Active Interference Cancellation in Hearing Aids
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Solution Overview
Problem
Hearing assistive devices, such as hearing aids, experience significant interference from electronic sources like digital cell phones and other digital devices, which degrade the quality of the audible signal due to RF and magnetic field interference, leading to reduced performance and user dissatisfaction.
Innovation Solution
An active interference cancellation method and apparatus that generates a replica of the interference waveform, inverts it, and combines it with the composite signal to cancel out the interference, using real-time monitoring, RF antennas, or stored profiles, allowing the device to operate in either cancellation or non-cancellation modes based on user input or sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hearing assistive devices operate in environments with digital wireless devices, then communication functionality is enabled, but electronic interference degrades signal quality and device performance
Solution Approach 1:
The patent captures the harmful RF interference signal and converts it into a useful cancellation waveform. The interference signal is demodulated to extract its characteristics, then an inverted replica is generated and combined with the original signal to cancel the interference, transforming the harmful RF energy into a beneficial noise-reduction mechanism
Solution Approach 2:
The patent introduces an intermediary RF antenna and demodulation system that acts as a mediator between the harmful RF interference and the audio signal processing chain. This intermediary captures the RF signal separately, processes it to extract interference characteristics, and uses these characteristics to generate cancellation waveforms that are then combined with the microphone signal
2Productivity
If hearing aids process composite signals containing both desired and interference waveforms, then all signals are amplified and output, but the audible quality of the desired signal is diminished
Solution Approach 1:
The patent extracts the interference waveform from the composite signal by using an RF antenna to capture the RF interference separately. The demodulation process extracts the interference characteristics, which are then used to generate a cancellation waveform that removes only the interference component while preserving the desired audio signal
Solution Approach 2:
The patent implements a feedback mechanism where the RF interference signal is continuously monitored, demodulated, and used to generate real-time cancellation waveforms. The cancellation waveform is fed back into the signal processing chain and combined with the original composite signal, creating a closed-loop system that actively suppresses interference
3Measurement precision
If RF interference is captured and demodulated by hearing aid circuitry, then interference signal is generated, but the interference is then amplified and delivered to the user
Solution Approach 1:
The patent applies preliminary anti-action by generating the cancellation waveform before the interference reaches the user's ear. The RF interference is captured and demodulated, the cancellation waveform is created by inverting the interference signal, and this cancellation waveform is combined with the composite signal in advance, preventing the interference from being amplified and delivered to the user
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 solution effectively eliminates interference, enhancing the quality of the audio output by isolating the desired signal from unwanted electromagnetic interference, thereby improving the user experience with hearing assistive devices.
Implementation Method 1
When a hearing aid operates in an environment that includes a modulated RF field or a fluctuating magnetic field, undesired interference may be induced in the hearing aid circuitry as the varying fields are detected and processed as electrical signals by the hearing aid
Data Source
AI summary
An apparatus and method for active cancellation of interference at a hearing assistive devices are presented. The apparatus includes an interference cancellation circuit for cancelling an interference component of a composite signal, and an activator circuit for enabling interference cancellation circuit. The interference cancellation circuit generates an estimated replica of the interference from an interference profile, inverts the replica to form a cancellation waveform, then adds the cancellation waveform to the composite signal to cancel the interference component. An interference profile can be provided by performing a training sequence on a composite signal to detect a repetitive signal and building a profile using its parameters, retrieving a profile stored in memory, or using an antenna to capture an RF signal. The activator circuit may enable the interference cancellation circuit when RF energy is detected, when composite signal characteristics match one or more stored profiles, or in response to user input.