Wearable Log-Spiral Microphone Array for Directional Audio
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Solution Overview
Problem
Existing directional microphone arrays for hearing aids are ineffective in noisy environments due to wide beam widths, large side lobes, inconsistent performance across frequencies, and discomfort, allowing too much ambient and directional noise.
Innovation Solution
A wearable directional microphone array using a log-spiral configuration of microphones on a flexible printed circuit board integrated with an electronics module, providing beamforming and noise reduction, with a narrow beam width and high directivity, mounted discreetly on a garment like a vest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a directional microphone array is designed with narrow beam width for high directionality, then the ability to filter ambient and directional noise is improved, but the device complexity and mounting comfort deteriorate
Solution Approach 1:
The microphone array is segmented into multiple individual microphones arranged in a log-spiral pattern, where each microphone captures sound independently and the signals are processed separately to achieve beamforming. This segmentation allows for precise control of beam width and directionality while distributing the complexity across multiple simple sensor elements rather than a single complex structure.
Solution Approach 2:
The patent transitions from traditional linear or planar microphone array configurations to a three-dimensional log-spiral arrangement. This dimensional change enables the array to achieve narrow beam width and high directionality in multiple spatial dimensions simultaneously, improving noise filtering effectiveness while maintaining a compact wearable form factor.
2Reliability
If the beam width is reduced to less than or equal to 25 degrees for high directionality, then the capture of desired sound sources is improved, but the performance consistency across frequencies deteriorates
Solution Approach 1:
The patent employs parameter changes by adjusting the spacing, orientation, and phase relationships between individual microphones in the log-spiral array to achieve frequency-independent beamforming. By carefully designing the geometric parameters of the spiral configuration and the signal processing parameters, the system maintains consistent beam width and directionality across a wide frequency range, resolving the contradiction between narrow beam width and frequency consistency.
3Reliability
If the number of microphones is increased to improve directivity gain, then the noise filtering capability is improved, but the device size and comfort deteriorate
Solution Approach 1:
The patent achieves high directivity gain with a compact device size by arranging microphones in a three-dimensional log-spiral configuration rather than a planar arrangement. This spatial distribution of microphones in multiple dimensions allows the array to achieve the equivalent directivity gain of a much larger planar array while fitting within a small wearable volume, thus maintaining comfort.
Solution Approach 2:
The log-spiral arrangement naturally nests the microphones in a compact, space-efficient configuration where the spiral pattern allows tight packing while maintaining the necessary separation for directional processing. This nesting approach maximizes the use of available space to achieve high directivity gain without increasing the overall device volume.
4Adaptability or versatility
If movable plates and grills are used to change acoustic resistance, then the directional effect can be adjusted, but the device complexity and discomfort deteriorate
Solution Approach 1:
The patent replaces mechanical adjustment mechanisms (movable plates and grills) with an electronic signal processing system. The directional properties are controlled by dynamically adjusting the phase and amplitude weights of signals from individual microphones through digital signal processing, eliminating the need for complex mechanical structures while maintaining full adaptability in directional property adjustment.
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 solution effectively filters ambient and directional noise, providing clear, natural-sounding audio with high gain and consistent performance across frequencies, even in noisy environments, while being comfortable and cost-effective.
Implementation Method 1
an array of sensors, such as, but not limited to, microphones, acoustic sensors, acoustic renderers, and transducers
Implementation Method 2
spatially filtering received sound so that sounds arriving from the look direction are accepted (constructively combined) and sounds arriving from other directions are rejected (destructively combined)
Data Source
AI summary
A wearable microphone array apparatus and system used as a directional audio system and as an assisted listening device. The present invention advances hearing aids and assisted listening devices to allow construction of a highly directional audio array that is wearable, natural sounding, and convenient to direct, as well as to provide directional cues to users who have partial or total loss of hearing in one or both ears. The advantages of the invention include simultaneously providing high gain, high directivity, high side lobe attenuation, and consistent beam width; providing significant beam forming at lower frequencies where substantial noises are present, particularly in noisy, reverberant environments; and allowing construction of a cost effective body-worn or body-carried directional audio device.