Mid-Side Audio Processing for Hearing Aid Computational Efficiency
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Solution Overview
Problem
Traditional hearing aid processors face computational strain in performing sound augmentation for stereo audio devices, as they require processing both left and right channels independently, leading to inefficiencies and potential loss of sound quality.
Innovation Solution
The method involves encoding left and right audio signals into mid and side channels, processing these channels separately using dynamic range compression and spectral decomposition, and recombining them to reduce computational workload while maintaining sound integrity, allowing for efficient and high-quality sound augmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sound augmentation is performed on both left and right channels independently, then sound quality is maintained, but computational workload increases significantly
Solution Approach 1:
The patent combines the left and right audio channels into a single mid channel for sound augmentation processing. The mid channel is generated by summing the left and right channels, and the sound augmentation is applied once to this combined signal rather than independently to each channel, thereby reducing computational workload while preserving perceptual sound quality.
Solution Approach 2:
The patent segments the audio processing into two distinct pathways: a mid channel pathway that receives full sound augmentation processing, and a side channel pathway that receives minimal processing. This segmentation allows the computationally intensive sound augmentation to be applied only once to the mid channel rather than duplicated across both stereo channels.
2Productivity
If sound augmentation is performed on a single mid channel, then computational workload is reduced, but sound localization accuracy may be compromised
Solution Approach 1:
The side channel acts as an intermediary that carries spatial information between the mid channel processing and the final stereo output. The side channel is generated by subtracting the right channel from the left channel, preserving inter-channel level differences that are critical for sound localization, and is combined with the processed mid channel to reconstruct the stereo signal with accurate spatial positioning.
3Object-affected harmful factors
If dynamic range compression is applied to the entire frequency spectrum, then hearing strain is reduced, but computational complexity increases
Solution Approach 1:
The patent applies local quality by differentiating the processing applied to different frequency regions. The dynamic range compression is applied selectively to the high-pass filtered portion of the signal (frequencies above a certain threshold) while the low-pass filtered portion (lower frequencies) receives different or no compression processing. This allows hearing strain reduction to be targeted at frequency regions where it is most beneficial while reducing overall computational complexity.
Data Source
AI summary
Disclosed are technologies for processing a surround sound audio signal. The center channel is processed to generate a processed center channel. For each pair of corresponding left and right audio channels, mid and side channel signals are generated by taking the sum and difference of the pair, respectively. The side channel is outputted to a first signal pathway that features a dynamic range compressor. The mid channel is outputted to a second signal pathway and spectrally decomposed into a plurality of sub-band signals. Each sub-band signal is compressed by a dynamic range compressor and transmitted to a gain stage. The compressed sub-band signals are outputted from the gain stage and recombined. The outputs of the first and second signal pathways are then recombined and decoded to produce processed left and right audio signals. Each pair or processed left and right audio signals are output along with the processed center channel.