Earbud Position Detection via Speech Vibration for Microphone Selection

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Solution Overview

Problem

Existing audio devices face challenges in accurately determining whether earbuds are positioned in a user's ears, leading to suboptimal microphone selection for beamforming, especially in varying environmental conditions and user orientations.

Innovation Solution

The solution involves detecting user speech vibrations using both microphones and accelerometers in the earbuds, employing voice activity detection (VAD) and normalized cross-correlation techniques to determine earbud position, and selectively choosing microphones for beamforming based on this information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If gravitational-based detection methods are used to determine earbud position, then the device complexity is reduced, but the measurement precision deteriorates due to errors in varying user orientations

Engineering Contradiction:

Improvedetection method complexityVSAvoidearbud position detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces gravitational-based mechanical detection with voice vibration detection using accelerometers. Instead of relying on gravity direction to infer earbud position, the system detects vibrations caused by user speech at the accelerometers in the earbuds. This substitution eliminates orientation-dependent errors while maintaining relatively simple device architecture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from gravitational force direction to vibration frequency and amplitude characteristics. By analyzing voice-induced vibrations at the accelerometers, the system can determine earbud position independent of user orientation, thereby improving measurement precision without significantly increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If all microphones are used for beamforming regardless of earbud position, then the device complexity is reduced, but the signal-to-noise ratio deteriorates due to inclusion of inappropriate microphones

Engineering Contradiction:

Improvemicrophone selection system complexityVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements dynamic microphone selection based on real-time earbud position detection. The system continuously monitors accelerometer data to determine which earbuds are properly positioned in the user's ears, and dynamically adjusts which microphones are activated for beamforming. This dynamic adaptation improves signal-to-noise ratio by ensuring only appropriate microphones are used, while the complexity increase is managed through algorithmic control rather than additional hardware.

Inventive Principle:

Principle #15Dynamics

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 user voice detection and beamforming by ensuring that only the appropriate microphones are used, improving signal-to-noise ratio and reducing errors associated with gravitational-based detection methods.

Implementation Method 1

detecting a user's voice at microphones and accelerometers of the headset... detecting user speech vibrations in accelerometers in the earbuds

Methodology Applied

Scientific EffectVibration: Vibration

Implementation Method 2

detecting user speech vibrations at the microphones... microphone based voice activity detection (VAD)

Methodology Applied

Scientific EffectSound: Sound

Data Source

PatentUS9516442B1Detecting the positions of earbuds and use of these positions for selecting the optimum microphones in a headset

Publication Date: 2016.12.06 APPLE INC

AI summary

Embodiments of the invention determine whether speaker earbuds of a headset are positioned in a user's ears. The headset may be a “Y” shaped headset with two earbuds having speakers and a plug for insertion into a jack of the audio device. Multiple microphones are located on wired lengths to the earbuds and a common wire between the lengths and the plug, to receive speech from the user's mouth. Each earbud may have a front and rear microphone, and an accelerometer. Embodiments can detect user speech vibrations at one or more of the microphones, and in the accelerometers in the earbuds. Based on these detections, it can be determined whether one or both of the earbuds are in user's ears. To provide more accurate beamforming, when only one of the earbuds is in the user's ears, only the microphones leading to that earbud are selected for beamforming input.