Cochlear Implant Noise Reduction via Electrode-Nerve Model
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Solution Overview
Problem
Conventional noise reduction methods in cochlear implant systems often result in distortion of desired speech signals, especially at low signal-to-noise ratios and in non-stationary noise environments, due to inadequate consideration of the electrode-nerve interface effects.
Innovation Solution
The system employs an electrode-nerve-interface model to estimate noise reduction based on individual or average electrical measurements, accounting for the hearing perception impact of stimulation channels, thereby optimizing noise reduction without distorting the desired speech signal. This model considers noise spread from neighboring channels and determines a signal-to-mask ratio to adjust noise reduction gain parameters, ensuring that noise is reduced below the perception threshold to avoid distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise reduction methods are applied to attenuate noise in cochlear implant systems, then noise level is reduced, but distortion of desired speech signals occurs
Solution Approach 1:
The patent applies different processing approaches to different frequency channels based on their individual signal-to-noise ratios. Each analysis channel is evaluated separately, and noise reduction is applied selectively only to channels where the noise floor exceeds a determined threshold, preserving speech channels while attenuating noise channels. This localized approach prevents distortion of desired speech signals while reducing noise in affected channels.
Solution Approach 2:
The patent applies noise reduction selectively rather than uniformly across all channels. By determining a noise floor threshold for each channel and applying attenuation only where necessary (when noise exceeds the threshold), the system achieves partial action - reducing noise only in the specific channels and regions where it is problematic, thereby avoiding unnecessary distortion of speech signals in channels where noise is not the dominant issue.
2Object-affected harmful factors
If noise reduction is applied to attenuate noise-only channels, then noise level is reduced, but speech understanding in noisy environments remains impaired
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the noise floor in each analysis channel, compares it against a determined threshold, and dynamically adjusts the noise reduction gain accordingly. This closed-loop approach ensures that noise reduction is applied adaptively based on real-time conditions, maintaining speech understanding capability while reducing noise levels in challenging listening environments.
Solution Approach 2:
The patent changes the parameter of noise reduction gain dynamically based on the determined noise floor threshold for each channel. By adjusting this parameter adaptively rather than using fixed attenuation values, the system optimizes the balance between noise reduction and speech preservation, improving speech understanding in noisy environments without causing excessive distortion.
3Quantity of substance
If channel-specific gain is applied to maintain speech level, then speech signal level is maintained, but noise in other channels spreads to the desired channel
Solution Approach 1:
The patent introduces an intermediary evaluation step - determining the noise floor threshold for each channel - between the gain application and noise reduction processes. This intermediary assessment allows the system to identify which channels are primarily noise-dominated versus speech-dominated, enabling selective noise reduction that prevents noise spread while preserving speech signals. The threshold determination acts as a mediator that guides the noise reduction process to avoid affecting speech channels.
Data Source
AI summary
A system includes a cochlear implant electrode arrangement comprising a plurality of stimulation channels; means for dividing an audio signal into a plurality of analysis channels; means for establishing an electrode-nerve-interface model of hearing stimulation via the cochlear implant electrode arrangement; means for determining a signal level value and a noise level value for each analysis channel by analyzing the respective frequency domain signal; means for determining a noise reduction gain parameter for at least some of the analysis channels as a function of the signal level value and the noise level value of the respective analysis channel; means for applying noise reduction to the frequency domain signal according to the noise reduction gain parameters to generate a noise reduced frequency domain signal; and means for generating a stimulation signal for each of the stimulation channels according to the noise reduced frequency domain signal.