Multi-beam Sound System Using Adaptive Beamforming for Noise Reduction
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Solution Overview
Problem
In-vehicle sound solutions face challenges with noise interference and echo, particularly when using a single microphone, which affects call quality and speech recognition, and existing adaptive beamformers struggle to effectively receive multiple voices.
Innovation Solution
A multi-beam sound system with a microphone array and an adaptive beamformer that uses a generalized sidelobe canceller and self-tuning recursive least squares algorithm to form multiple beams, reducing noise and echo interference, and includes an echo remover for improved signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single microphone is used for voice signal input, then the device complexity is low, but the signal noise ratio is insufficient and the voice signal is vulnerable to acoustic interference
Solution Approach 1:
The single microphone is segmented into multiple microphones arranged in an array configuration. This segmentation allows the system to process signals from multiple spatial locations, enabling beamforming techniques to enhance the desired voice signal while suppressing noise and interference from other directions, thereby improving the signal noise ratio.
Solution Approach 2:
Multiple microphones are merged into a unified microphone array system that works cooperatively through signal processing algorithms. The combined output of multiple microphones, when processed with beamforming, achieves superior noise rejection and signal enhancement compared to individual microphones, resolving the contradiction between reliability improvement and device complexity.
2Adaptability or versatility
If an adaptive beamformer with one beam is used, then the device complexity is moderate, but it is difficult to receive voices of several persons simultaneously
Solution Approach 1:
The single beam is segmented into multiple independent beams, each capable of targeting different spatial directions. This allows the system to simultaneously form multiple beams pointing toward different speakers, enabling the reception of multiple voices at the same time while maintaining manageable system complexity through modular beam processing.
Solution Approach 2:
The beamforming system is designed with multi-functionality to perform both single-beam and multi-beam operations. The same hardware infrastructure supports multiple operational modes, allowing the system to adaptively switch between receiving a single speaker and receiving multiple speakers simultaneously, thereby enhancing versatility without proportionally increasing device complexity.
3Measurement precision
If beamforming precision is increased to handle decreased steering difference between interference and desired signals, then the signal separation performance improves, but the device complexity and computational requirements increase
Solution Approach 1:
The beamforming system employs dynamic adaptation through adaptive algorithms that automatically adjust beam parameters in real-time based on the acoustic environment. This dynamic capability allows the system to maintain high precision signal separation without requiring overly complex fixed-structure designs, as the system adapts its complexity only when and where needed.
Solution Approach 2:
The system incorporates feedback mechanisms where the output of the beamformer is continuously monitored and fed back to adjust the beamforming weights and parameters. This feedback loop enables the system to self-optimize its precision, achieving high measurement precision through iterative refinement rather than through inherently complex hardware designs.
Data Source
AI summary
A multi-beam sound system includes a fixed beamforming section which steers the input signal inputted from the microphone array to an intended direction, a blocking matrix which receives the input signal and acquires a noise reference signal from the input signal, a variable beamforming section which acquires an adaptive noise signal from the noise reference signal outputted from the blocking matrix, and a generalized sidelobe canceller (GSC) which includes canceling means for outputting an object signal from the input signal outputted from the fixed beamforming section by removing the adaptive noise signal from the input signal. The fixed beamforming section steers the input signal in at least two directions.