Hearing Device Signal Prediction for Wireless Transmission Delays
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Solution Overview
Problem
Hearing aids connected to external wireless microphones experience significant signal delays due to audio coding and transmission, leading to issues with audio-visual synchronicity and comb-filter effects, rendering the sound signal useless for real-time processing.
Innovation Solution
A hearing device with a signal predictor that estimates future values of the sound signal based on past values, compensating for transmission delays by predicting and mixing the predicted signal with acoustically received signals to enhance audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless transmission with audio coding is used to transmit sound signals from external microphones to hearing aids, then the sound signal can be transmitted over distance, but significant transmission delays are introduced that cause audio-visual synchronicity issues and comb-filter effects
Solution Approach 1:
The system performs preliminary actions by capturing the sound signal locally with the hearing aid's own microphone and processing it in real-time, while simultaneously receiving the wirelessly transmitted signal. The locally captured signal serves as a reference that is already synchronized with the acoustic environment, allowing the system to pre-process and prepare this signal for combination with the delayed wireless signal.
Solution Approach 2:
The locally captured acoustic signal acts as an intermediary element that bridges the timing gap between the real-time acoustic environment and the delayed wireless transmission. By using this intermediate signal as a reference, the system can align and combine signals from both sources, effectively compensating for the transmission delay without requiring modification to the wireless transmission protocol.
2Reliability
If wirelessly received delayed sound signal is presented to the user, then external sound sources can be amplified, but audio-visual synchronicity is compromised and comb-filter effects occur due to direct sound reaching ear drums earlier
Solution Approach 1:
The system merges two signal sources: the delayed but potentially cleaner wirelessly transmitted signal and the locally captured real-time signal. By combining these signals in a sophisticated mixing process, the system achieves both goals - utilizing the external microphone's sound capture capability while maintaining audio-visual synchronicity through the locally captured reference signal, thereby eliminating comb-filter effects.
Solution Approach 2:
The system dynamically adjusts signal processing parameters including timing alignment, gain levels, and frequency-dependent weighting based on the measured delay and acoustic conditions. By changing these parameters adaptively, the system optimizes the combination of signals to maintain synchronicity and minimize harmful effects while preserving sound quality.
3Loss of time
If signal prediction is used to compensate for transmission delays, then real-time processing can be achieved, but the system complexity increases with additional processing requirements
Solution Approach 1:
Instead of attempting to predict and generate the delayed signal from scratch (which would be computationally intensive), the system creates a copy of the real-time acoustic signal captured by the local microphone. This copied signal serves as a reference that already contains the correct timing information, eliminating the need for complex prediction algorithms while achieving the same goal of delay compensation.
Solution Approach 2:
The system uses feedback from the locally captured signal to continuously monitor and adjust the processing of the wirelessly received signal. By comparing the timing and characteristics of the local reference signal with the incoming wireless signal, the system can dynamically adjust alignment and processing parameters, achieving robust delay compensation without requiring overly complex predictive models.
Data Source
AI summary
A hearing device, e.g. a hearing aid, comprises a) at least one input transducer for converting sound in the environment of the hearing device to respective at least one acoustically received electric input signal or signals representing said sound; b) a wireless receiver for receiving an audio signal from a wireless transmitter of a sound capturing device for picking up sound in said environment and providing a wirelessly received electric input signal representing said sound; and c) a processor configured c1) to receive said at least one acoustically received electric input signal or signals, or a processed version thereof; c2) to receive said wirelessly received electric input signal; and c3) to provide a processed signal. The processor comprises a signal predictor for estimating future values of said wirelessly received electric input signal in dependence of a multitude of past values of said signal, thereby providing a predicted signal. The hearing device further comprises d) an output transducer for presenting output stimuli perceivable as sound to the user in dependence of said processed signal from said processor, or a further processed version thereof. The processor is configured to provide said processed signal in dependence of the predicted signal or a processed version thereof 1) alone, or 2) mixed with said at least one acoustically received electric input signal or signals, or a processed version thereof. A hearing device comprising an earpiece and a separate audio processing device is further disclosed. The invention may e.g. be used in hearing devices in wireless communication with audio capture devices in an immediate environment of the user wearing the hearing device.