Hearing Aid Signal Conditioning for A/D Distortion and Noise
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Solution Overview
Problem
Hearing aid devices face challenges in miniaturization due to A/D converter limitations, leading to signal distortions and poor signal-to-noise ratios, particularly when handling a wide hearing spectrum, resulting in undesirable acoustic impressions.
Innovation Solution
A method involving a preamplifier that amplifies or attenuates analog signals in a broadband manner, followed by A/D conversion and digital signal processing, with a noise suppression unit that adjusts based on signal levels to improve signal-to-noise ratios and reduce noise artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the hearing aid device uses digital technology with A/D converter for miniaturization, then device size is reduced, but signal distortion and poor signal-to-noise ratio occur
Solution Approach 1:
The patent applies preliminary action by performing analog signal processing (preamplification, filtering, compression) before A/D conversion. This prepares the signal in advance to prevent overdrive and distortion during digital processing, thereby maintaining signal quality while enabling device miniaturization through digital technology.
Solution Approach 2:
The patent introduces an analog preamplifier and signal conditioning circuitry as intermediary components between the microphone and A/D converter. These intermediary analog processing stages prepare the signal appropriately before digital conversion, resolving the contradiction between digital miniaturization and signal quality preservation.
2Reliability
If the preamplifier gain is increased to improve signal-to-noise ratio, then noise is reduced, but signal distortion occurs when strong input signals are present
Solution Approach 1:
The patent applies dynamics by implementing automatic gain control (AGC) and compression algorithms that dynamically adjust the preamplifier gain based on input signal levels. When strong signals are detected, gain is reduced to prevent distortion; when weak signals are present, gain is increased to improve signal-to-noise ratio, thereby resolving the contradiction between noise reduction and distortion prevention.
Solution Approach 2:
The patent changes the gain parameter of the preamplifier dynamically based on input signal characteristics. By adjusting this critical parameter adaptively, the system maintains optimal signal-to-noise ratio for weak signals while preventing overdrive and distortion for strong signals, thus resolving the contradiction.
3Object-affected harmful factors
If the preamplifier gain is decreased to prevent signal overdrive, then distortion is reduced, but noise from A/D converter is amplified strongly
Solution Approach 1:
The patent replaces the purely analog gain control mechanism with a hybrid system that uses digital signal processing algorithms to manage noise. Instead of relying solely on analog preamplifier gain settings, digital noise suppression and signal enhancement techniques are applied after A/D conversion to compensate for the reduced analog gain, thereby preventing distortion while maintaining acceptable signal-to-noise ratio.
Data Source
AI summary
A method for operating a hearing device, in particular a hearing aid device, in which a first analog signal is provided. A second analog signal is generated by a preamplifier based on the first analog signal, and a first digital signal is generated by an A/D converter based on the second analog signal. A second digital signal is generated by an amplifier based on the first digital signal, and a third digital signal, in which a noise is reduced in comparison with the second digital signal, is generated by a noise suppression unit based on a second digital signal. The preamplifier, amplifier, and noise suppression unit are set using a value characterizing the first digital signal.