Microphone Self-Calibration Using Internal Audio Test Signals
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Solution Overview
Problem
Conventional methods for debugging and calibrating audio systems with MEMS microphones require complex setups and external acoustic stimuli, leading to increased test times and user dissatisfaction due to the need for adequate acoustic experience.
Innovation Solution
A system that generates a calibrated output signal internally within the microphone, allowing for tuning and calibration without external audio stimuli, using an electronic indication or invocation signal to invoke a calibration signal generation module, which can be applied to the transducer or directly output, reducing calibration and debugging times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods using external acoustic stimuli are used, then calibration accuracy can be achieved, but calibration time and system complexity increase significantly
Solution Approach 1:
The microphone system performs self-calibration by generating its own test signals internally and measuring its own response, eliminating the need for external calibration equipment and acoustic stimuli. The system uses an integrated calibration signal generator that creates test tones and measures the microphone's frequency and phase response autonomously.
Solution Approach 2:
The patent replaces the mechanical/acoustic calibration setup (external speakers, acoustic chambers, physical measurement equipment) with an electronic calibration system that generates test signals electronically and processes them through digital signal processing circuits, significantly reducing calibration time and complexity.
2Measurement precision
If conventional calibration setups with external acoustic stimuli are used, then accurate frequency and phase response measurement is possible, but device complexity and setup requirements increase
Solution Approach 1:
The calibration signal generator and measurement functions are merged into the microphone system itself, combining the test signal source, under-test device, and measurement equipment into a single integrated unit. This eliminates the need for separate external calibration equipment and simplifies the overall system.
Solution Approach 2:
The microphone system is designed to perform multiple functions: normal audio capture and the additional function of self-calibration. The same microphone element serves both as the device under test and as part of the measurement system, allowing frequency and phase response characterization without requiring dedicated calibration hardware.
3Ease of operation
If conventional calibration methods are used, then downstream signal path elements can be tuned, but the process requires extensive user expertise and time
Solution Approach 1:
The system automatically performs calibration and debugging functions without requiring user intervention or expertise in acoustic measurements. The integrated calibration system autonomously generates test signals, measures responses, and provides feedback for tuning downstream signal path elements, making the process accessible to users without specialized knowledge.
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
Significantly reduces calibration and debugging times by enabling internal signal generation and processing, independent of porting or gasketing configurations, and allows for effective tuning of audio system components without external acoustic energy.
Implementation Method 1
the transducer converts sound energy into an electrical signal
Data Source
AI summary
A microphone that includes a calibration signal generator that generates a calibration signal based upon a received invocation input. The calibration signal has known audio properties. The microphone also includes a transducer that converts sound energy into an electrical signal. An integrated circuit receives the electrical signal from the transducer. An external microphone interface provides the calibration signal to a device external to the microphone.