Micro-Loudspeaker Distortion Sensing for Adaptive Bass Enhancement
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Solution Overview
Problem
Micro-loudspeakers in consumer devices face challenges with reduced low-frequency response and distortion issues, such as 'rub and buzz' distortion, due to their small size and the need for significant equalization, which can lead to over-excursion and mechanical issues, and existing solutions fail to accurately address these problems.
Innovation Solution
A system employing dynamic multi-feature distortion sensing and adaptive multi-band distortion reduction using a bank of notch or band-reject filters, combined with distortion-aware harmonic bass enhancement, to quantify and mitigate distortion in real-time, while maintaining audio quality and minimizing timbre impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flattening equalization is applied to improve low-frequency response, then audio quality is improved, but distortion increases due to over-excursion
Solution Approach 1:
The patent implements dynamic equalization that adapts to real-time signal conditions and speaker excursion limits. The system continuously monitors the input signal characteristics and adjusts equalization parameters dynamically, switching between different equalization curves based on the current operating point to prevent over-excursion while maintaining audio quality.
Solution Approach 2:
The system uses excursion-based feedback mechanisms where the equalization is guided by a loudspeaker excursion model. The feedback loop monitors speaker displacement and adjusts the equalization accordingly, reducing the equalization engagement when excursion limits are approached to prevent distortion.
2Reliability
If multi-tonal signals are processed through flattening equalization, then frequency response is improved, but rub and buzz distortion occurs
Solution Approach 1:
The patent employs dynamic equalization that responds to the specific characteristics of multi-tonal signals. The system analyzes the spectral content and temporal patterns of the input signal, adjusting equalization parameters in real-time to prevent the interaction between multiple frequencies that causes rub and buzz distortion.
Solution Approach 2:
The system changes equalization parameters based on the detected signal type and operating conditions. Different equalization curves are selected based on the signal characteristics, and parameters such as cutoff frequencies, gain levels, and filter Q-factors are adjusted dynamically to prevent distortion in multi-tonal scenarios.
3Reliability
If excursion models are used to guide time-varying equalization, then over-excursion is prevented, but the models are blind to distortion-causing circumstances
Solution Approach 1:
The patent segments the distortion analysis into multiple independent features that are processed separately. Instead of relying on a single excursion model, the system divides the signal into different frequency bands and analyzes distortion characteristics in each band independently, then combines the results to achieve comprehensive distortion detection.
Solution Approach 2:
The system changes the measurement parameters used for distortion detection based on the operating conditions. Different statistical features and spectral analysis methods are employed depending on the signal type and speaker operating point, allowing the system to detect distortion causes that excursion models alone would miss.
Data Source
AI summary
Systems and methods to provide distortion sensing, prevention, and/or distortion-aware bass enhancement in audio systems can be implemented in a variety of applications. Sensing circuitry can generate statistics based on an input signal received for which an acoustic output is generated. In various embodiments, the statistics can be used such that a multi-notch filter can be used to provide input to a speaker to generate the acoustic output. In various embodiments, the statistics from the sensing circuitry can be provided to a bass parameter controller coupled to bass enhancement circuitry to operatively provide parameters to the bass enhancement circuitry. The bass enhancement circuitry can provide a bass enhanced signal for generation of the acoustic output, based on the parameters. Various combinations of a multi-notch filter and bass enhancement circuitry using statistics from sensing circuitry can be implemented to provide an enhanced acoustic output. Additional apparatus, systems, and methods are disclosed.