Hearing Aid Gain Control via Dynamic Release Times

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Solution Overview

Problem

Existing hearing aid systems face challenges in controlling gain transfer functions, particularly in varying sound environments, leading to issues such as prolonged inability to hear low sound levels after exposure to high sound events and loss of speech signals due to long release times and noise suppression.

Innovation Solution

A hearing aid system with parallel signal paths for determining specific attack and release times, utilizing separate filterbanks for maximum level, squelch level, and compression level detection to generate control signals, ensuring optimal gain adjustment across different sound situations by employing short and long attack and release times based on detected thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If long release time is used for noise suppression and gain control, then noise suppression is improved, but the user cannot hear low sound levels for a prolonged period after high sound events

Engineering Contradiction:

Improvenoise suppressionVSAvoidrecovery time for low sound detection

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent implements dynamic adjustment of release time based on input signal characteristics. The release time is set to a first value (shorter) when input signal levels are high, and a second value (longer) when input signal levels are low. This dynamic parameter adjustment resolves the contradiction by adapting the noise suppression aggressiveness to the current acoustic environment, preventing prolonged mute periods after loud events while maintaining effective noise suppression during quiet periods.

Inventive Principle:

Principle #15Dynamics

2Loss of information

If long attack time is used for noise suppressor, then speech signals are preserved, but background noise is not effectively suppressed

Engineering Contradiction:

Improvespeech signal preservationVSAvoidbackground noise suppression

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The attack time parameter is dynamically adjusted based on the detected input signal level and characteristics. When speech signals are detected, a shorter attack time is applied to quickly suppress background noise. When only background noise is present or signal levels are very low, a longer attack time is used to avoid suppressing speech. This dynamic adaptation resolves the contradiction between speech preservation and noise suppression effectiveness.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If single gain control mechanism is used, then device complexity is reduced, but adaptability to varying sound environments deteriorates

Engineering Contradiction:

Improvegain control mechanismVSAvoidperformance in varying sound environments

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the gain control mechanism into multiple parallel signal paths: a first signal path for maximum output power determination with its own attack and release times, and a second signal path for compression level detection with different timing characteristics. Each path processes the input signal independently and generates control signals that are combined to drive the gain control. This segmentation allows the system to adapt to different sound environments effectively while maintaining manageable complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically selects and adjusts different gain control parameters based on the current acoustic environment. The controller means adapts attack and release times, compression ratios, and threshold levels in real-time based on signal analysis from multiple detector means. This dynamic adaptability resolves the contradiction by enabling the single gain control mechanism to effectively handle varying sound environments through parameter modulation rather than structural complexity.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The system provides precise and adaptive gain control, preventing distortion and unnecessary amplification, ensuring the user receives optimal sound processing across a wide range of environments, maintaining clear speech and minimizing noise interference.

Implementation Method 1

a microphone adapted to convert a sound pressure to an input signal

Methodology Applied

Scientific EffectAcoustic transduction:

Implementation Method 2

a speaker adapted to convert an output signal to a processed sound pressure

Methodology Applied

Scientific EffectElectroacoustic transduction:

Data Source

PatentUS8014550B2System for controlling a transfer function of a hearing aid

Publication Date: 2011.09.06 OTICON

AI summary

This invention relates to a system (100) for controlling gain function of a hearing aid. The system (100) comprises a microphone (102) converting a sound pressure to an input signal, a speaker (112) converting an output signal to a processed sound pressure, and a signal processing means (106) interconnecting the microphone (102) and the speaker (112) and processing the input signal to the output signal according to a control signal. The system (100) further comprises a signal analysis means (108) connecting to the microphone (102) and to the signal processing means (106) and comprising a controller means (124) generating the control signal based on detector means (128, 130, 120) responses to the input signal.