Microphone Gain Selection for Speech Detection Without Saturation
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Solution Overview
Problem
Existing audio processing systems face challenges in dynamically adjusting the gain of audio signals from microphones, leading to signal saturation at high levels and reduced detectability at low levels, due to varying user proximity and environmental conditions.
Innovation Solution
A system with multiple gain adjusters and a gain controller that determines the appropriate gain based on external criteria such as user proximity and signal metrics, selecting between lower and higher gains to optimize audio processing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high gain is applied to the audio signal, then speech detectability is improved when the user is far away or speaking softly, but signal saturation occurs when the input signal level is high
Solution Approach 1:
The system dynamically switches between a first gain adjuster (lower gain) and a second gain adjuster (higher gain) based on real-time signal level detection. When the audio signal level exceeds a threshold, the system selects the first gain adjuster to prevent saturation; when the signal level is below the threshold, it selects the second gain adjuster to improve speech detectability. This dynamic adaptation resolves the contradiction by making the gain selection conditional on the current signal state.
Solution Approach 2:
The system changes the gain parameter based on the detected signal level. By monitoring whether the audio signal level exceeds a predetermined threshold, the system adjusts the gain parameter between two discrete values (first gain and second gain). This parameter change strategy allows the system to optimize speech detectability while avoiding signal saturation under different operating conditions.
2Object-affected harmful factors
If a low gain is applied to the audio signal, then signal saturation is prevented when the input signal level is high, but speech detectability deteriorates when the user is far away or speaking softly
Solution Approach 1:
The system employs dynamic gain selection by switching between a first gain adjuster (lower gain) and a second gain adjuster (higher gain) based on real-time signal level assessment. When the audio signal level is high (exceeding the threshold), the first gain adjuster is selected to prevent saturation; when the signal level is low (below the threshold), the second gain adjuster is selected to enhance speech detectability. This dynamic approach resolves the contradiction by adapting gain to current signal conditions.
Solution Approach 2:
The system adjusts the gain parameter between two discrete values based on the detected signal level relative to a threshold. This parameter change enables the system to prevent signal saturation under high input conditions while maintaining good speech detectability under low input conditions, effectively resolving the contradiction between these two opposing requirements.
3Device complexity
If a fixed gain is applied to the audio signal, then the system complexity is reduced, but the audio processing performance deteriorates under varying signal levels
Solution Approach 1:
The system segments the gain adjustment function into two separate gain adjusters: a first gain adjuster for high signal levels and a second gain adjuster for low signal levels. Each gain adjuster is optimized for its specific operating range. A gain selector then chooses the appropriate gain adjuster based on the current signal level. This segmentation allows the system to maintain good audio processing performance across varying signal levels while keeping the overall structure relatively simple.
Solution Approach 2:
The system uses two different gain parameters (first gain and second gain) that are selected based on the detected signal level. This parameter change strategy allows the system to optimize audio processing performance for both high and low signal conditions without requiring a complex continuous gain control mechanism, thus balancing performance and complexity.
Data Source
AI summary
A device including one or more processors configured to, based on at least one of an external criterion or a signal-based criterion, output a first gain adjusted signal from a first gain adjuster or a second gain adjusted signal from a second gain adjuster as an input to an audio processing operation. The first gain adjusted signal corresponds to a first gain applied to an audio signal from a microphone and the second gain adjusted signal corresponding to a second gain applied to an audio signal from a microphone. The signal-based criterion is based on whether a first signal metric associated with the first gain adjusted signal or a second signal metric associated with the second gain adjusted signal is closer to a target metric.