Cochlear Stimulation System TFS Parameter Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cochlear implant systems struggle to effectively encode the Temporal Fine Structure (TFS) parameter of acoustic signals, leading to poor performance in noisy environments and limited music enjoyment, as they primarily focus on the slow-varying acoustic temporal envelope, discarding important TFS information that aids in pitch perception and spatial hearing.
Innovation Solution
A cochlear stimulation system that determines the TFS parameter from the full frequency range of an incoming acoustic signal using a transducer, window analyzer, and signal processor, which performs time-to-frequency transformation and energy level difference analysis to accurately extract fundamental frequencies and harmonics, avoiding the limitations of filter-bank methods by processing the entire frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filter-bank method is used to extract TFS parameter, then frequency band segmentation is achieved, but spectral resolution and computational complexity are limited
Solution Approach 1:
The patent replaces the mechanical filter-bank system with a mathematical approach using FFT (Fast Fourier Transform) and window function analysis. Instead of using physical or digital filters to divide frequency bands, the system uses spectral analysis through FFT followed by window function-based energy difference calculations to extract TFS parameters, significantly reducing computational complexity while maintaining or improving spectral resolution
Solution Approach 2:
The patent changes the fundamental parameter for TFS extraction from filter bandwidth and center frequency to spectral energy differences at specific frequency offsets from the peak frequency. By using the formula ΔE(f₀±Δf) = E(f₀±Δf) - E(f₀), the system extracts TFS information directly from the spectral envelope shape without being constrained by filter bank design parameters
2Measurement precision
If number of filter bands is increased to improve frequency resolution, then more spectral components can be resolved, but system latency and computational load increase
Solution Approach 1:
The patent substitutes the iterative filter-tuning process with a direct FFT-based spectral analysis. The system performs a single FFT transformation followed by peak detection and window function evaluation at predetermined frequency offsets, eliminating the need for multiple filter adjustments and reducing processing time while achieving the same frequency resolution
3Measurement precision
If filter bandwidth is reduced to improve spectral selectivity, then better separation of adjacent components is achieved, but more filters are needed increasing complexity
Solution Approach 1:
The patent replaces the filter-based spectral selection mechanism with a mathematical window function approach. After identifying the peak frequency through FFT, the system evaluates energy differences at predetermined frequency offsets using a window function w(Δf), providing spectral selectivity without requiring multiple filters or complex filter banks
4Reliability
If conventional CI coding strategies encode only temporal envelope, then speech understanding in quiet is improved, but performance in noisy environments and music perception deteriorates
Solution Approach 1:
The patent merges temporal envelope information with temporal fine structure information in a unified coding strategy. By extracting both ENV (from spectral envelope) and TFS (from spectral fine structure using the window function method), the system provides comprehensive auditory information that maintains speech understanding in quiet conditions while also improving performance in noisy environments and for music perception
Solution Approach 2:
The patent introduces TFS parameters as an intermediary between the acoustic signal and the neural stimulation pattern. The extracted TFS information (frequency offsets and energy differences) serves as a mediator that preserves fine temporal structure information, enabling the system to convey pitch, timbre, and spatial cues that enhance adaptability to different listening conditions
Data Source
AI summary
A cochlear stimulation system for determining a Temporal Fine Structure (TFS) parameter of a spectral component of an incoming acoustic signal is provided. The system comprises a transducer receiving an incoming acoustic signal, and wherein a sampled audio signal of length N samples is provided based on the incoming acoustic signal, a storing unit including a plurality of window frequency differences and/or a plurality of window energy level differences. The system further comprises a signal processor for estimating the TFS parameter of the full frequency range of the sampled audio signal by locating a main spectrum sample of the plurality of spectrum samples having a maximum energy level within a range of frequencies centered around the main spectrum sample, and determining the TFS parameter based on the energy level difference for one or more of the spectrum samples of the group of spectrum samples and the window function.