Dynamic Stimulation Channel Selection in Cochlear Implants
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Solution Overview
Problem
Current cochlear implant systems face limitations in effectively coding electrical stimulation pulses, particularly in representing temporal properties and speech onsets, leading to spectral clustering and reduced availability of electrode channels for coding important sound features.
Innovation Solution
A signal processing arrangement that utilizes a signal filter bank to transform input sound signals into band pass signals, with an envelope processing module calculating dynamic properties and a channel selection module selecting electrode channels based on these properties to generate electrode stimulation signals, enhancing temporal representation and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a small number of electrode channels are used with broad frequency bands, then the device complexity is reduced, but the temporal representation and speech onset detection capability deteriorates
Solution Approach 1:
The patent applies dynamics by making the electrode channel selection adaptive and time-varying. Instead of using a fixed number of channels with broad frequency bands, the system dynamically selects from a larger pool of electrode channels based on real-time signal characteristics. This allows the system to optimize temporal representation precision by activating more channels when needed (e.g., during speech onsets) while maintaining manageable complexity through selective activation rather than always using maximum channels.
2Device complexity
If stimulation pulses are applied at constant rate across all electrode channels, then the device complexity is reduced, but the loss of information about temporal properties and speech onsets increases
Solution Approach 1:
The system dynamically adjusts the stimulation rate for different electrode channels based on the input signal characteristics. During speech onsets or when temporal information is critical, the system increases the stimulation rate for relevant channels to capture temporal properties accurately. During steady-state sounds, the system can reduce the stimulation rate to minimize complexity. This dynamic rate adjustment allows the system to recover temporal information that would otherwise be lost in constant-rate stimulation.
Solution Approach 2:
The patent changes the stimulation rate parameter from a fixed constant value to a variable parameter that adapts to signal conditions. By modifying the stimulation rate based on detected speech onsets, frequency content, and signal envelope characteristics, the system preserves temporal information while managing complexity through parameter modulation rather than always operating at maximum complexity.
3Measurement precision
If channel-specific stimulation rates are used, then the temporal representation is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different stimulation rates to different electrode channels based on their specific characteristics and the current signal analysis. Rather than using a uniform rate for all channels, the system determines optimal local stimulation rates for each channel based on factors such as center frequency, bandwidth, and current signal envelope properties. This localized optimization improves temporal representation precision for each channel while managing overall complexity through efficient, channel-specific processing rather than uniform high-rate processing of all channels.
Data Source
AI summary
A signal processing arrangement generates electrode stimulation signals to stimulation contacts in a cochlear implant electrode array. A signal filter bank transforms an input sound signal into band pass signals, which each represent an associated frequency band of audio frequencies. An envelope processing module processes the band pass signals in a sequence of sampling time frames, wherein for each time frame, the processing includes calculating for each band pass signal at least one signal envelope dynamic property that is changing during the time frame. A channel selection module selects one or more of the band pass signals for each time frame based on the dynamic properties to produce the electrode stimulation signals to the stimulation contacts.