Vehicle Noise Reduction via Virtual Microphone Averaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing noise reduction systems in vehicles face challenges in maintaining stable noise reduction performance under varying operating conditions, particularly due to head movements affecting the quiet zone's stability.
Innovation Solution
A noise reduction system comprising a controller, a reference sensor, a sound generator, and a monitor-microphone array, which implements a virtual sensing algorithm to estimate an error signal at a virtual microphone position. The system includes an averaging unit to calculate an average error signal, taking into account a direct residual signal from a direct monitor microphone, and a dynamic adjustment unit to update anti-noise parameters based on this average error signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a virtual microphone is used to estimate the error signal at a specific position, then noise reduction effectiveness at that position is improved, but stability under head movements deteriorates
Solution Approach 1:
The error signal estimation is segmented into multiple virtual microphone positions rather than relying on a single position. This allows the system to maintain noise reduction effectiveness across different spatial locations and head movements by combining information from multiple segments of the noise reduction area.
Solution Approach 2:
Multiple error signals from different virtual microphone positions are merged into a single average error signal. This combination approach integrates information from various locations, providing both the precision needed for effective noise cancellation and the stability required to handle head movements.
2Adaptability or versatility
If multiple virtual microphones are used to cover different positions, then adaptability to head movements is improved, but computational complexity increases
Solution Approach 1:
Instead of using an excessive number of virtual microphones to cover all possible head positions, the system uses a limited set of strategically positioned virtual microphones. This partial action approach provides sufficient adaptability while keeping computational complexity manageable.
Solution Approach 2:
The multiple virtual microphones serve multiple functions simultaneously: they provide error signal estimation for different positions, enable adaptation to head movements, and through averaging, contribute to overall system stability. This multi-functionality maximizes adaptability without proportionally increasing complexity.
3Measurement precision
If the noise reduction area is limited to a small spatial region, then noise cancellation precision is improved, but ease of operation deteriorates due to sensitivity to head movements
Solution Approach 1:
The system transitions from a single-point noise reduction approach to a multi-dimensional approach by distributing multiple virtual microphones throughout the noise reduction area. This spatial distribution allows the system to maintain precision while reducing sensitivity to head movements by providing coverage across multiple dimensions of the passenger area.
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 significantly higher stability and robustness of the noise reduction algorithm, ensuring effective noise cancellation even under dynamic conditions such as head movements, by using the direct monitor microphone signal as a 'golden reference'.
Implementation Method 1
The anti-noise is superimposed on the undesired background noise in that the background noise is reduced or almost completely eliminated in a quiet zone by means of destructive interference
Data Source
AI summary
A noise reduction system for actively compensating background noise generated by a noise source in a noise reduction area in a passenger transport area of a vehicle. The system includes a microphone array having a reference microphone. An averaging unit is configured to calculate an average error signal, which is calculated based on at least the error signal of a virtual microphone and a direct residual signal of a directed monitor microphone.