Wireless Headset Voice Pickup Using Adaptive Noise Subtraction
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Solution Overview
Problem
Wireless headsets face challenges in maintaining voice quality in noisy environments due to the dominance of environmental noise over voice signals, as both air microphones and vibration sensors struggle to effectively suppress noise and enhance signal-to-noise ratio (SNR).
Innovation Solution
The method involves combining audio signals from air microphones and vibration sensors, using an adaptive filter to subtract noise from the vibration sensor signal, and adjusting filter settings based on noise levels to optimize the SNR. This includes using a subtractor to reduce noise in high-noise environments and transitioning to a linear combination of signals as noise levels decrease, ensuring clear voice pickup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If air microphones are used to pick up voice in noisy environments, then voice can be detected and captured, but environmental noise dominates the audio signal and voice becomes inaudible
Solution Approach 1:
The patent combines air microphone signals with vibration sensor signals to create a hybrid audio pickup system. The vibration sensor captures bone-conducted voice vibrations while the air microphone captures airborne sound, and the system merges these signals through adaptive filtering to suppress noise and enhance voice intelligibility in noisy environments.
Solution Approach 2:
The vibration sensor acts as an intermediary mechanism that captures voice vibrations through bone conduction, providing an alternative pathway to the voice signal that bypasses the air microphone's vulnerability to environmental noise. This intermediary approach allows the system to access voice information through a different physical medium.
2Object-affected harmful factors
If vibration sensors are used to pick up voice through bone conduction, then voice can be captured with reduced noise sensitivity, but high-frequency content is lost due to low-pass filtering through bone and tissue
Solution Approach 1:
The system merges vibration sensor signals (which provide noise suppression but lose high frequencies) with air microphone signals (which preserve high frequencies but are noisy). The adaptive filter combines these complementary strengths, using the vibration sensor for noise rejection and the air microphone for high-frequency content, thereby resolving the frequency loss problem.
Solution Approach 2:
The adaptive filter dynamically adjusts its parameters based on the acoustic environment to optimize the balance between noise suppression and high-frequency preservation. By changing filter coefficients in response to ambient noise levels and voice characteristics, the system maintains high-frequency fidelity while suppressing environmental noise.
3Measurement precision
If adaptive filtering is applied to suppress noise in vibration sensor signals, then signal-to-noise ratio improves, but system complexity increases
Solution Approach 1:
The adaptive filter operates with feedback from the acoustic environment, continuously adjusting its parameters based on real-time analysis of the audio signal and ambient noise. This feedback mechanism allows the system to automatically optimize noise suppression without requiring complex manual configuration, reducing the practical complexity despite the sophisticated processing involved.
Solution Approach 2:
The adaptive filter serves multiple functions simultaneously: it suppresses environmental noise, enhances voice intelligibility, preserves high-frequency content, and adapts to varying acoustic environments. This multi-functionality consolidates what would otherwise require multiple separate processing stages into a single versatile component, reducing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly improves the signal-to-noise ratio, allowing for clearer voice communication in noisy conditions by effectively suppressing environmental noise and maintaining high voice quality across varying noise levels.
Implementation Method 1
Vibration sensors may pick up the mechanical vibrations in the human skull caused by the vocal cords. Vibrations can be picked up via the skin (Skin Surface Microphones), from the bones (Bone Conduction microphone), or from other tissues in the user's head.
Implementation Method 2
Air microphones pick up airborne acoustic waves and convert them into electrical signals.
Data Source
AI summary
A voice pick-up arrangement (500) provides improved voice performance in a wireless headset (12) exposed to loud environmental noise. A air microphone (220) and a vibration sensor (230) are used for sound pickup. An adaptive filter (450) may be used to subtract the noise from the vibration sensor output in a subtractor (460), thus producing a clear voice signal. A noise level may be monitored and be used for determining whether the adaptive filter is used or for determining the coefficients of the adaptive filter (450). A beam-forming array may be used to suppress a voice component of the picked-up air microphone audio signal.