Variable Pulse Rate Stimulation Timing for Cochlear Implants
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Solution Overview
Problem
Conventional cochlear implants and auditory brain stimulators face challenges with variable latency in signal processing, leading to loss of phase difference information and high power consumption due to fixed pulse rates, which results in poor coding of interaural timing cues and reduced battery life.
Innovation Solution
The system determines stimulation timing by filtering received signals into band-pass channels, processing envelopes to select pulse times based on peak phases, and combines these with amplitude information from a separate spectral path to adjust pulse rates within a perceptually relevant range, maintaining phase differences and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a high fixed pulse rate is used for stimulation, then the perceived sound becomes more natural and less robotic, but power consumption increases and battery life decreases
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed pulse rate to a variable pulse rate that adapts to the signal characteristics. The system dynamically adjusts the pulse rate based on the instantaneous frequency content of the audio signal, allowing the pulse rate to vary within a range rather than remaining constant. This resolves the contradiction by enabling natural sound perception when high pulse rates are needed while reducing power consumption when lower rates suffice.
Solution Approach 2:
The patent implements parameter changes by modifying the pulse rate parameter based on signal analysis. The system changes the pulse rate parameter dynamically according to the frequency content and temporal characteristics of the input signal, rather than maintaining a fixed parameter value. This allows optimization of both naturalness and power efficiency through adaptive parameter adjustment.
2Adaptability or versatility
If variable latency is used in signal processing, then processing flexibility increases, but phase difference information is lost and interaural timing cues are poorly coded
Solution Approach 1:
The patent applies preliminary action by performing phase alignment and timing compensation before the final stimulation output. The system pre-processes the binaural signals to preserve interaural timing cues and phase relationships, ensuring that critical temporal information is maintained before any variable latency effects occur. This allows flexible processing while preventing information loss.
Solution Approach 2:
The patent implements feedback mechanisms to monitor and correct timing deviations. The system continuously analyzes the processed signals to detect phase differences and timing errors, then applies corrective adjustments to maintain accurate interaural timing cues. This feedback loop ensures that adaptability does not come at the cost of information loss.
Data Source
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AI summary
Methods and systems are disclosed for determining the timing of stimulation applied using a medical device. In embodiments, the medical device filters a received signal to obtain a plurality of band-pass filtered signals, each corresponding to one or more stimulation channels. The medical device then determines the envelopes of these band-pass filtered signals. Next, the medical device determines the stimulation timing (i.e., the pulse times) for the corresponding stimulation channel based on the timing of a particular phase (e.g., a peak, a minimum, etc.) of the envelope. A pulse amplitude for the stimulation channel may then be determined, and stimulation applied using the determined amplitude and pulse time.