Hearing Aid Signal Processing Path Group Delay Compensation

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Solution Overview

Problem

Hearing devices with uncontrolled signal transmission paths cause disturbances in sound perception due to differences in group delays, leading to unnatural echoing effects and reduced noise cancellation performance in 'open' fitted devices.

Innovation Solution

A second controlled signal processing path is introduced to compensate for uncontrolled signal transmission by establishing a shorter group delay, exploiting parts of the first CSPP's processing, including electrical-to-mechanical conversion, to minimize the difference in group delays between the two paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a hearing device is applied with an open fitted configuration to reduce occlusion sensation, then the sensation of occlusion is reduced, but uncontrolled signal transmission through vents and gaps causes disturbances and unnatural echoing effects

Engineering Contradiction:

Improvesensation of occlusionVSAvoiddisturbances in sound perception

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a second controlled signal processing path that acts as an intermediary to capture and process the uncontrolled signals transmitted through vents and gaps. By routing these signals through a controlled path with adjustable parameters, the system can compensate for the uncontrolled transmission and eliminate disturbing echoes while preserving the open fitted configuration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent dynamically adjusts parameters of the second controlled signal processing path, including gain factors and delay times, to match the characteristics of uncontrolled signal transmission. By changing these parameters adaptively, the system compensates for variations in vent transmission and maintains natural sound perception without occlusion effects.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If signal processing is performed along a controlled path to improve sound perception, then sound quality is improved, but the group delay becomes significantly larger than natural transmission delay causing unnatural echoing effects

Engineering Contradiction:

Improvesound perception qualityVSAvoidgroup delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent segments the signal processing into two separate controlled paths: a first path for primary sound processing and a second path for compensating uncontrolled transmission. By dividing the processing functions, the system can apply different delay characteristics to each path, minimizing overall group delay while maintaining sound quality through coordinated processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary delay adjustment in the second controlled signal processing path to pre-compensate for the time difference between controlled and uncontrolled signal transmission. By anticipating and correcting the delay mismatch before signal combination, the system eliminates echoing effects while preserving the benefits of controlled signal processing.

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If noise cancellation is implemented in open fitted hearing devices, then noise reduction is achieved, but uncontrolled signal transmission through vents reduces noise cancellation performance

Engineering Contradiction:

ImprovenoiseVSAvoidnoise cancellation performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the second controlled signal processing path continuously monitors and processes signals transmitted through vents and gaps. By feeding back compensatory signals that counteract uncontrolled transmission, the system maintains effective noise cancellation performance despite the presence of open fitted configuration and vent transmission.

Inventive Principle:

Principle #23Feedback

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

This approach effectively reduces disturbances from uncontrolled signal transmission, improving sound perception by ensuring accurate signal compensation, with group delay differences of 40 μsec or less, and further enhancing noise cancellation performance.

Implementation Method 1

The CSPP is established by the input acoustical-to-electrical converter arrangement of the device and the subsequent signal processing

Methodology Applied

Scientific EffectAcoustical-to-electrical conversion:

Implementation Method 2

subsequent signal processing up to and including output electrical-to-mechanical conversion at a respective output-converter arrangement of the device

Methodology Applied

Scientific EffectElectrical-to-mechanical conversion:

Implementation Method 3

The UCSTP comprises bone acoustical transmission, acoustical transmission along and through the shell of the device

Methodology Applied

Scientific EffectBone acoustical transmission:

Data Source

PatentUS8867766B2Method for producing a signal which is audible by an individual

Publication Date: 2014.10.21 SONOVA AG

AI summary

Audible signals (m2) which are transmitted via an uncontrolled transmission path (11) to an individual's ear wearing the control signal processing path (1) of a hearing device are compensated by audible signals (m3) which are produced by an additional controlled signal processing path (20). Signal processing parts are commonly exploited (25b, 25d, 7/27) by both controlled signal processing paths (1, 20).