Cochlear Implant Stimulation Patterns for Neural Phase-Locking
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Solution Overview
Problem
Current auditory implant systems, such as cochlear implants, face limitations in extending the range of phase-locking neural responses to stimulation pulses, which can affect hearing directionality and speech understanding, particularly at higher stimulation rates.
Innovation Solution
The system generates electrode stimulation signals using transition event and non-transition stimulation patterns, with transition event patterns featuring sequential biphasic pulses with short inter-pulse intervals, and non-transition patterns consisting of single biphasic pulses, to improve ITD perception and maintain or enhance speech perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stimulation patterns with longer inter-pulse intervals are used, then neural response reliability is maintained, but the range of phase-locking neural responses cannot be extended to higher stimulation rates
Solution Approach 1:
The system dynamically adjusts the inter-pulse interval based on the stimulation rate. At higher stimulation rates, shorter inter-pulse intervals are used to extend phase-locking range, while at lower rates, longer intervals maintain reliability. This dynamic adaptation allows the system to optimize performance across different operating conditions.
Solution Approach 2:
The patent changes the temporal parameter (inter-pulse interval) of the stimulation signal to extend the range of phase-locking neural responses. By using shorter inter-pulse intervals in transition event patterns, the system enables neural phase-locking at higher stimulation rates, thereby expanding the operational range without sacrificing reliability through the use of different patterns.
2Productivity
If higher stimulation rates are used, then speech perception may be improved, but hearing directionality and ITD perception deteriorate
Solution Approach 1:
The system uses periodic transition event patterns with short inter-pulse intervals to create distinct temporal markers that enhance ITD perception. These periodic patterns provide reliable timing cues for interaural time difference detection, allowing the system to maintain directionality perception even at higher overall stimulation rates used for speech perception.
3Adaptability or versatility
If short inter-pulse interval patterns are used continuously, then phase-locking range is extended, but speech perception may be compromised
Solution Approach 1:
The system segments the stimulation signal into different patterns: transition event patterns with short inter-pulse intervals for extending phase-locking range, and non-transition patterns with longer intervals for maintaining speech perception. By selectively applying different patterns to different signal components, the system achieves both extended phase-locking and good speech perception.
Solution Approach 2:
Different inter-pulse interval characteristics are applied locally to different portions of the stimulation signal. Transition event patterns use short intervals locally where phase-locking is needed, while non-transition patterns use longer intervals where speech perception is prioritized. This local differentiation allows simultaneous optimization of both functions.
Data Source
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AI summary
Arrangements are described for generating electrode stimulation signals for an implanted electrode array having multiple stimulation contacts. An audio input preprocessor receives an input audio signal and generates band pass signals that represent associated bands of audio frequencies. A band pass signal analyzer analyzes each band pass signal to detect when one of the band pass signal components reaches a defined transition event state. A stimulation signal generator generates a set of electrode stimulation signals for the stimulation contacts from the band pass signals such that the electrode stimulation signals to a given stimulation contact: i. use a transition event stimulation pattern whenever a transition event is detected in a band pass signal associated with the given stimulation contact, and ii. use a different non-transition stimulation pattern after the transition event stimulation pattern until a next subsequent transition event is detected.