Microphone Directivity Adjustment via Time-Delay Signal Processing
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Solution Overview
Problem
Conventional microphone apparatuses with multiple MEMS microphones face challenges in adjusting directivity effectively, leading to erroneous acoustic signals and low speech-recognition rates due to fixed sound guides and limited size constraints.
Innovation Solution
A microphone apparatus with two MEMS microphones and an integrated circuit that captures acoustic signals, performs time-delay processing, and generates differential signals to dynamically adjust polar patterns, allowing for omni-directional or directional configurations based on sound source distance and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed sound guides are used to extend the distance between microphones, then the signal-to-noise ratio is improved, but the directivity becomes fixed and cannot adapt to changing sound source positions
Solution Approach 1:
The patent implements dynamic directivity adjustment by using an integrated circuit to perform time-delay processing on acoustic signals from multiple microphones. The system can switch between omni-directional and directional patterns based on sound source position, resolving the contradiction between fixed structure for SNR improvement and adaptability for varying sound source positions.
Solution Approach 2:
The system changes the time delay parameter dynamically to adjust the polar pattern. By varying the time delay applied to signals from different microphones, the system can transform between omni-directional and directional patterns, maintaining adaptability while using a fixed physical microphone arrangement.
2Reliability
If multiple microphones are deployed to improve sensitivity and noise-to-signal ratio, then the performance is enhanced, but the total size of the microphone apparatus increases
Solution Approach 1:
The patent combines multiple microphones and signal processing functions into a single integrated circuit package. The microphone apparatus includes a microphone cover, circuit board, and integrated circuit that work together as a compact unit, achieving both improved noise-to-signal ratio through multiple microphones and small size through integration.
Solution Approach 2:
The system nests the integrated circuit within the microphone housing, with the circuit board and microphones arranged in a compact configuration. The first and second microphones are positioned within the microphone cover, creating a nested structure that minimizes overall size while maintaining multiple sensing elements.
3Measurement precision
If the distance between microphones is increased to improve directivity, then the polar pattern accuracy is enhanced, but the microphone apparatus size increases
Solution Approach 1:
The patent replaces the mechanical approach of physically spacing microphones far apart with an electronic signal processing approach. The integrated circuit applies time-delay processing to simulate the effect of larger microphone spacing, achieving accurate polar patterns without increasing the physical size of the apparatus.
Solution Approach 2:
The integrated circuit acts as an intermediary that processes the acoustic signals from the microphones. By introducing time-delay processing as an intermediate step, the system can achieve the effect of increased microphone spacing without actually increasing the physical distance between microphones.
Data Source
AI summary
A microphone apparatus is provided. The microphone apparatus includes a microphone cover; a circuit board, an integrated circuit, a first microphone, and a second microphone. The integrated circuit is coupled to the microphone cover and the circuit board to form a first chamber and a second chamber. The first microphone is placed inside the first chamber and configured to capture a first acoustic signal from a sound source. The second microphone is placed inside the second chamber and configured to capture a second acoustic signal from the sound source. The first microphone and the second microphone have the same sensitivity, phase, and omni-directivity. The integrated circuit performs a time-delay process on the second acoustic signal and subtracts the time-delayed second acoustic signal from the first acoustic signal to generate a differential signal. The integrated circuit forms a polar pattern of the microphone apparatus according to the differential signal.