Hearing Device Feedback Estimation Using Startup Jingle
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Solution Overview
Problem
Existing hearing devices face challenges in accurately determining and controlling the transfer function of the acoustic feedback path, leading to unpredictable feedback-generated oscillations, especially during device insertion and environmental changes.
Innovation Solution
The method involves using a hearing device with a signal processor that generates predetermined audio signals to estimate the transfer function of the acoustic feedback path, allowing for initial and subsequent adjustments to prevent oscillations by comparing these signals and adjusting the acoustic gain accordingly, both during start-up and fitting sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hearing device operates at high acoustic gain to improve hearing capability, then the hearing capability is enhanced, but feedback-generated oscillations occur
Solution Approach 1:
The system performs preliminary estimation of the acoustic feedback path transfer function during a test period before normal operation begins. This advance knowledge allows the system to pre-configure feedback suppression settings that prevent oscillations from occurring in the first place, rather than reacting to them after they arise.
Solution Approach 2:
The system uses feedback from the acoustic path (microphone picking up loudspeaker output) to estimate the transfer function and determine appropriate feedback suppression parameters. This feedback mechanism enables the system to adaptively control the acoustic gain to prevent oscillations while maintaining hearing enhancement.
2Measurement precision
If the transfer function is estimated during normal operation to improve accuracy, then the estimate becomes more accurate, but feedback oscillations occur during estimation
Solution Approach 1:
The system performs the transfer function estimation during a dedicated test period before normal hearing enhancement operation begins. This preliminary estimation avoids the problem of oscillations during estimation while still providing accurate transfer function data for subsequent operation.
Solution Approach 2:
The system uses a periodic test signal (sweep signal or multi-tone signal) played during the test period to excite the acoustic path and measure its transfer function. This periodic excitation allows accurate measurement without causing harmful oscillations that would occur with continuous estimation during normal operation.
3Adaptability or versatility
If the hearing device is inserted into the ear to provide hearing enhancement, then the hearing capability is improved, but the acoustic feedback path changes causing unpredictable oscillations
Solution Approach 1:
The system performs transfer function estimation after the hearing device is inserted into the user's ear, during a test period before normal operation. This ensures the measurement reflects the actual in-ear acoustic conditions, including the ear canal geometry and seal characteristics, leading to reliable and predictable feedback suppression throughout subsequent use.
Solution Approach 2:
The system adapts to the dynamic changes in the acoustic feedback path that occur when the device is inserted into the ear. By measuring the transfer function in the actual in-ear condition rather than using pre-stored values, the system dynamically adjusts to the unique acoustic characteristics of each user's ear canal.
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 effectively reduces feedback-generated oscillations by providing accurate initial and ongoing estimates of the transfer function, enabling better control of acoustic gain and improving the fitting process, thereby enhancing the user experience and device performance.
Implementation Method 1
picks up the acoustic feedback from the loudspeaker to the microphone
Data Source
AI summary
The invention relates to a method for determining an estimated transfer function of an acoustic feedback path during fitting of a hearing device, which receives acoustic signals from an individual's surroundings, modifies the acoustic signals electronically and transmits the modified acoustic signals into the individual's ear or ear canal. In order to save resources in the hearing device, the hearing device reuses a start-up jingle for determining an estimated transfer function during a fitting session upon reception of a predefined message from a fitting apparatus.