Dynamic Speech Equalization for Loudspeaker Intelligibility

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Solution Overview

Problem

Existing loudspeaker systems, particularly in applications like speakerphones and teleconferencing, face challenges with suboptimal frequency content in incoming speech signals due to poor microphone design, noisy environments, and bandwidth limitations, leading to reduced listening comfort and speech intelligibility.

Innovation Solution

A method and system that dynamically corrects the frequency response of incoming speech signals by analyzing them using a speech analysis block, comparing against ideal speech characteristics, and applying adaptive frequency adjustments through a combination of filters to enhance intelligibility and quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If dynamic speech equalization is applied to improve speech intelligibility, then speech intelligibility and listening comfort are improved, but device complexity and computational requirements increase

Engineering Contradiction:
Improvespeech intelligibilityVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The speech signal is divided into multiple frequency bands using filter banks, allowing independent processing of different spectral regions. This segmentation enables targeted equalization of specific frequency ranges affected by channel impairments without requiring complex full-spectrum processing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts equalization parameters (filter coefficients, gain values) based on real-time analysis of the speech signal characteristics and estimated channel conditions. This adaptive parameter adjustment optimizes speech intelligibility for varying input conditions while maintaining computational efficiency through parameter optimization.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If frequency-dependent processing is applied to correct suboptimal frequency content, then speech quality is improved, but processing time and computational load increase

Engineering Contradiction:
Improvespeech qualityVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system pre-computes equalization filter coefficients and stores them for rapid retrieval during speech processing. By preparing processing parameters in advance based on typical speech characteristics and channel models, the system minimizes real-time computational requirements while maintaining high speech quality.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical or analog frequency processing systems with digital signal processing algorithms that can be efficiently implemented using software-based filter banks and spectral manipulation techniques, reducing hardware complexity and processing time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If adaptive filtering is used to compensate for channel impairments, then speech intelligibility is improved, but power consumption increases

Engineering Contradiction:
Improvespeech intelligibilityVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The equalization processing is applied periodically at optimized intervals rather than continuously, processing speech frames at rates matched to human speech variability. This periodic processing approach maintains speech intelligibility while significantly reducing computational power consumption compared to continuous real-time processing.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system applies equalization processing selectively to only those frequency bands and time periods where channel impairments are detected, rather than uniformly processing the entire speech signal. This partial processing approach reduces overall computational load and power consumption while maintaining effectiveness where needed.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3944237B1A loudspeaker system provided with dynamic speech equalization
Publication Date: 2024.10.02 EPOS GROUP AS
  • EP3944237B1 patent drawingFigure 1
  • EP3944237B1 patent drawingFigure 2
  • EP3944237B1 patent drawingFigure 3

AI summary

A method for speech equalization, comprising the steps of receiving an input audio signal, processing said input audio signal in dependence on frequency and to providing an equalized electric audio signal according to an equalization function, wherein said equalization function comprises at least an actuator part configured to dynamically applying a compensation filter to the received input signal and dynamically applying a transparent filter to the received input signal, and further transmitting an output signal perceivable by a user as sound representative of said electric acoustic input signal or a processed version thereof.