Binaural Hearing Aid Spatial Audio Processing
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Solution Overview
Problem
Hearing devices struggle to provide accurate spatial acoustics and localization in echoing spaces, limiting the ability of users to understand speech and enjoy multi-channel audio experiences like 5.1 Dolby surround sound due to the positioning of microphones over the concha and interference from spatial acoustics.
Innovation Solution
A method for generating a dual-channel audio signal from a multi-channel audio signal with at least three individual channels, adjusting signal levels using head transmission functions to simulate improved spatial acoustics, incorporating adaptive filtering to account for the wearer's position and orientation, and considering the acoustic effects of the skull and pinna, allowing for natural perception and dynamic sound reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microphones are positioned over the concha for BTE hearing devices, then the device structure is simplified and easier to manufacture, but spatial localization ability deteriorates due to loss of pinna transmission properties
Solution Approach 1:
The patent applies head-related impulse response (HRIR) filtering to copy and simulate the acoustic transmission properties of the pinna, head, and torso. By convolving the microphone signals with pre-recorded or synthesized HRIRs, the system recreates the spectral and temporal characteristics that would normally be provided by the pinna's physical structure, thereby restoring spatial localization cues without requiring microphones to be positioned within the pinna.
2Object-affected harmful factors
If direct transmission of audio material is used via radio link, then interfering spatial acoustics are reduced, but spatial impression and localization ability deteriorate because each hearing device receives only one mono channel
Solution Approach 1:
The patent segments the stereo audio signal into separate left and right channel signals, processes each channel independently through dedicated HRIR filtering paths, and then combines them for binaural output. This segmentation allows each ear to receive processed signals with appropriate spatial characteristics, restoring the spatial impression that would otherwise be lost in mono transmission while maintaining the benefit of direct transmission that eliminates room acoustic interference.
3Measurement precision
If multi-channel audio signals are processed with spatial impulse response convolution, then spatial acoustics are enhanced, but speech understanding deteriorates in echoing spaces
Solution Approach 1:
The patent dynamically adjusts parameters of the HRIR filtering process based on the acoustic environment and signal type. By modifying the impulse response characteristics, filtering strength, and signal level parameters, the system optimizes the balance between preserving spatial acoustics and maintaining speech intelligibility, reducing excessive reverberation effects that would otherwise degrade speech understanding in echoing spaces.
Data Source
AI summary
Wearers of hearing apparatuses and in particular of hearing device systems having two speakers are to be able to enjoy the experience of spatial multi-channel reproduction. Provision is accordingly made to generate a dual-channel audio signal for a binaural hearing apparatus comprising a multi-channel audio signal having at least three individual channels. Accordingly at least one spatial impression-influencing signal level in at least one of the individual channels is changed, and a signal of at least one of the individual channels is connected with signals of the remaining individual channels to the dual-channel audio signal. A corresponding hearing apparatus and in particular a corresponding hearing device have a transformation system that takes over this preprocessing from the multi-channel audio signal to the dual-channel audio signal.