Dynamic Silent Zone Generation for Head-Moving Users
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Solution Overview
Problem
Active noise cancellation systems in vehicles often fail to maintain effective noise reduction when the user moves their head, as the silent zones generated are typically small and tailored for standard anatomy, leading to unsatisfactory noise cancellation for users with non-standard ear positions.
Innovation Solution
The system employs a multi-channel feedforward active noise reduction system with microphones and loudspeakers arranged in a headrest and additional microphones positioned above the user, using adaptive filters and LMS algorithms to create larger silent zones that follow the user's head movement, ensuring noise cancellation across a broader frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed ANC position is used with standard loudspeaker and microphone arrangement, then noise cancellation is effective at that specific position, but the silent zone becomes small and users experience unsatisfactory noise cancellation when moving their heads or having non-standard anatomy
Solution Approach 1:
The patent implements dynamic silent zone generation by continuously tracking the user's ear positions and adjusting the ANC parameters in real-time. Multiple microphones detect ear positions, and the system adapts the loudspeaker output accordingly, transforming the static ANC system into a dynamic one that follows head movements and accommodates different anatomies.
Solution Approach 2:
The system uses multiple microphones serving dual functions: error microphones for noise detection and position microphones for ear location tracking. This multi-functional approach allows the same hardware to support both noise cancellation and adaptive positioning, making the system universally applicable to various head positions and anatomies.
2Measurement precision
If separate silent zones are generated for each ear at fixed positions, then noise cancellation works for standard anatomy users in preferential position, but users with non-standard anatomy or head movements experience degraded performance
Solution Approach 1:
The system dynamically adjusts the silent zone positions and characteristics based on real-time ear position detection. Instead of fixed silent zones, the ANC parameters are continuously adapted to maintain effective noise cancellation regardless of head position or anatomy, improving user comfort and ease of operation.
Solution Approach 2:
The system uses feedback from position microphones to continuously monitor ear locations and adjust the ANC control signals accordingly. This closed-loop feedback mechanism ensures that the silent zones remain aligned with the user's ears, maintaining noise cancellation performance across different operating conditions.
3Manufacturing precision
If the silent zone is tailored for standard user anatomy looking straight ahead, then noise cancellation is optimized for that specific configuration, but users with out-of-the-norm anatomy experience less satisfactory results as their ears may not be fully located in the silent zones
Solution Approach 1:
The system transitions from static silent zone positioning optimized for standard anatomy to dynamic positioning that adapts to each user's actual ear locations. The continuous adjustment of ANC parameters based on real-time position detection enables the system to accommodate varied anatomy while maintaining high positioning accuracy.
Solution Approach 2:
The system changes the operational parameters of the ANC system based on detected ear positions. By adjusting the frequency range, gain, and phase of the anti-noise signals according to the user's anatomy and head position, the system maintains effective noise cancellation across diverse user populations.
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
This configuration significantly enlarges the silent zones and improves noise cancellation performance across a wider frequency range, providing a more consistent and satisfactory experience for users regardless of head position, even for those with non-standard anatomy.
Implementation Method 1
Active noise cancellation systems generally reduce the sound pressure level in a defined silent zone at least for a certain frequency range
Data Source
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AI summary
A system for generating silent zones at a listening position comprises a first loudspeaker disposed at a first position adjacent to the listening position and configured to radiate sound that corresponds to a sound signal, a first error microphone disposed at the first position and configured to pick up noise radiated by a noise source via a primary path to the listening position, and configured to generate a corresponding first microphone signal, a second loudspeaker disposed at a second position adjacent to the listening position and configured to radiate sound that corresponds to a sound signal, a second error microphone disposed at the second position and configured to pick up noise radiated by a noise source via a primary path to the listening position and configured to generate a corresponding second microphone signal, a third microphone disposed at a third position adjacent to the listening position and configured to pick up noise radiated by a noise source via a primary path to the listening position and configured to generate corresponding third microphone signals, and an ANC controller configured to receive the microphone signals from the third microphone and at least one of the first and second microphone, and to provide a loudspeaker input signal to at least one of the loudspeakers based on the third microphone signal and one of the first and the second microphone signal. A distance between the third position and the first position equals a distance between the third position and the second position such that the first, second and third microphones form the corners of an isosceles triangle.