Active Noise Cancellation Calibration Using Extracted Speaker
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Solution Overview
Problem
Component tolerance and assembly issues in ANC systems of portable audio devices lead to variability in microphone and speaker sensitivity, affecting noise cancellation performance, and existing calibration methods are complex and time-consuming.
Innovation Solution
A method for calibrating ANC-enabled portable audio devices involves playing a calibration sound by a separate calibrated speaker to measure and compare audio signal levels, computing calibration values for microphones and speakers, and storing these values for compensation, allowing for improved noise cancellation without requiring a microphone or ear simulator in the test station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional calibration methods are used for ANC systems, then manufacturing precision of microphone and speaker sensitivity can be achieved, but the calibration process becomes complex and time-consuming
Solution Approach 1:
The patent extracts the calibration function from a complex test station with multiple microphones and ear simulators, leaving only a single calibrated speaker. This simplifies the calibration equipment while maintaining manufacturing precision through the extracted essential function of acoustic signal generation.
Solution Approach 2:
The portable audio device performs self-calibration by measuring its own microphones' response to the calibration speaker's sound. The device's processing element automatically computes calibration values for each microphone, eliminating the need for complex external calibration equipment and manual intervention.
2Measurement precision
If traditional calibration methods with multiple microphones and ear simulators are used, then measurement precision of microphone sensitivity can be achieved, but the calibration time increases significantly
Solution Approach 1:
The patent removes unnecessary components (multiple microphones, ear simulators) from the calibration system, retaining only the essential calibrated speaker. This extraction reduces the calibration process to a single acoustic measurement step, dramatically reducing calibration time while preserving measurement precision.
Solution Approach 2:
The calibration speaker continuously generates the calibration sound signal, allowing all microphones to be calibrated simultaneously in a single continuous measurement process rather than requiring sequential calibration steps with multiple components.
3Reliability
If a test station with microphone and ear simulator is used for calibration, then reliability of ANC performance can be verified, but the device complexity and cost increase
Solution Approach 1:
The patent extracts and removes the test station's microphone and ear simulator components, relying instead on the portable audio device's own microphones and speakers for calibration. This eliminates the complex test station while maintaining reliability through the device's self-calibration capability.
Solution Approach 2:
The portable audio device serves its own calibration needs using its built-in microphones and speakers, eliminating the requirement for external test station equipment. The device's processing element automatically verifies and adjusts its components' sensitivity, ensuring reliable ANC performance without complex external equipment.
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 approach simplifies the calibration process, reduces complexity and time, and enhances noise cancellation performance by accurately compensating for sensitivity changes in microphones and speakers, leading to increased ANC effectiveness.
Implementation Method 1
playing continuously a calibration sound by a calibrated speaker
Implementation Method 2
measuring a level of an audio signal transduced by the microphone in response to the continuously-played calibration sound
Data Source
AI summary
A method for calibrating an ANC-enabled portable audio device having microphones plays continuously a calibration sound by a calibrated speaker of a test station separate from the device. For each microphone of all the microphones, a microphone calibration value is computed using a comparison of a predetermined level and a measured level of an audio signal transduced by the microphone in response to the continuously-played calibration sound. The calibration is done without using a microphone of the test station. A processing element of the device may be programmed to make the comparison and computation. The processing element also causes a speaker of the device to generate a second calibration sound, measures a second level while the computed calibration value is applied to one of microphones (e.g., error microphone), and computes a calibration value for the device speaker using a comparison of a predetermined level and the second level.