Conversation Support Device Adaptive Noise Cancellation
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Solution Overview
Problem
Existing conversation support devices struggle to maintain effective active noise cancellation when the sound transfer path between microphones and speakers changes due to environmental variations, leading to reduced noise cancellation performance.
Innovation Solution
A conversation support device that includes a microphone, a speaker, a noise source acquisition unit, a calculator for determining the transfer characteristic of a secondary path, an echo cancellation unit, and an active noise cancellation controller, which generates a noise cancelling signal using the transfer characteristic and noise signal to adaptively control noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active noise cancellation is implemented using fixed transfer characteristics, then initial noise cancellation performance is achieved, but performance degrades when environmental conditions change
Solution Approach 1:
The patent implements dynamic adaptation by continuously estimating secondary path transfer characteristics in real-time based on current environmental conditions. Instead of using fixed pre-measured transfer characteristics, the system dynamically updates the transfer characteristic information to match changing acoustic environments, ensuring reliable noise cancellation performance across varying conditions.
Solution Approach 2:
The system employs feedback mechanisms where the microphone receives both noise and cancellation sound, and this feedback signal is used to continuously re-estimate the secondary path transfer characteristics. This closed-loop feedback enables the system to adapt to environmental changes and maintain optimal noise cancellation performance.
2Adaptability or versatility
If the transfer characteristic is recalculated frequently to follow environmental changes, then adaptability improves, but computational complexity and processing time increase
Solution Approach 1:
The patent performs preliminary measurement of transfer characteristics between the noise cancellation sound speaker and microphone in advance. These pre-measured characteristics serve as a baseline that can be quickly adjusted through subsequent estimation operations, reducing the computational burden during real-time operation while maintaining adaptability.
Solution Approach 2:
The system uses its own operational signals (the cancellation sound generated by its speaker) to automatically re-estimate the secondary path transfer characteristics. This self-service approach eliminates the need for external calibration equipment or complex external measurement procedures, enabling efficient continuous adaptation without significant processing overhead.
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 device achieves stable active noise cancellation even with changes in the environment, improving the listening experience by effectively canceling noise at the talker's location, thereby enhancing two-way conversation support.
Implementation Method 1
a speaker; a microphone; a noise source acquisition unit that acquires a noise signal indicating noise
Data Source
AI summary
A conversation support device includes: a speaker; a microphone; a noise source acquisition unit that acquires a noise signal indicating noise; a first calculator that calculates a transfer characteristic of a secondary path between the speaker and the microphone; an echo cancellation unit that cancels an echo by using the transfer characteristic of the secondary path; a second calculator that calculates a coefficient of an adaptive filter, based on the transfer characteristic of the secondary path and the noise signal; and an active noise cancellation controller that generates a noise cancelling signal by using the coefficient of the adaptive filter and the noise signal. The noise cancelling signal is for controlling cancellation of the noise.