the parameters are adjusted to constrain the coefficient space more tightly, reducing artefacts. This parameter adaptation ensures that the filter maintains optimal performance across varying conditions without sacrificing either adaptability or artefact prevention.