Cochlear Implant Tone Processor Enhancing Pitch Perception
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Solution Overview
Problem
Cochlear implants struggle to effectively process voice and musical pitch information, particularly in noisy environments, due to limitations in existing sound processing strategies that fail to accurately convey pitch cues, which are crucial for speech perception and tonal languages.
Innovation Solution
A system that converts sound signals into electrical signals, processes them into frequency channels, estimates fundamental frequency and harmonic information, and modulates channel outputs based on this information to enhance pitch perception, using a combination of band pass filters, envelope detectors, and periodic probability estimation to adaptively modulate and combine channel signals for improved stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voice pitch information is coded by electrical stimulation rate, then pitch perception is achieved, but performance deteriorates rapidly in noisy environments
Solution Approach 1:
The patent dynamically adapts the coding strategy based on signal characteristics. It switches between rate coding and envelope modulation depending on whether the signal is speech-like or tonal, and adjusts modulation depth based on signal-to-noise ratio estimates, making the system responsive to changing acoustic conditions
Solution Approach 2:
The patent changes key parameters including modulation depth (varying from shallow to deep modulation), stimulation rate, and modulation frequency based on the detected signal type and noise level. This allows optimization of pitch coding for different listening conditions
2Loss of information
If voice pitch information is coded by amplitude modulation in the envelope, then pitch cues are provided, but salience and accuracy are poor for some signals
Solution Approach 1:
The patent applies different modulation depths to different frequency channels based on their spectral content and importance. High-frequency channels receive different treatment than low-frequency channels, with modulation depth adjusted according to the specific channel's characteristics and the overall signal type
Solution Approach 2:
The system dynamically adjusts modulation depth based on signal characteristics and noise level. For speech-like signals, shallow modulation is used to preserve temporal fine structure, while for tonal signals or in noisy conditions, deeper modulation enhances pitch salience
3Ease of operation
If existing sound processing strategies are used, then open-set speech discrimination is achieved, but voice pitch and melody perception are poor
Solution Approach 1:
The patent merges multiple coding approaches within a unified framework. It combines rate coding, envelope modulation, and spectral peak tracking, allowing the system to leverage the strengths of each method depending on the signal being processed
Solution Approach 2:
The patent creates a multi-functional sound processing strategy that can handle multiple types of signals (speech, music, tonal languages) with a single integrated system. The adaptive nature allows one system to perform multiple functions that previously required separate processing approaches
Data Source
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AI summary
A method for processing sound signals comprising: converting a sound signal into an electrical signal; determining information from the electrical signal relating to a fundamental frequency; and filtering the electrical signal into a plurality of frequency channels: wherein for each of the one or more frequency channels, the method comprises: deriving a slow-varying channel envelope signal; modulating the slow-varying envelope signal in accordance with the fundamental frequency; determining information relating to the time-varying frequency of partials in the channel signal; determining a harmonic-relationship between the fundamental frequency and the frequency partials in the channel signal, and mixing the modulated channel envelope signal with the channel signal in accordance with the determined harmonic-relationship.