Hearing Instrument T-Coil Noise Synchronization
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Solution Overview
Problem
Hearing instruments with T-coil antennas face noise interference from duty-cycled components like RF transceivers, leading to audible distortions due to magnetic field induction, which existing noise reduction methods like load balancing and noise shaping cannot effectively address without compromising the transceiver's functionality.
Innovation Solution
The hearing instrument communicates the interference points in time to the audio signal processing unit, applying a click removal treatment, such as static filtering, adaptive noise cancellation, or packet loss concealment, to eliminate noise during these points, specifically using a high pass filter or adaptive noise canceller synchronized by the RF unit's trigger signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If duty cycling mode is used for RF transceiver, then energy consumption is reduced, but magnetic field noise is induced in T-coil antenna
Solution Approach 1:
The system performs preliminary action by predicting the timing of duty cycle transitions and pre-positioning filter coefficients in a buffer before the actual interference occurs. This allows the audio signal processing to be optimized in advance for the upcoming noise event, reducing the impact of magnetic field induction during T-coil operation.
Solution Approach 2:
The invention implements dynamic adaptation by continuously adjusting the filter coefficients based on the actual duty cycling pattern of the RF transceiver. The system dynamically updates the predicted transition times and recalibrates the filter parameters to match the actual noise characteristics, making the noise cancellation adaptive rather than static.
2Object-affected harmful factors
If load balancing or noise shaping is applied, then magnetic field noise is reduced, but transceiver functionality is hampered
Solution Approach 1:
The invention extracts and isolates the noise cancellation function from the transceiver's core operational modes. By using a separate audio signal processing path with adaptive filtering that operates independently of the transceiver's duty cycling control, the system removes the harmful magnetic field noise effects without altering or constraining the transceiver's functionality for remote control or other purposes.
3Object-affected harmful factors
If RF transceiver operates with low duty cycle, then T-coil audio signal is less distorted, but click signals remain audible
Solution Approach 1:
The system implements feedback by continuously monitoring the audio signal for click artifacts and using this information to adjust the filter coefficients in real-time. The audio signal processing unit receives feedback about the actual noise characteristics and adapts the predictive filtering parameters accordingly, creating a closed-loop system that eliminates audible clicks while preserving T-coil audio quality.
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 efficiently removes noise-induced distortions from the T-coil audio signal, improving audio clarity by synchronizing noise reduction with the duty cycling operation of the RF unit, thereby enhancing user experience without hampering the transceiver's functionality.
Implementation Method 1
a ferrite coil which is sensitive not only to the base band audio signal to be picked up from the telephone device transducer
Implementation Method 2
such AC content is reduced in hearing instruments by either load balancing or noise shaping or large bulk capacitors. Thus, peaks of the current drawn by the transceiver may induce a magnetic field which, in turn, may be picked up by the T-coil antenna
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
There is provided a hearing instrument comprising a T-coil antenna (14) for picking up an inductively transmitted base-band audio signal, an audio signal processing unit (16) for processing the picked-up T-coil audio signal, and an output transducer (18) for stimulation of the user's hearing according to the processed audio signals, and a functional unit (22) being adapted to operate in a duty cycling mode and to communicate to the audio signal processing unit the interference points in time at which the functional unit is switched from its inactive state to its active state and/or from its active state to its inactive state, wherein the audio signal processing unit is adapted to apply a click removal treatment to the T-coil audio signal during said interference points in time at time at which the functional unit is switched to and/or from its active state.