On-Ear Headset Detection via Acoustic Probe Signals
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Solution Overview
Problem
Existing headset technologies face challenges in accurately determining whether a headset is being worn, leading to false positives due to noise interference and hardware costs associated with dedicated sensors.
Innovation Solution
A signal processing device and method utilizing multiple microphones to derive and normalize signal feature measures, variably weight them based on detected conditions, and combine them to produce an output indication of whether the headset is on ear, employing an inaudible acoustic probe signal and dynamic weighting to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated sensors (capacitive, optical, or infrared) are used for on-ear detection, then detection accuracy is improved, but hardware cost and power consumption increase
Solution Approach 1:
The patent replaces dedicated non-acoustic sensors (capacitive, optical, infrared) with acoustic sensing using existing microphones. The system uses acoustic probe signals and analyzes acoustic characteristics (reverberation, echo, frequency response) to detect on-ear status, eliminating the need for separate sensor hardware and reducing power consumption while maintaining detection accuracy
Solution Approach 2:
The patent makes the existing microphones serve dual functions: both audio processing (ANC, transparency mode) and on-ear detection. By analyzing acoustic characteristics from the same microphones used for audio functions, the system eliminates dedicated detection sensors and reduces overall hardware complexity and power requirements
2Device complexity
If sense microphone signal power is used for on-ear detection, then hardware cost is reduced, but false positives occur due to noise interference
Solution Approach 1:
The patent plays an inaudible acoustic probe signal through the speaker before analyzing the microphone input. This preliminary action creates a known reference signal that allows the system to detect on-ear status by analyzing the acoustic characteristics (reverberation, echo) of the probe signal, rather than relying on ambient noise that may cause false positives
Solution Approach 2:
The system analyzes the feedback from the microphone to the played probe signal by examining acoustic characteristics such as reverberation time, echo, and frequency response changes. This feedback analysis provides reliable on-ear detection by comparing the acoustic signature when the headset is on versus off the ear, eliminating false positives from ambient noise
3Device complexity
If acoustic probe signal with fixed frequency is used, then implementation is simple, but detection accuracy decreases in noisy environments
Solution Approach 1:
The patent transitions from fixed-frequency probe signals to multi-frequency or swept-frequency probe signals. By using multiple frequencies or frequency sweeps, the system can better distinguish on-ear detection characteristics from ambient noise, improving accuracy while maintaining reasonable implementation complexity through standard audio processing techniques
Solution Approach 2:
The patent analyzes multiple acoustic characteristics (reverberation time, echo, frequency response, spectral content) instead of relying on a single frequency measurement. This multi-dimensional analysis approach improves detection accuracy by examining the acoustic signature from multiple angles, making the detection more robust to noise interference
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 enhances the accuracy of on-ear detection while reducing hardware costs and power consumption by relying solely on acoustic means, effectively distinguishing between being on and off ear even in noisy environments.
Implementation Method 1
an acoustic probe signal is played out via a speaker of the headset and an indication of whether the headset is on ear is derived from a microphone signal received from a microphone of the headset in response to the played out acoustic probe signal
Data Source
AI summary
A method and device for detecting whether a headset is on ear. Microphone signals from a plurality of microphones are used to derive a plurality of signal feature measures, which are normalized to a common reference scale. The signal feature measures are weighted based upon detected signal conditions in the microphone signals. The normalized and variably weighted signal feature measures are then combined to produce an output indication of whether a headset is on ear.