Hearing Aid Receiver Subsonic Filtering
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Solution Overview
Problem
Hearing aids face challenges in effectively reducing occlusion effects caused by subsonic signals from jaw motion, leading to artefacts and wasted battery energy due to high amplitude sound pressure levels, which existing technologies have not adequately addressed.
Innovation Solution
A hearing aid design incorporating a receiver with extended low frequency response and static pressure capability, combined with defined subsonic filtering, to improve occlusion suppression by attenuating subsonic energy without overloading the output amplifier or receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If occlusion suppression is implemented using conventional receivers, then low frequency sound emission is achieved, but subsonic energy from jaw motion overloads the output amplifier and receiver, causing artefacts and wasting battery energy
Solution Approach 1:
The patent extracts and removes subsonic energy components (below 10 Hz) from the signal path using a subsonic filter before the signal reaches the output amplifier and receiver. This prevents the harmful subsonic energy from jaw motion from overloading these components, thereby eliminating artefacts and reducing wasted battery energy while maintaining effective occlusion suppression in the audible frequency range
Solution Approach 2:
The patent changes the frequency response parameters of the receiver by selecting a receiver with extended low frequency response and static pressure capability, specifically designed to handle frequencies down to and including subsonic ranges. This parameter change allows the receiver to operate efficiently without being overloaded by subsonic energy, resolving the contradiction between maintaining low frequency output capability and preventing overload
2Adaptability or versatility
If a receiver with extended low frequency response is used, then subsonic energy handling capability is improved, but dynamic range may be consumed by high amplitude subsonic signals
Solution Approach 1:
The patent applies preliminary action by filtering out subsonic energy components before they enter the main signal processing path and reach the output amplifier and receiver. The subsonic filter is positioned upstream in the signal chain, preemptively removing problematic frequencies and preventing them from consuming dynamic range, thereby preserving the full dynamic range for audible frequency signals
Solution Approach 2:
The patent segments the frequency spectrum by separating subsonic frequencies (below 10 Hz) from audible frequencies using a subsonic filter. This segmentation allows the system to handle different frequency ranges independently, with the subsonic filter managing the problematic low frequency components and the main audio processing chain managing audible frequencies, thus preventing dynamic range consumption by subsonic signals
3Object-generated harmful factors
If subsonic filtering is applied, then artefacts are reduced, but low frequency output capability must be maintained
Solution Approach 1:
The patent applies local quality by implementing frequency-selective filtering that targets only the specific problematic subsonic range (below 10 Hz) while leaving the audible low frequency range (above 10 Hz) unaffected. The subsonic filter is designed with a cutoff frequency that precisely separates harmful subsonic energy from useful low frequency audio signals, thereby reducing artefacts while maintaining low frequency output capability
Solution Approach 2:
The patent changes the frequency response parameters of the overall system by combining a receiver with extended low frequency response with a subsonic filter having a specific cutoff frequency. This parameter configuration allows the system to maintain strong output in the audible low frequency range while attenuating only the harmful subsonic components, thus resolving the contradiction between artefact reduction and low frequency output maintenance
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 significantly reduces occlusion cancellation artefacts and preserves dynamic range, ensuring effective occlusion cancellation without audible sound artefacts or excessive battery drain, while maintaining low frequency output capability.
Implementation Method 1
A receiver (110) is adapted for receiving and converting a combined signal into an acoustic output signal
Implementation Method 2
an ear canal microphone (109) adapted for converting ear canal sound pressure into an ear canal signal
Implementation Method 3
an ambient microphone (102) adapted for receiving and converting environmental sound into an electronic input signal
Data Source
AI summary
A hearing aid includes an ambient microphone configured to receive and convert environmental sound into an electronic input signal, a hearing loss processor configured to compensate the electronic input signal in accordance with a hearing loss of a user of the hearing aid, and to generate an electronic output signal, a receiver, an ear canal microphone configured for converting ear canal sound pressure including subsonic energy into an ear canal signal, an occlusion suppressor connected for reception and processing of the ear canal signal, and for transmitting an occlusion suppression signal, a signal combiner configured for combining the occlusion suppression signal and the electronic output signal to form a combined signal, and for transmitting the combined signal to the receiver, and a subsonic filter for filtering subsonic energy, wherein the receiver is configured to receive the combined signal, and convert the combined signal into an acoustic output signal.