Binaural Hearing Signal Processing with Position-Dependent HRTF Compensation
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Solution Overview
Problem
Existing binaural hearing systems face inaccuracies in global direction-dependent signal processing due to local pre-processing that does not account for head-related transfer functions, leading to spatial distortion.
Innovation Solution
A method for operating a hearing system that includes generating pre-processed signals using head-related transfer functions and position-related transfer functions to minimize spatial distortion in local pre-processing, allowing for accurate direction-sensitive signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If local pre-processing is applied to microphone signals in each hearing device, then noise reduction and signal enhancement are improved, but spatial accuracy in global direction-dependent signal processing deteriorates due to distortion of head-related transfer functions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing head-related transfer functions (HRTFs) for multiple possible positions of the second hearing device relative to the user's head. Before global direction-dependent signal processing occurs, the system selects the appropriate HRTF based on the actual position, thereby preparing the correct spatial transformation in advance to compensate for local pre-processing effects and maintain spatial accuracy.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the head-related transfer function parameters based on the detected position of the second hearing device. The system changes the HRTF parameters (such as time delays and attenuation factors) to match the actual spatial configuration, thereby compensating for the distortion introduced by local pre-processing and restoring accurate spatial information for global processing.
2Measurement precision
If head-related transfer functions are used for global direction-dependent signal processing, then spatial accuracy is improved, but device complexity increases due to the need to account for multiple microphone positions and individual HRTFs
Solution Approach 1:
The patent applies segmentation by dividing the complex task of spatial processing into two independent parts: local pre-processing performed separately in each hearing device, and global direction-dependent processing performed using the pre-processed signals. This segmentation allows each part to be optimized independently, reducing overall complexity while maintaining spatial accuracy through the use of position-specific HRTFs in the global processing stage.
Solution Approach 2:
The patent reduces complexity through preliminary action by pre-calculating and storing head-related transfer functions for multiple predetermined positions of the second hearing device. This preparation work is done in advance, so during actual operation the system only needs to select the appropriate pre-computed HRTF based on the detected position, significantly reducing the real-time computational complexity of global direction-dependent signal processing.
3Ease of operation
If the position of the second hearing device is not considered, then device operation is simplified, but spatial distortion increases leading to inaccurate sound localization
Solution Approach 1:
The patent applies dynamics by making the head-related transfer function selection adaptive and position-dependent. The system dynamically adjusts the HRTF parameters based on the detected position of the second hearing device, allowing the processing to adapt to different operational configurations. This dynamic adjustment maintains high spatial accuracy without requiring complex manual configuration, as the system automatically selects the appropriate HRTF based on actual device positioning.
Data Source
AI summary
A method operates a hearing system that has first and second hearing devices. In the first hearing device, a first reference signal and a first auxiliary signal are generated from an environment sound collected by microphones. A first pre-processed signal is generated by applying a direction-sensitive pre-processing to the first reference and auxiliary signals using first reference and first auxiliary pre-processing coefficients. For the microphones, a respective first reference head related transfer function and first auxiliary head related transfer function are provided, and a first head related transfer function is derived from the first reference and first auxiliary pre-processing coefficients and from the first reference and auxiliary head related transfer functions. For the second hearing device a second pre-processed signal is generated using second microphones, and a second position related transfer function is provided. A direction-sensitive signal processing task is performed on the first and second pre-processed signals.