Microphone Array Directional Audio Capture Using LPC and TDOA
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Solution Overview
Problem
Existing audio capturing systems face challenges in enhancing signal quality and reducing computational complexity, especially under noisy conditions, and struggle to accurately filter out undesired sources in multi-microphone setups.
Innovation Solution
The method involves using at least two microphones with automatic gain control (AGC) to adjust audio data, calculating linear predictive coding (LPC) residues, determining source directions via time difference of arrival (TDOA), and attenuating sources outside a predefined spatial direction using a processing circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If beamforming and TDOA techniques are used to enhance audio capturing, then speech recognition accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by performing AGC (Automatic Gain Control) on the audio signals before calculating LPC residues and performing TDOA analysis. This preprocessing step ensures that the signals are at appropriate amplitude levels beforehand, which simplifies subsequent processing steps and reduces computational complexity while maintaining speech recognition accuracy.
Solution Approach 2:
The patent extracts only the essential components needed for accurate speech recognition by calculating LPC residues to isolate the excitation source information. This extraction process removes unnecessary signal components and focuses computation on the most relevant features, thereby reducing computational complexity while preserving measurement precision.
2Adaptability or versatility
If multiple microphones are used to capture audio from different directions, then ability to filter undesired sources is improved, but device complexity increases
Solution Approach 1:
The patent segments the audio processing task by assigning specific functions to different components: multiple microphones capture signals, AGC adjusts gain levels, LPC residue calculation extracts source characteristics, and TDOA determines direction. This segmentation allows the system to handle complex multi-directional filtering through coordinated simple operations, reducing overall device complexity while improving adaptability.
Solution Approach 2:
The patent introduces intermediate processing steps (AGC and LPC residue calculation) that mediate between the raw microphone signals and the final TDOA-based direction determination. These intermediaries simplify the relationship between multiple microphones and the filtering function, making the system more adaptable without proportionally increasing complexity.
3Measurement precision
If LPC residue calculation is performed to improve TDOA accuracy, then source direction determination is improved, but processing time increases
Solution Approach 1:
The patent performs AGC as a preliminary action before LPC residue calculation, ensuring that the input signals are already optimized for the residue computation. This preliminary preparation reduces the iterative adjustments needed during LPC analysis, thereby reducing processing time while maintaining the accuracy benefits of LPC-based TDOA.
4Reliability
If automatic gain control is applied to adjust audio data, then signal quality is improved, but computational complexity increases
Solution Approach 1:
The patent implements AGC as a self-service mechanism where the system automatically monitors and adjusts its own signal levels without external intervention. This self-regulating approach improves signal quality and reliability while minimizing the need for complex external control systems, thereby reducing overall computational complexity.
Data Source
AI summary
Accordingly, the present disclosure is directed to an audio capturing enhancement method and an audio capturing system using the same method. The audio capturing system includes at least but not limited to two microphones for recording an audio data, an amplifier coupled to the at least two microphones for adjusting the audio data by applying automatic gain control (AGC) in order to generate a gain adjusted data that is within a predefined level, and a processing circuit coupled to the amplifier for calculating a linear predictive coding (LPC) residue of the gain adjusted data, determining from the LPC residue a first source at a first direction relative to the at least two microphones based on time different of arrival (TDOA), and attenuating any source at a second direction that is outside of a predefined direction.