Adjustable Microphone Directivity for Speech Intelligibility Assessment

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Solution Overview

Problem

Hearing impaired individuals face challenges in distinguishing between competing sound sources in noisy environments due to low signal-to-noise ratio, limiting their ability to understand speech, as existing hearing aid technologies lack effective methods to assess speech intelligibility without access to a clean speech signal.

Innovation Solution

A method using an adjustable microphone arrangement to generate 'pseudo' clean speech signals by controlling directivity patterns, allowing for the estimation of objective perceptual quantities like speech intelligibility through comparison of noisy speech segments recorded with different directivity indices, enabling adaptive signal processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If advanced speech processing algorithms are applied to enhance speech intelligibility, then speech understanding improves in noisy environments, but sound artifacts are introduced and processing complexity increases

Engineering Contradiction:

Improvespeech intelligibilityVSAvoidsound artifacts

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The system performs preliminary assessment of the acoustic environment and speech signal quality before applying advanced processing algorithms. By evaluating objective perceptual quantities and comparing noisy speech segments with different directivity patterns, the system determines in advance whether advanced processing is actually needed, thereby avoiding unnecessary artifact introduction while maintaining speech intelligibility when required

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes processing parameters based on the assessed listening conditions. By adjusting the degree of noise reduction, beamforming strength, and other processing parameters according to the measured speech intelligibility and noise level, the system optimizes the balance between enhancing speech understanding and minimizing artifact introduction

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If advanced speech processing algorithms are applied, then speech intelligibility improves, but device complexity increases

Engineering Contradiction:

Improvespeech intelligibilityVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies processing algorithms selectively and partially based on the assessed needs. Rather than always applying full advanced processing, the system adjusts the degree and type of processing to match the actual listening conditions, reducing complexity when simple processing suffices while maintaining effectiveness when needed

Inventive Principle:

Principle #16Partial or excessive action

3Measurement precision

If directivity patterns are adjusted to improve speech signal quality, then speech intelligibility improves, but the ability to capture ambient sound decreases

Engineering Contradiction:

Improvespeech intelligibilityVSAvoidambient sound information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The system dynamically adjusts the directivity pattern of the microphone arrangement based on the assessed listening conditions and speech intelligibility requirements. By switching between different directivity patterns (e.g., omnidirectional, cardioid, supercardioid) and adjusting beamforming parameters in real-time, the system optimizes the balance between capturing speech signals and preserving ambient sound information according to the specific situation

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

This approach allows for accurate estimation of speech intelligibility and quality measures, enabling adaptive signal processing to improve hearing aid performance in noisy conditions without introducing unnecessary artifacts.

Implementation Method 1

controlling the adjustable microphone arrangement to produce first and second predetermined directivity patterns exhibiting first and second directivity indexes, respectively

Methodology Applied

Scientific EffectDirectivity pattern: Acoustics

Data Source

PatentUS10397711B2Method of determining objective perceptual quantities of noisy speech signals

Publication Date: 2019.08.27 GN HEARING AS

AI summary

The present disclosure relates in a first aspect to a method of determining an objective perceptual quantity of a noisy speech signal using directional sound information. The method comprises steps of applying a noisy speech signal comprising a mixture of target speech and interfering noise to a first hearing instrument with an adjustable microphone arrangement and controlling the adjustable microphone arrangement to produce first and second directivity patterns exhibiting first and second directivity indexes, respectively, wherein said second directivity index is smaller than the first directivity index at one or more reference frequencies. First and second noisy speech segments are recorded from the adjustable microphone arrangement using the first and second directivity patterns, respectively, and at least one value of the objective perceptual quantity of the noisy speech signal is determined by comparing the first noisy speech segment and the second noisy speech segment.