Noise Cancellation via Predictive Remote Error Estimation
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Solution Overview
Problem
Existing noise-cancellation systems struggle to effectively cancel noise at locations remote from the reference sensor, as the error signal generated by the reference sensor is not directly indicative of the noise at the remote location, leading to suboptimal noise cancellation.
Innovation Solution
A noise-cancellation system that includes a noise-cancellation filter, an actuator, a reference sensor, and an adjustment module, which estimates or predicts the error signal at a remote location using filters that estimate the relationships between the reference sensor, the actuator, and the remote location, allowing for adjustments to the noise-cancellation signal to optimally cancel noise at the remote location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference sensor is used to generate error signal for noise cancellation, then noise cancellation can be implemented, but the error signal is not directly indicative of noise at remote locations leading to suboptimal cancellation performance
Solution Approach 1:
The patent introduces predictive filters as intermediary components that mediate between the reference sensor signal and the remote location noise estimation. These filters act as mathematical models that predict the relationship between the reference sensor and remote locations, allowing the system to estimate noise at remote locations without direct measurement. This resolves the contradiction by creating an informational bridge that preserves remote location noise information despite using a reference sensor at a different location.
Solution Approach 2:
The patent creates a virtual copy of the remote location noise signal through predictive filtering. Instead of directly measuring the noise at the remote location, the system generates a predicted copy of what the noise signal would be at that location based on the reference sensor input and the predicted transfer function. This copied signal is then used for adaptive filtering to achieve noise cancellation at the remote location, effectively resolving the information loss problem.
2Reliability
If traditional noise cancellation systems are used with reference sensor, then system complexity is limited, but noise cancellation effectiveness at remote locations is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing predicted transfer functions that represent the relationship between the reference sensor and remote locations. These transfer functions are computed in advance and stored for later use during adaptive filtering operations. This preliminary computation enables the system to quickly adapt to different remote locations without performing complex real-time calculations, thereby improving noise cancellation effectiveness while managing system complexity.
Solution Approach 2:
The patent changes the parameter representation from direct noise measurement to predicted noise estimation using transfer functions. By transforming the problem from measuring actual noise at remote locations to predicting noise based on reference sensor signals and pre-computed transfer functions, the system achieves better noise cancellation effectiveness. The parameter change involves using predicted error signals instead of actual error signals, which resolves the contradiction between effectiveness and 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 system achieves effective noise cancellation at remote locations by predicting the error signal, thereby minimizing residual noise and improving the overall noise cancellation performance beyond what is possible with traditional systems.
Implementation Method 1
an actuator disposed at a first location within a predefined volume and configured to receive the noise-cancellation signal and to transduce a noise-cancellation audio signal within the predefined volume
Implementation Method 2
adjusting the noise-cancellation filter, based on the filter output signal, such that the noise-cancellation audio signal destructively interferes with the undesired noise at the third location
Data Source
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AI summary
A noise-cancellation system includes a noise-cancellation filter configured to generate a noise-cancellation signal based on a noise signal received from a noise sensor; an actuator disposed at a first location within a predefined volume and configured to receive the noise-cancellation signal and to transduce a noise-cancellation audio signal within the predefined volume; a reference sensor disposed at a second location within the predefined volume and to output a reference sensor signal, the reference sensor signal being representative of an undesired noise at the second location; a filter configured to filter the noise-cancellation signal and the reference sensor signal to output a filter output signal, the filter output signal representing an estimate of the undesired nose at a third location remote from the first location and the second location; and an adjustment module configured to adjust the noise-cancellation filter, based on the filter output signal, such that the noise-cancellation audio signal destructively interferes with the undesired noise at the third location.