Adaptive Cut-off Frequency for Hearing Devices
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Solution Overview
Problem
Hearing devices face challenges in providing effective amplification for high-frequency sounds due to physical limitations and feedback issues, leading to unnecessary frequency compression and artifacts in output audio signals when using traditional frequency-lowering algorithms.
Innovation Solution
An adaptively adjusted cut-off frequency is implemented as a continuous function of the instantaneous input bandwidth of the audio signal, allowing for dynamic frequency compression or no compression based on the signal's characteristics, thereby optimizing the mapping of input frequencies to output frequencies without unnecessary compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency lowering algorithms are used to remap high-frequency sounds to lower frequencies, then users with hearing loss can perceive high-frequency sounds, but the available output bandwidth is unnecessarily reserved and original harmonics are significantly compressed
Solution Approach 1:
The patent applies dynamics by making the cut-off frequency adaptive rather than fixed. The cut-off frequency dynamically adjusts based on the input audio signal's characteristics (such as spectral content and bandwidth), allowing the system to optimize frequency mapping in real-time. This resolves the contradiction by preventing unnecessary bandwidth reservation and avoiding compression artifacts while maintaining hearing capability improvement.
Solution Approach 2:
The patent changes the parameter of cut-off frequency from a static value to a dynamic value that varies with input signal conditions. By adjusting the cut-off frequency based on the actual audio signal characteristics, the system avoids unnecessary frequency compression and preserves original harmonics, thereby eliminating artifacts while maintaining the benefit of making high-frequency sounds perceivable.
2Device complexity
If a fixed cut-off frequency is used in frequency lowering algorithms, then the implementation is simple, but the algorithm cannot adapt to different input audio signals and causes unnecessary compression
Solution Approach 1:
The patent transitions from a static cut-off frequency to a dynamic one that adapts to input audio signal characteristics. The system continuously monitors the input signal's spectral content and adjusts the cut-off frequency accordingly, enabling the algorithm to handle different audio scenarios optimally without excessive complexity.
Solution Approach 2:
The patent implements feedback by using the input audio signal's characteristics to determine the appropriate cut-off frequency. The system analyzes the spectral content of the input signal and uses this information to adjust the cut-off frequency, creating a closed-loop system that adapts to different audio conditions while maintaining manageable complexity.
3Quantity of substance
If frequency compression is applied to all input audio signals, then high-frequency content is compressed to fit within output bandwidth, but original harmonics are significantly compressed and sound quality deteriorates
Solution Approach 1:
The patent applies dynamics by making frequency compression conditional rather than universal. The system dynamically determines whether frequency compression is necessary based on the input signal's bandwidth and spectral characteristics. When the input signal already has limited bandwidth or when compression would harm sound quality, the system avoids compression, thereby preserving original harmonics and maintaining high sound quality while still optimizing bandwidth utilization when needed.
Data Source
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AI summary
A hearing device (100) includes a memory (102) storing instructions and a processor (104) communicatively coupled to the memory (102). The processor (104) is configured to execute the instructions to receive (202) an input audio signal having a range of input frequencies, adaptively adjust (206) a cut-off frequency for the input audio signal such that a value of the cut-off frequency varies between a predefined minimum cut-off frequency value and a predefined maximum cut-off frequency value as a continuous function of the input audio signal, and generate (210) an output audio signal by mapping the range of input frequencies to a range of output frequencies determined based on the adaptively adjusted cut-off frequency.