Dynamic Audio Distortion Suppression for Speakerphone Timbre Control
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Solution Overview
Problem
Conventional methods for reducing non-linear distortion in audio devices, such as speakerphones, often degrade audio quality by suppressing signals at lower loudness levels unnecessarily or applying aggressive limiting, which can lead to echo leakage and timbre degradation.
Innovation Solution
A dynamic suppression system that uses multi-band limiter and dynamic shelf filters to analyze and adjust the audio signal's spectrum based on non-linear distortion, preserving timbre and reducing distortion without unnecessary suppression across varying volume levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods apply aggressive limiting to reduce non-linear distortion, then distortion is reduced, but audio quality degrades due to echo leakage and timbre degradation
Solution Approach 1:
The system dynamically adjusts the limiting threshold based on the detected distortion level. When distortion exceeds a threshold, limiting is applied; when distortion is low, limiting is reduced or removed. This dynamic adaptation prevents aggressive limiting during low-distortion periods, preserving audio quality and timbre while still suppressing distortion when necessary.
Solution Approach 2:
The system changes the operating parameters of the limiter based on real-time distortion measurements. The limiting threshold and attack/release times are adjusted according to the detected distortion level, allowing the system to optimize between distortion suppression and audio quality preservation under different operating conditions.
2Reliability
If conventional methods apply continuous suppression to reduce non-linear distortion, then distortion is reduced, but audio quality degrades at lower loudness levels due to unnecessary suppression
Solution Approach 1:
The system transitions from static continuous suppression to dynamic conditional suppression. The limiter is actively engaged only when distortion measurements exceed a predefined threshold, allowing the system to maintain high audio quality during low-distortion conditions (including lower loudness levels) while effectively suppressing distortion when it becomes problematic.
Solution Approach 2:
The system uses feedback from real-time distortion measurement to control the limiter engagement. The distortion detector continuously monitors the audio signal and provides feedback that modulates the limiter's operation, ensuring suppression is applied only when actually needed rather than continuously.
3Ease of operation
If a multi-band limiter is used to dynamically suppress distortion, then audio quality is preserved, but device complexity increases
Solution Approach 1:
The audio signal is divided into multiple frequency bands, with separate limiters applied to each band. This segmentation allows targeted distortion suppression in specific frequency ranges where distortion is most problematic, while preserving audio quality in other bands, thereby reducing the overall complexity compared to applying aggressive full-band limiting.
Data Source
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AI summary
Systems and methods are described for dynamically suppressing non-linear distortion for a device, such as a speakerphone. A device may receive a signal, where the device has non-linear distortion at a predetermined frequency. The received signal may be analyzed to compute a tone strength parameter and a band level. The received signal may be filtered such that a spectrum of the input signal is dynamically limited by reducing suppression of the non-linear distortion when the tone strength parameter is in a lower portion of a predetermined range and increasing suppression of the non-linear distortion when the tone strength parameter is in an upper portion of the predetermined range, the predetermined range of the tone strength parameter corresponding to a loudness range of the device.