Audio Gain Control Using Echo and Noise Reduction Feedback
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Solution Overview
Problem
Electronic devices face challenges in processing audio data due to the presence of echo and noise, which degrade the quality of communication by generating audio data that includes more than just user speech, leading to reduced audio quality.
Innovation Solution
An audio processing pipeline is employed that includes an automatic gain controller (AGC) using algorithms to normalize audio data, a voice activity detector (VAD) for mode switching, a residual echo suppressor (RES) for echo suppression, and a noise estimator/reductor for noise reduction, along with a dynamic range compressor, to improve audio quality by determining and adjusting gains based on energy values and confidence levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If audio data is processed using a simple pipeline without echo suppression and noise reduction, then device complexity is reduced, but audio quality deteriorates due to presence of echo and noise
Solution Approach 1:
The audio processing pipeline is divided into distinct functional modules: echo suppressor module, noise reduction module, and automatic gain controller module. Each module handles a specific aspect of audio quality improvement, allowing the system to address multiple harmful factors (echo and noise) through specialized processing stages rather than a single complex operation
Solution Approach 2:
The echo suppressor performs preliminary processing by removing echo components from the audio data before the noise reduction module operates. This sequential preliminary action ensures that each processing stage works on progressively cleaner audio signals, improving overall audio quality while maintaining manageable complexity through organized preprocessing steps
2Object-affected harmful factors
If echo suppression and noise reduction processing is applied, then audio quality is improved, but processing time increases
Solution Approach 1:
The automatic gain controller applies gain adjustments selectively based on detected speech activity and noise levels rather than uniformly processing all audio data. The controller modifies processing intensity according to actual conditions, applying stronger processing only when necessary to maintain audio quality while reducing processing time during periods when less intervention is needed
Solution Approach 2:
The automatic gain controller continuously monitors the audio signal characteristics and adjusts processing parameters in real-time based on feedback from the audio data. This closed-loop control allows the system to adapt processing intensity to actual audio conditions, optimizing the balance between audio quality improvement and processing time consumption
3Manufacturing precision
If automatic gain control with mode switching is implemented, then audio energy normalization is improved, but device complexity increases
Solution Approach 1:
The automatic gain controller implements dynamic mode switching between different operating modes based on real-time analysis of audio signal characteristics. The controller transitions between modes (such as echo suppression mode, noise reduction mode, and gain adjustment mode) to optimize processing for different audio conditions, achieving precise gain control while adapting to varying operational requirements
Data Source
AI summary
This disclosure describes, in part, techniques for processing audio data. For instance, an electronic device may include an automatic gain controller (AGC) that determines AGC gains for amplifying or attenuating an audio data. To determine the AGC gains, the AGC uses information from a residual echo suppressor (RES) and/or a noise reductor (NR). The information may indicate RES gains applied to the audio data by the RES and/or NR gains applied to the audio data by the NR. In some instances, to determine the AGC gain, the AGC determines time-constant parameter(s) using the information. The AGC then uses the time-constant parameter(s) to determine an input signal level for the audio data and/or the AGC gain. In some instances, to determine the AGC gain, the AGC operates in an attack mode or a release mode based on the information.