Hearing Device Signal Limiting Before Synthesis for Stable Output
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Solution Overview
Problem
Existing hearing devices face issues with high input signal levels leading to unpleasant output signals, high energy consumption, and potential malfunctions due to voltage dips, especially when dealing with transient noises.
Innovation Solution
A hearing device with a signal processing unit that includes a filter bank to divide input signals into frequency bands, a level detector upstream of the synthesis unit to determine signal levels, and a level limiter downstream to limit the output signal based on these levels, ensuring precise and broadband signal limiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If signal processing is performed with high input signal levels, then the signal processing can handle loud sound sources, but the output signal level becomes too high causing unpleasant perception and potential malfunctions
Solution Approach 1:
The level detector determines the signal level of each frequency component before synthesis, allowing preliminary identification of potentially problematic high-level signals. This enables the system to prepare appropriate limiting actions in advance, preventing output distortion before it occurs.
Solution Approach 2:
Instead of applying uniform signal processing to all frequency bands, the invention applies frequency-specific amplification factors and individual level limiting to each frequency component. This localised approach allows precise control over which frequency components are limited, maintaining audio quality while preventing harmful output levels.
2Adaptability or versatility
If high input signal levels are processed, then loud sound sources can be handled, but energy consumption and current peaks increase
Solution Approach 1:
The system dynamically adjusts amplification factors for each frequency band based on the detected signal level. When high input levels are detected, the amplification factors are reduced accordingly, preventing excessive energy consumption while maintaining the ability to handle loud sound sources when appropriate.
3Adaptability or versatility
If high input signal levels are processed, then loud sound sources can be handled, but voltage dips occur causing malfunctions
Solution Approach 1:
By detecting signal levels before synthesis and limiting high-level components in advance, the system prevents the generation of high current peaks that would otherwise cause voltage dips and power supply instability.
4Speed
If level detection is performed before filter bank, then transient detection can be done early, but signal level determination is less precise
Solution Approach 1:
The level detector operates in parallel with the filter bank processing, determining signal levels of frequency components after filtering but before synthesis. This timing allows the system to benefit from both the frequency-specific precision of post-filter detection and the speed of early level determination for transient signals.
Data Source
AI summary
A hearing device includes an input converter, a signal processing unit and an output converter. The signal processing unit has a filter bank for dividing an input signal into a plurality of signal components in different frequency bands, a processing unit for processing the signal components, and a synthesis unit for synthesizing the processed signal components into an output signal. In order to limit the level of an output signal, a level detector is disposed upstream of the synthesis unit and is configured to determine a signal level based on the signal components and to output a level signal. A level limiter, at which the level signal is transmitted, is disposed downstream of the synthesis unit and is configured to limit the level of the output signal in dependence on the level signal. A method for signal processing in a hearing device is also provided.