Steerable Beam Microphone Array for Multi-Directional Noise Reduction
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Solution Overview
Problem
Existing headphones with active noise control (ANC) struggle to effectively reduce noise from multiple noise sources coming from various directions.
Innovation Solution
The proposed solution involves an active noise reducing earphone with a rigid cup shell, a microphone arrangement with steerable beam directivity characteristics, and an active noise control filter. The microphone arrangement includes an array of multiple microphones distributed over the outer surface of the shell, and a beamformer block that provides a directivity characteristic with at least one steerable beam. This setup allows for an awareness mode of operation where beams are steered in different directions to evaluate signal-to-noise ratios, selecting the direction of the desired-sound source and deactivating the active noise control filter in that mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional ANC microphones are used to reduce noise from multiple directions, then noise reduction capability is improved, but the system cannot effectively handle noise sources from various directions
Solution Approach 1:
The patent divides the single microphone function into multiple microphones arranged in an array on the earphone shell. Each microphone captures sound from different spatial positions, enabling the system to segment and process noise from multiple directions simultaneously. This segmentation allows the beamformer to independently analyze and reduce noise from various sources without compromising overall noise reduction capability.
Solution Approach 2:
The patent introduces spatial dimensionality by distributing microphones across the three-dimensional surface of the earphone shell rather than using a single point microphone. This spatial arrangement creates multiple acoustic measurement points that enable directional noise identification and reduction. The beamformer utilizes these spatial dimensions to form steerable beams that can target noise sources from any direction, effectively adding a spatial dimension to the noise reduction process.
2Measurement precision
If a microphone array with beamforming is implemented, then directional sound reception is improved, but device complexity increases
Solution Approach 1:
The patent designs the microphone array and beamforming system to perform multiple functions: noise reduction, awareness mode operation, and directional sound reception. The same microphone array that provides directional capabilities also enables the system to identify and reduce noise from specific directions. This multi-functionality reduces the need for separate components, thereby managing complexity while maintaining measurement precision.
Solution Approach 2:
The beamforming system automatically adapts to the acoustic environment by continuously analyzing sound signals and adjusting beam directions without user intervention. The system self-regulates by identifying noise sources and desired sound directions, switching between noise reduction and awareness modes as needed. This self-service capability reduces the need for complex manual controls and external adjustments, managing system complexity through autonomous operation.
3Object-affected harmful factors
If active noise control filter is always active, then noise reduction is maximized, but awareness of desired sound sources is reduced
Solution Approach 1:
The patent implements dynamic switching between noise reduction mode and awareness mode based on real-time acoustic environment analysis. The system continuously monitors sound signals and automatically adjusts the active noise control filter status. When a desired sound source is detected, the system switches to awareness mode to preserve sound information; when noise dominates, it activates noise reduction. This dynamic adaptation resolves the contradiction by making noise reduction effectiveness and sound awareness complementary rather than conflicting.
Solution Approach 2:
The system uses feedback from the microphone array to continuously monitor the acoustic environment and adjust noise control operations accordingly. The beamformer analyzes incoming signals to identify whether the primary content is noise or desired sound, and this feedback controls the activation state of the active noise control filter. This feedback mechanism ensures that noise reduction is applied only when beneficial, preserving awareness of desired sound sources while maximizing noise reduction effectiveness.
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 solution enhances the noise reduction capabilities of headphones by effectively reducing noise from multiple directions and allowing for an awareness mode that optimizes sound reception from desired sources.
Implementation Method 1
a microphone arrangement configured to pick up sound with at least one steerable beam directivity characteristic
Implementation Method 2
an active noise control filter configured to provide, based on the first electrical signal, a second electrical signal
Implementation Method 3
The noise is collected by the microphone, is inverted in phase and is emitted from the speaker to reduce the external noise
Implementation Method 4
a speaker disposed in the opening of the cavity and configured to generate sound from the second electrical signal
Implementation Method 5
a beamformer block electrically connected to the array of multiple microphones and configured to provide in connection with the array of multiple microphones, a directivity characteristic of the array of multiple microphones that includes at least one beam
Data Source
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AI summary
An active noise reducing earphone includes a rigid cup shell having an inner surface and an outer surface, the inner surface encompassing a cavity with an opening, a microphone arrangement configured to pick up sound with at least one steerable beam directivity characteristic, and to provide a first electrical signal that represents the picked-up sound, an active noise control filter configured to provide, based on the first electrical signal, a second electrical signal, and a speaker disposed in the opening of the cavity and configured to generate sound from the second electrical signal. The active noise control filter has a transfer characteristic that is configured so that noise that travels through the shell from beyond the outer surface to beyond the inner surface is reduced by the sound generated by the speaker. The microphone arrangement includes an array of multiple microphones, the multiple microphones being distributed over the outer surface of the shell, and a beamformer block electrically connected to the array of multiple microphones and configured to provide in connection with the array of multiple microphones, a directivity characteristic of the array of multiple microphones that includes at least one beam. The microphone arrangement is configured to provide an awareness mode of operation in which one or more beams are steered in different directions and to evaluate a signal-to-noise ratio of each beam, the direction in which one beam thereof having a highest signal-to-noise ratio is selected as the direction of a desired-sound source, and the active noise control filter is either activated or deactivated in the awareness mode while the one beam with the highest signal-to-noise ratio is selected as the direction of the desired-sound source.