Active Noise Control Audio Compensation Signal Extraction
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Solution Overview
Problem
Active noise control systems face inaccuracies in generating destructive interference due to the detection of audio sound waves by microphones, which include both desired and undesired sounds, leading to inappropriate sound wave interference.
Innovation Solution
An active noise control system that generates an anti-noise signal to interfere with undesired sounds while also producing sound waves for desired audio, using a microphone to receive sound waves and generate a representative signal combined with an audio compensation signal to remove the audio component from the error signal, allowing for more accurate interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a microphone detects sound waves in the target space to generate an error signal for active noise control, then the system can adjust destructively interfering sound waves, but the microphone also detects desired audio sound waves which are incorrectly included in the error signal leading to inaccurate interference
Solution Approach 1:
The patent extracts the audio signal component from the error signal by generating a separate audio compensation signal that represents the audio portion detected by the microphone. This audio compensation signal is then subtracted from the raw error signal to produce a cleaned error signal that contains only the noise component, eliminating the harmful audio contamination while preserving the useful noise information for active noise control
Solution Approach 2:
The patent introduces an audio compensation signal as an intermediary element that mediates between the raw error signal and the cleaned error signal. This intermediary signal serves as a bridge that allows the system to selectively remove the audio component while maintaining the integrity of the noise component, enabling accurate active noise control without audio interference
2Object-affected harmful factors
If the active noise control system generates sound waves to destructively interfere with detected sounds, then undesired noise can be reduced, but the system also generates incorrect interference patterns that destructively interfere with desired audio signals
Solution Approach 1:
The patent removes the audio component from the error signal by subtracting the audio compensation signal, ensuring that only the noise portion remains. This extracted noise-only error signal is then used to generate anti-noise sound waves, preventing the system from creating destructive interference patterns that would harm the desired audio signals while maintaining effective noise reduction
Solution Approach 2:
The patent implements a feedback mechanism where the cleaned error signal (containing only noise information) is continuously fed back to the active noise control system. This feedback loop allows the system to dynamically adjust the anti-noise generation based on actual noise conditions without being influenced by audio signals, ensuring both effective noise reduction and audio fidelity preservation
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 reduces or eliminates undesired sounds while maintaining the fidelity of desired audio, enhancing the accuracy of destructive interference and audio sound generation.
Implementation Method 1
Active noise control may be used to generate sound waves that destructively interfere with a targeted sound. The destructively interfering sound waves may be produced through a loudspeaker to combine with the targeted sound.
Implementation Method 2
A microphone may receive sound waves present in the target space and generate a representative signal.
Data Source
AI summary
An active noise control system generates an anti-noise signal to drive a speaker to produce sound waves to destructively interfere with an undesired sound in a targeted space. The speaker is also driven to produce sound waves representative of a desired audio signal. Sound waves are detected in the target space and a representative signal is generated. The representative signal is combined with an audio compensation signal to remove a signal component representative of the sound waves based on the desired audio signal and generate an error signal. The active noise control adjusts the anti-noise signal based on the error signal. The active noise control system converts the sample rates of an input signal representative of the undesired sound, the desired audio signal, and the error signal. The active noise control system converts the sample rate of the anti-noise signal.