Hearing Device Sound Source Localization via Time Delay Compensation
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Solution Overview
Problem
Hearing devices for spouse microphone systems lack localization cues due to the absence of intra-aural time difference (ITD) or intra-aural level difference (ILD) in the microphone signal, preventing users from determining the source of sound.
Innovation Solution
A hearing device and method that estimate and apply a time delay between the microphone and transceiver output signals to create localization cues, utilizing a processing unit to determine and apply time shifts, allowing for the combination of signals to enhance sound localization and signal-to-noise ratio through the precedence effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spouse microphone signals are transmitted wirelessly to hearing devices, then the signal-to-noise ratio is improved, but sound source localization capability deteriorates due to lack of ITD and ILD cues
Solution Approach 1:
The system performs preliminary actions by capturing acoustic signals with hearing device microphones before wireless transmission of spouse microphone signals, ensuring that localization cues are preserved in the original acoustic path. The microphones capture the sound as it naturally reaches the user's ears, maintaining ITD and ILD information that will be used later for localization.
Solution Approach 2:
The system merges the spouse microphone signal (with high signal-to-noise ratio) with the hearing device microphone signal (with localization cues) by combining them in the audio processing pipeline. This combination allows the benefits of both signals to coexist - the clean transmitted audio and the spatial localization information from the acoustic capture.
2Loss of information
If time delay is applied to spouse microphone signals to create localization cues, then sound source localization is improved, but timing synchronization between signals deteriorates
Solution Approach 1:
The system changes the time parameter of the spouse microphone signal by applying a calculated time delay that matches the hardware processing delay. This delay adjustment ensures that the transmitted signal arrives at the user's ear at the same time as the signal captured by the hearing device microphones, maintaining temporal synchronization while preserving localization cues.
Solution Approach 2:
The system uses feedback from the measured hardware delay in the audio processing chain to adjust the time delay applied to the spouse microphone signal. By measuring the actual delay introduced by the processing unit and other components, the system can compensate for it and achieve precise timing synchronization between the transmitted and acoustic signals.
3Loss of time
If hardware delays in audio processing are compensated, then signal synchronization is improved, but system complexity increases
Solution Approach 1:
The system performs self-service by automatically measuring its own hardware delay through correlation analysis of the acoustic signal and the transmitted signal. The processing unit calculates the time shift between signals and applies appropriate compensation without requiring external calibration or complex manual configuration, making the system self-adjusting and relatively simple to implement.
Data Source
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AI summary
A hearing device includes: a processing unit; a transceiver connected to the processing unit and being configured for outputting a transceiver output signal representative of a first audio signal to form a first input signal for the processing unit; and a microphone connected to the processing unit for converting a second audio signal into a microphone output signal to form a second input signal for the processing unit; wherein the processing unit is configured to: estimate a time shift between the microphone output signal and the transceiver output signal, determine a time delay based on the time shift, and use the time delay to obtain a summing signal.