PCB-Mounted Tetrahedral Microphone Array for Compact Directional Audio
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Solution Overview
Problem
Conventional tetrahedral ambisonic surround sound microphones, or 'tetramics,' are not suitable for consumer applications due to manufacturing complexities, high costs, and large volume, limiting their use to high-fidelity professional audio recording and not being embeddable in compact devices like mobile phones or hearing aids.
Innovation Solution
A directional sound reception system using an array of pressure sensors with support means having two opposite surfaces and four sensors, where at least one sensor is supported on each surface, allowing for compact and cost-effective design suitable for consumer devices, with processing means to generate directional pressure gradients and separate acoustic signals from multiple sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tetrahedral ambisonic surround sound microphones (tetramics) are used, then high-fidelity ambisonic audio recording is achieved, but the device becomes complex to manufacture, expensive, and large in volume
Solution Approach 1:
The patent replaces the conventional mechanical tetrahedral structure with customised mechanical assemblages and fixings with a printed circuit board (PCB) mounting system. The microphones are mounted on a PCB using standard electronic manufacturing techniques, eliminating the need for complex mechanical assemblies while maintaining the tetrahedral geometric arrangement for accurate acoustic measurement.
Solution Approach 2:
The patent changes the physical parameters of the microphone arrangement by mounting microphones on opposite sides of a PCB with their diaphragms facing each other across the board thickness. This parameter change (from outward-facing to inward-facing diaphragms, and from external mechanical mounting to internal PCB integration) reduces the overall device volume while preserving the tetrahedral geometry's acoustic properties.
2Measurement precision
If conventional tetrahedral ambisonic surround sound microphones (tetramics) are used, then high-fidelity ambisonic audio recording is achieved, but the manufacturing cost increases due to manual assembly requirements
Solution Approach 1:
The patent substitutes manual mechanical assembly with automated PCB manufacturing processes. The microphones are mounted on the PCB using standard reflow soldering or other automated electronic component attachment techniques, enabling high-volume production with consistent precision and significantly reduced labor costs compared to custom mechanical assemblages.
3Measurement precision
If conventional tetrahedral ambisonic surround sound microphones (tetramics) are used, then high-fidelity ambisonic audio recording is achieved, but the device volume becomes large compared to the component microphones
Solution Approach 1:
The patent utilizes the third dimension (PCB thickness) to accommodate the microphone diaphragms facing each other, rather than arranging them in a planar configuration. This vertical stacking approach allows the tetrahedral array to be compact in the horizontal plane while maintaining the required spatial separation between microphones through the PCB thickness, thereby reducing overall device volume.
Solution Approach 2:
The patent changes the spatial arrangement parameter by mounting microphones on opposite sides of a thin PCB with diaphragms facing each other at a distance equal to the PCB thickness. This parameter optimization (using minimal PCB thickness) reduces the device volume while maintaining the tetrahedral geometry's acoustic measurement capabilities.
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
Enables efficient separation of acoustic signals from multiple sources in consumer devices, providing directional sound reception while reducing manufacturing costs and size constraints, making it applicable in compact devices such as mobile phones and hearing aids.
Implementation Method 1
a sensor array comprising a plurality of pressure sensors and a processor arranged to receive signals from the sensors
Implementation Method 2
derive from them a series of sample values of directional pressure gradient, identify a plurality of frequency components of the signals, and define an associated direction for each frequency component
Data Source
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Figure 6~9
AI summary
A system for directionally selective sound reception comprises an array of pressure sensors each arranged to output a pressure signal indicative of pressure, and processing means arranged to receive the pressure signals, identify a plurality of frequency components of the signals, identify at least one source direction, and identify at least one of the components as coming from the source direction. The sensor array comprises support means having two opposite sides and four sensors, at least one of the sensors being supported on each of the sides of the support means.