Earbud Automatic Equalization via Acoustic Feedback
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Solution Overview
Problem
In-ear headphones, or earbuds, exhibit variances in frequency response due to inconsistent positioning, differing ear sizes, and movement, leading to inconsistent audio experience across users.
Innovation Solution
An earbud system with a processor that determines energy ratios between the speaker and microphone signals, selects a shelving filter based on these ratios, and applies it to the audio signal to compensate for occlusions, ensuring a consistent frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If earbuds are used to achieve compact size and ambient noise reduction, then portability and noise isolation are improved, but frequency response consistency deteriorates due to occlusion variances
Solution Approach 1:
The system uses a microphone to capture the audio signal as it is emitted into the user's ear, creating a feedback loop. The processor analyzes the captured signal to determine occlusion characteristics and automatically adjusts the frequency response by applying compensatory filters to the audio output, thereby maintaining consistent frequency response despite varying ear canal occlusions
Solution Approach 2:
The system dynamically changes the audio signal parameters (frequency response characteristics) based on real-time analysis of the occlusion conditions. By adjusting equalization parameters according to the detected occlusion level, the system compensates for the negative effects of ear canal sealing while maintaining the compact earbud design
2Ease of operation
If earbuds are positioned inconsistently in the user's ear, then ease of insertion is improved, but frequency response stability deteriorates
Solution Approach 1:
The feedback mechanism continuously monitors the audio signal emitted into the ear canal and detects changes in occlusion characteristics caused by movement or repositioning. When variations are detected, the system automatically recalibrates the equalization parameters to compensate for the new positioning, maintaining frequency response stability without requiring precise manual placement
3Adaptability or versatility
If the headphone moves in the user's ear due to stress or activity, then comfort and flexibility are improved, but frequency response consistency deteriorates
Solution Approach 1:
The system implements dynamic equalization that continuously adapts to changing occlusion conditions caused by movement, stress, or physical activity. The processor monitors the audio feedback in real-time and automatically adjusts filter parameters to compensate for movement-induced variations, maintaining frequency response consistency while allowing natural earbud movement and flexibility
Solution Approach 2:
Through continuous feedback from the microphone capturing the emitted audio signal, the system detects movement-induced occlusion changes and automatically compensates by adjusting the equalization parameters, thereby maintaining frequency response consistency despite physical activity or stress
Data Source
AI summary
An accessory having an earbud for insertion into a user's ear is disclosed. The earbud may include a speaker and a microphone in which the speaker plays an audio signal for the user and the microphone receives the audio signal. The accessory includes a processor that is coupled to the speaker and the microphone to execute various operations. For example, the operations may include: determining a ratio of an energy estimation of the speaker audio signal to an energy estimation of the audio signal received by the microphone; determining a gain for the speaker audio signal based upon the ratio; based upon the gain, selecting a shelving filter; and applying the shelving filter to the speaker audio signal.