Ear Biometric SNR Improvement via Dual-Function Audio Stimulus
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Solution Overview
Problem
Ear biometric systems face challenges due to a low signal-to-noise ratio (SNR) in the measured response signal, exacerbated by factors such as noisy environments and poor fitting of earphones, which weakens the biometric features of the acoustic signal.
Innovation Solution
The method involves using audio signals already output to a transducer for dual functions: the first function is unrelated to biometric processing, such as providing speech or media content, and the second function is to apply the same audio as an acoustic stimulus to improve the SNR by aligning the signal with ear resonances and increasing measurement opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the acoustic stimulus has narrow bandwidth and low amplitude to avoid being overbearing on the user, then user comfort is improved, but the signal-to-noise ratio of the measured response signal deteriorates
Solution Approach 1:
The audio signal serves dual functions: (1) providing audio content to the user (speech, media, notifications) and (2) serving as an acoustic stimulus for biometric measurement. This multi-functionality allows the system to use the same audio output for both user enjoyment and biometric data collection, improving SNR without compromising comfort.
Solution Approach 2:
The system continuously measures the ear canal response during ongoing audio playback rather than requiring separate measurement sessions. The acoustic stimulus is continuously present through media playback, virtual assistant interactions, or notifications, allowing continuous biometric measurement without interrupting the user experience.
2Measurement precision
If the acoustic stimulus amplitude is increased to improve the signal-to-noise ratio, then measurement precision is improved, but user comfort deteriorates as the signal becomes overbearing
Solution Approach 1:
The system repurposes the audio signal already being output to the user for biometric measurement purposes. By using the same audio content that the user wants to hear (music, speech, notifications) as the acoustic stimulus, the system achieves high SNR without requiring additional high-amplitude test signals that would discomfort the user.
3Measurement precision
If multiple separate acoustic stimuli are applied to improve measurement accuracy, then biometric feature extraction is improved, but the time required for biometric processing increases
Solution Approach 1:
The system extracts biometric features from audio content that is already being played to the user, eliminating the need for separate measurement time. The same audio signal serves both as entertainment/information and as the basis for biometric measurement, achieving accurate feature extraction without additional time investment.
Solution Approach 2:
The biometric measurement occurs continuously during normal audio playback activities. Rather than requiring dedicated measurement time, the system continuously analyzes the ear canal response to the ongoing audio signal, enabling biometric enrollment and verification to occur during regular media consumption or communication.
4Measurement precision
If the acoustic stimulus bandwidth is increased to improve biometric feature extraction, then measurement precision is improved, but the stimulus becomes more noticeable and potentially overbearing to the user
Solution Approach 1:
The system uses the actual audio content being played to the user (which naturally has appropriate bandwidth for both user enjoyment and biometric measurement) as the acoustic stimulus. This eliminates the need to design separate broadband test signals that might be uncomfortable, while still capturing sufficient biometric information through analysis of the ear canal's frequency response to the audio content.
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 biometric enrolment and authentication by improving the SNR and extending the duration of ear canal response measurement, leading to more reliable biometric data collection.
Implementation Method 1
the ear canal is a resonant system, and therefore one feature which may be extracted from the response signal is the resonant frequency of the ear canal
Data Source
AI summary
A method for use in a biometric process, comprising: for a first function and a second function, applying an acoustic stimulus to a user's ear; and for the second function: receiving a response signal of a user's ear to the acoustic stimulus; and extracting, from the response signal, one or more features for use in a biometric process, wherein the first function is a function other than to induce the response signal for use in the biometric process.