Bandwidth-Normalized Medial Olivocochlear Coding for Noisy Speech
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Solution Overview
Problem
Cochlear implant users face challenges in understanding speech in noisy environments due to the lack of the natural medial olivocochlear reflex, which enhances sound localization and noise reduction in normal hearing individuals.
Innovation Solution
Implement a channel-specific dynamic inhibition adjustment based on a normalized medial olivocochlear reflex model to modulate electrical stimulation signals in bilateral cochlear implants, using a channel-specific dynamic inhibition function to enhance sound perception in noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cochlear implant signal processing is used, then basic sound perception is achieved, but speech recognition in noisy environments deteriorates due to lack of medial olivocochlear reflex
Solution Approach 1:
The patent copies the natural medial olivocochlear reflex mechanism by implementing a contralateral inhibition model that mimics how the natural MOC reflex suppresses neural responses to noise. The signal processor applies contralateral band-pass filtering and inhibition functions to replicate the biological noise reduction pathway, enabling cochlear implant users to achieve speech recognition in noisy environments similar to normal hearing individuals.
Solution Approach 2:
The patent introduces an intermediary processing stage between the acoustic signal and the electrode stimulation that implements the MOC reflex model. This intermediary contralateral inhibition module processes signals from the opposite ear and applies dynamic inhibition to reduce noise impact before electrode stimulation, serving as a mediator that bridges the gap between basic sound perception and noise-resistant speech recognition.
2Device complexity
If constant stimulation rate is applied across all electrode channels, then device complexity is reduced, but sound localization precision deteriorates
Solution Approach 1:
The patent applies local quality by implementing channel-specific inhibition factors that are tailored to each electrode channel's frequency region. Rather than uniform processing, each channel receives customized inhibition based on its spectral characteristics and the contralateral signal in its specific frequency band, thereby improving sound localization precision without excessively increasing overall device complexity.
3Ease of manufacture
If bandwidth normalization is not applied to the MOC reflex model, then the model is simpler to implement, but channel-specific noise reduction effectiveness deteriorates
Solution Approach 1:
The patent applies parameter changes by normalizing the contralateral inhibition signal according to the bandwidth of each channel. This bandwidth normalization adjusts the inhibition parameter dynamically based on channel-specific frequency resolution, ensuring that each channel receives appropriately scaled inhibition that matches its spectral characteristics, thereby achieving precise channel-specific noise reduction.
Data Source
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AI summary
A signal processing arrangement is described for signal processing in a bilateral hearing implant system. A channel compression module develops a inhibition-adjusted band pass signal for each band pass signal using a channel-specific dynamic inhibition adjustment based on a channel-normalized medial olivocochlear reflex model that reflects bandwidth energy for a corresponding contralateral band pass signal and bandwidth energy for a selected reference contralateral band pass signal.