Frequency-Dependent Attenuation Tuning for Audio Distortion Control
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Solution Overview
Problem
Audio reproduction systems suffer from non-linear distortion, which affects sound quality by changing timbre and phase with sound amplitude, and current methods to suppress this often compromise loudness or introduce timbral changes.
Innovation Solution
A device and method for tuning a frequency-dependent attenuation stage that detects non-linear distortion and applies psycho-acoustic compensation to control the attenuation stage, ensuring efficient suppression of perceptible distortion while maintaining overall loudness, using techniques like psycho-acoustic modeling and dynamic range control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dynamic range limiter is used to suppress non-linear distortion, then distortion is reduced, but system loudness is sacrificed
Solution Approach 1:
The audio signal is divided into multiple frequency bands, and limiting is applied independently to each band. This allows selective attenuation of only those frequency components that exhibit non-linear distortion, preserving loudness in frequency bands that remain linear.
Solution Approach 2:
Different limiting thresholds and compression ratios are applied to different frequency bands based on their individual distortion characteristics. Frequency bands with severe distortion receive stronger limiting, while cleaner bands maintain higher gain, creating locally optimized distortion suppression.
2Object-affected harmful factors
If multi-band limiting is applied to suppress distortion in specific frequency bands, then distortion is reduced, but timbral changes occur
Solution Approach 1:
The limiting parameters (thresholds, ratios, attack, release) are made dynamic and adaptive, automatically adjusting based on the measured distortion level of each frequency band. This allows the system to apply stronger limiting only when and where distortion is detected, preserving natural timbre during clean passages.
Solution Approach 2:
The system continuously monitors the output signal for non-linear distortion and uses this feedback to dynamically adjust the limiting parameters of each frequency band. This closed-loop control ensures distortion suppression while minimizing impact on the original signal characteristics.
Data Source
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AI summary
A device (160) and a method are proposed for tuning a frequency-dependent attenuation stage (122),with the purpose of suppressing non-linear distortion occurring in an audio reproduction system (120) associated with the frequency- dependent attenuation stage. The device comprises a receiving section (162) adapted to receive data (161) representing an output acoustic signal (140) from the audio reproduction system,recorded upon excitation of the audio reproduction system by a predetermined input data signal(110)a first distortion detection section (163) adapted to detect presence of non-linear distortion based on the received data and to apply psycho-acoustic compensation to the detected non-linear distortion and a control section (164) adapted to determine, based on the psycho-acoustically compensated non-linear distortion, control information (170) suitable for controlling the frequency-dependent attenuation stage.