Binaural Stimulation Signals with Phase Jitter for Cochlear Implants
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Solution Overview
Problem
Conventional cochlear implants (CIs) fail to effectively utilize fine structure information for sound localization and speech understanding in noise, due to binaural adaptation, which limits interaural time difference (ITD) sensitivity, especially at higher pulse rates.
Innovation Solution
The introduction of artificial phase jitter into binaural stimulation signals reduces periodic characteristics while preserving ITD information, enhancing sound localization and speech understanding by synchronizing phase jitter between left and right signals to avoid binaural adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fine structure information is used in conventional CIs with periodic pulsatile carrier signals, then ITD information is provided, but binaural adaptation occurs which limits ITD sensitivity especially at higher pulse rates
Solution Approach 1:
The patent applies dynamics by making the carrier signal frequency variable rather than fixed. The system dynamically adjusts the instantaneous frequency of the pulsatile carrier signal based on the instantaneous frequency of the acoustic signal, creating a non-periodic, time-varying stimulation pattern that prevents binaural adaptation while preserving ITD information
Solution Approach 2:
The patent changes the parameter of carrier signal frequency from a fixed periodic value to a time-varying parameter that follows the acoustic signal's instantaneous frequency. This parameter change transforms the stimulation from a periodic pattern that causes adaptation to a dynamic pattern that maintains sensitivity
2Ease of manufacture
If the frequency and phase of the pulsatile carrier signal are dictated by the speech processor rather than the fine structure, then the system is simpler to implement, but fine structure ITD information is not utilized
Solution Approach 1:
The patent applies preliminary action by pre-processing the acoustic signal to extract instantaneous frequency information before generating the carrier signal. The fine structure information is analyzed in advance to determine the time-varying frequency pattern that will modulate the carrier, ensuring ITD information is captured without complex real-time processing
Solution Approach 2:
The patent introduces an intermediary mechanism where the instantaneous frequency of the acoustic signal acts as a modulating parameter for the carrier signal. This intermediary approach allows the system to transfer fine structure ITD information to the electrical stimulation without requiring direct complex processing of the carrier signal itself
Data Source
AI summary
The present invention discloses of binaural stimulation in a neural auditory prosthesis. Binaural acoustic signals are generated that represent sound associated with a user's left and right ears respectively. Based on the binaural acoustic signals, corresponding binaural stimulation signals are generated for electrical stimulation of auditory nerve tissue of the user, wherein the binaural stimulation signals each include a fine structure component with periodic characteristics and interaural time difference (ITD) information. A phase jitter component is added to the binaural stimulation signals to reduce the periodic characteristics of the fine structure component while preserving the interaural time difference (ITD) information.