Voice Isolation System Using Asymmetric Microphone Coupling
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Solution Overview
Problem
Existing communication headsets with active noise cancellation capabilities do not effectively reduce ambient noise for far-end listeners during voice calls, as the noise cancellation benefits are not transmitted to them.
Innovation Solution
A voice isolation system in a communication headset that exploits the asymmetry in speech coupling between feedback and feedforward microphones to enhance the user's speech signal, generating covariance signals and applying filters to improve signal-to-noise ratio, while using sensors for off-ear detection and beamforming techniques to adapt to changing noise conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active noise cancellation is implemented in headsets, then the perceived noise level for the user is reduced, but the noise level for far-end listeners is not reduced
Solution Approach 1:
The system separates noise processing into two distinct paths: local noise cancellation for the user's ear and remote noise suppression for the transmitted audio signal. The headset processes ambient noise independently for local playback while simultaneously processing the user's voice signal for transmission, allowing each path to be optimized separately.
Solution Approach 2:
The system introduces an intermediary processing stage that analyzes the relationship between ambient noise captured by microphones and the user's voice signal. This intermediary processor generates noise compensation signals that are applied to the transmitted audio stream, effectively mediating between the local noise cancellation function and the remote transmission quality.
2Measurement precision
If multiple microphones are used for voice capture, then speech signal quality improves, but device complexity increases
Solution Approach 1:
The system exploits the asymmetric coupling characteristics of different microphones: the feedback microphone is partially coupled to user speech through bone conduction while the feedforward microphone is predominantly acoustically coupled. This asymmetry is leveraged to distinguish between speech and ambient noise signals, improving speech isolation without requiring complex additional hardware.
Solution Approach 2:
The system uses feedback from the microphones to continuously monitor and adapt the noise cancellation processing. The feedback microphone captures both ambient noise and bone-conducted speech, which is used to generate adaptive noise compensation signals that are applied in real-time to the transmitted audio stream.
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 system effectively isolates the user's voice signal, improving speech clarity for both the user and far-end listeners by enhancing the signal-to-noise ratio and adapting to ambient noise, thereby providing better noise cancellation for all parties involved in the call.
Implementation Method 1
one of the microphones (e.g., the feedback microphone in a noise-canceling system) being partially coupled to the user's speech through bone conduction
Implementation Method 2
an acoustic echo-cancelation subsystem to receive a plurality of input signals, subtract an interference component from the input signals, and provide a plurality of output signals
Implementation Method 3
an adaptive beamformer subsystem to receive the plurality of output signals from the acoustic echo-cancelation subsystem and compute a signal-to-noise ratio (SNR) enhanced signal based on the received output signals
Implementation Method 4
a residual noise suppressor subsystem to attenuate at least one portion of the SNR enhanced signal received from the adaptive beamformer subsystem based on the at least one portion having an SNR below a predetermined SNR threshold
Data Source
AI summary
The disclosure includes a voice isolation system comprising an acoustic echo-cancelation subsystem configured to receive a plurality of input signals, subtract an interference component from the input signals, and provide a plurality of output signals. The system also includes an adaptive beamformer subsystem configured to receive the plurality of output signals from the acoustic echo-cancelation subsystem and compute a signal-to-noise ratio enhanced signal based on the received output signals. The system also includes a residual noise suppressor subsystem configured to attenuate at least one portion of the SNR enhanced signal received from the adaptive beamformer subsystem based on the at least one portion having an SNR below a predetermined SNR threshold. The system also includes an automatic gain control subsystem configured to process a signal outputted from the residual noise suppressor subsystem and transmit a resulting signal as an output signal.