Active Noise Reduction Using Synchronization Signals
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Solution Overview
Problem
Existing active noise cancellation systems are ineffective in creating a quiet zone at a distance from the noise source, especially in environments with non-stationary noise sources like music or vocal signals, as they struggle to accurately generate and broadcast antiphase signals that account for distortion and environmental changes, leading to incomplete noise reduction and interference with ambient audio signals.
Innovation Solution
A system that uses synchronization signals to dynamically calculate and generate antiphase acoustic signals, synchronized with the predefined noise, allowing for real-time adaptation to environmental distortions and precise timing, enabling effective noise reduction in quiet zones while maintaining ambient audio signals by using a unique synchronization signal that combines with the noise and is transmitted electrically and acoustically, ensuring destructive interference of the undesired noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing active noise cancellation systems are used to create a quiet zone at a distance from the noise source, then noise reduction is attempted, but the system fails to accurately generate and broadcast antiphase signals that account for distortion and environmental changes
Solution Approach 1:
The system employs feedback by continuously monitoring the actual noise environment and adjusting the antiphase signal generation accordingly. The synchronization signal provides a reference that enables the system to detect environmental changes and distortion, then feed this information back to modify the cancellation signal in real-time, improving both measurement precision and reliability.
Solution Approach 2:
The system changes parameters by dynamically adjusting the antiphase signal characteristics based on environmental conditions. The synchronization signal enables detection of parameter changes in the acoustic environment (such as temperature, humidity, physical obstructions), and the system modifies its output parameters (frequency, amplitude, phase) to maintain effective noise cancellation despite these changes.
2Object-affected harmful factors
If antiphase signals are generated to reduce predefined noise, then noise attenuation is achieved in quiet zones, but ambient audio signals are interfered with and reduced
Solution Approach 1:
The system applies local quality by creating a localized quiet zone with specific acoustic properties rather than uniformly canceling all sounds. The synchronization signal enables precise spatial targeting, allowing the antiphase signals to be generated only in the desired quiet zone while preserving ambient audio signals in other areas. This selective approach attenuates harmful noise locally without causing widespread loss of ambient audio information.
Solution Approach 2:
The system segments the acoustic environment by distinguishing between predefined noise signals (to be canceled) and ambient audio signals (to be preserved). The synchronization signal provides a reference that helps segment and identify the target noise sources, enabling the system to generate antiphase signals specifically for those sources while leaving other ambient sounds unaffected.
3Adaptability or versatility
If synchronization signals are used to dynamically calculate antiphase signals, then real-time adaptation to environmental distortions is achieved, but device complexity increases
Solution Approach 1:
The system introduces an intermediary element - the synchronization signal - that mediates between the noise source and the antiphase signal generation. This synchronization signal acts as a reference that simplifies the complex task of real-time adaptation by providing a known reference pattern against which environmental distortions can be measured and compensated, reducing the overall system complexity while maintaining high adaptability.
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 significant attenuation of predefined audio acoustic noise in quiet zones, even at distances from the noise source, while allowing for conversation and the preservation of ambient audio signals, improving noise reduction in the high-frequency spectrum and adapting to dynamic environments, thus enhancing user experience and reducing noise interference.
Implementation Method 1
The system achieves significant attenuation of predefined audio acoustic noise in quiet zones... allowing for conversation and the preservation of ambient audio signals... ensuring destructive interference of the undesired noise
Data Source
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AI summary
The present invention is a method and system for active reduction of a predefined audio acoustic signal (AAAS), also referred to as "noise", in a quiet zone, without interfering undefined acoustic noise signals within as well as outside the quiet zone, by generating accurate antiphase AAAS signal. The accuracy of the generated antiphase AAAS is obtained by employing a unique synchronization signal(s) (SYNC) which is generated and combined with the predefined AAAS. The combined signal is electrically transmitted (referred to as the "electric channel") to a processing "quieting component". Simultaneously, the generated SYNC signal is acoustically broadcasted near the predefined AAAS and merges with it. A microphone in the quiet zone receives the merged acoustic signals that arrive via the air (referred to as the "acoustical channel") to the quiet zone and a receiver in the quieting component receives the combined electrical AAAS and SYNC signal that arrive wire or wireless to the quiet zone. In the quiet component the SYNC is detected from both electrical and acoustical channels, the detected SYNC signals with the electrically received AAAS signal are used to calculate the timing and momentary amplitude for generating an accurate acoustic antiphase AAAS signal to cancel the acoustic predefined AAAS. By continuously and periodically updating the SYNC signal enables to dynamically evaluate acoustical environmental distortions that might appear due to echo, reverberations, frequency non-linear response, or due to other distortions mechanisms.