Cochlear Implant Threshold Estimation via Cross-Correlation
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Solution Overview
Problem
The process of calibrating cochlear implant electrode stimulation levels is time-consuming and uncomfortable for users, especially for those who cannot communicate, due to conventional methods relying on subjective and noisy near-threshold responses.
Innovation Solution
A cross-correlation threshold estimation method that sends a series of stimulation signals, calculates cross-correlation signals, and determines the threshold level by stopping when the signal exceeds a predetermined threshold, allowing for automatic and objective hearing threshold measurement without overstimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional regression-based threshold estimation is used, then threshold levels can be determined, but the measurement process becomes time-consuming and causes overstimulation discomfort
Solution Approach 1:
The patent applies preliminary action by performing cross-correlation analysis on stimulation signals before final threshold determination. The system pre-processes the electrophysiological signals using cross-correlation with reference waveforms to identify threshold levels more quickly, avoiding the time-consuming iterative regression process while maintaining accuracy.
Solution Approach 2:
The patent replaces the conventional regression-based mechanical calculation method with a signal processing approach using cross-correlation analysis. This substitution transforms the threshold estimation from a computational regression problem into a signal matching problem, enabling faster and more accurate threshold detection without overstimulation.
2Measurement precision
If supra-threshold stimulations are used for regression analysis, then threshold levels can be estimated, but the cochlea experiences overstimulation which is uncomfortable for the user
Solution Approach 1:
The patent introduces cross-correlation analysis as an intermediary method between stimulation and threshold determination. Instead of directly using supra-threshold stimulations that cause discomfort, the system uses cross-correlation of electrophysiological signals with reference waveforms as a mediator to indirectly estimate thresholds, thereby avoiding cochlear overstimulation while maintaining measurement accuracy.
Solution Approach 2:
The patent substitutes the direct supra-threshold stimulation approach with an indirect signal correlation method. By replacing the mechanical stimulation-based regression with cross-correlation analysis of neural responses, the system eliminates harmful overstimulation effects while preserving threshold estimation precision.
3Productivity
If automatic detection telemetry is implemented, then the fitting process becomes faster, but near-threshold responses are mixed with noise making detection difficult
Solution Approach 1:
The patent replaces conventional signal detection methods with cross-correlation analysis. This substitution enables the system to distinguish near-threshold electrophysiological responses from background noise by correlating them with known reference waveforms, thereby maintaining high detection accuracy in automatic telemetry mode without requiring manual intervention.
Solution Approach 2:
The patent uses cross-correlation analysis as an intermediary signal processing step between raw electrophysiological measurements and threshold determination. This intermediary process enhances the detectability of near-threshold responses by comparing them against reference waveforms, allowing automatic detection to maintain high precision while achieving fast fitting speeds.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables faster, safer, and more comfortable threshold estimations, reducing the likelihood of overstimulation and improving listening experiences by accurately determining hearing thresholds without requiring user interaction.
Implementation Method 1
receiving an electrophysiological signal for each stimulation signal from a measurement electrode attached to the head of the user
Implementation Method 2
calculating a cross-correlation signal for each of the received electrophysiological signals
Data Source
AI summary
A method of calibrating stimulation threshold levels of a cochlear implant, comprises sending a series of stimulation signals having a predetermined length in time to a selected subset of a plurality of stimulation electrodes of the cochlear implant of a user, wherein for each signal of the series of stimulation signals, the stimulation level is larger compared to the stimulation level of the previous stimulation signal; receiving an electrophysiological signal for each stimulation signal from a measurement electrode attached to the head of the user; calculating a cross-correlation signal for each of the received electrophysiological signals for each stimulation level following the first stimulation signal with respect to the first electrophysiological signal received for the first stimulation signal, determining, whether the respective cross-correlation signal exceeds a predetermined threshold level, wherein the sending of the series of stimulation signals is stopped and the stimulation level is set as the threshold stimulation level for the selected subset of stimulation electrodes, in case it is determined that the cross-correlation signal exceeds the predetermined threshold level for a first time, and outputting the level of stimulation at which the sending is stopped.