Audio Intelligibility via Localized SPL Adjustment

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Solution Overview

Problem

In large spaces, reverberation significantly reduces the intelligibility of audio signals emitted from multiple audio output devices, making it difficult for people to understand vocal messages or warnings due to the muddying effect on the emergency signals.

Innovation Solution

A method and system that involve selecting and generating test signals to determine the amount of reverberation at various microphone locations, adjusting the sound pressure level (SPL) settings of audio output devices based on the reverberation measurements, and optimizing the intelligibility of audio signals by lowering the SPL of devices with high reverberation and raising it for those with low reverberation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple audio output devices are deployed in large spaces to ensure minimum sound pressure level coverage, then the area coverage and reliability of emergency notification is improved, but the intelligibility of vocal messages deteriorates due to excessive reverberation

Engineering Contradiction:

Improveemergency notification coverageVSAvoidmessage intelligibility

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent applies local quality by adjusting the SPL settings of individual audio output devices based on their specific reverberation characteristics. Each speaker is measured at multiple microphone locations and assigned a customized SPL setting rather than using a uniform setting across all devices. This localized optimization allows the system to maintain reliability through comprehensive coverage while improving intelligibility by reducing reverberation effects in specific high-reverberation zones.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If the sound pressure level of audio output devices is increased to overcome reverberation effects, then the sound coverage is improved, but the reverberation duration increases and further reduces intelligibility

Engineering Contradiction:

Improvesound pressure levelVSAvoidreverberation duration

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent applies parameter changes by measuring the reverberation characteristics of each audio output device and adjusting its SPL setting accordingly. The system calculates a reverberation metric for each speaker based on measurements from multiple microphone locations, then modifies the operating parameters (SPL settings) of individual devices to optimize the balance between sound coverage and reverberation control. This data-driven parameter adjustment resolves the contradiction by preventing excessive SPL increases that would extend reverberation duration.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If uniform SPL settings are applied to all audio output devices for simplicity, then the system complexity is reduced, but the intelligibility optimization is compromised due to varying reverberation conditions in different locations

Engineering Contradiction:

ImproveSPL configuration complexityVSAvoidmessage intelligibility

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent implements local quality by transitioning from uniform SPL settings to location-specific configurations. Each audio output device is evaluated based on its acoustic environment and assigned a customized SPL setting derived from reverberation measurements at multiple microphone locations. This approach increases device complexity in terms of configuration but dramatically improves message intelligibility by accounting for varying reverberation conditions throughout the space.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system employs feedback by measuring reverberation characteristics at multiple locations and using this information to adjust SPL settings. The process involves capturing acoustic responses, calculating reverberation metrics, and feeding this data back into the SPL configuration for each audio output device. This closed-loop approach optimizes intelligibility while providing a systematic method to manage the increased complexity through automated measurement and calculation.

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 improves the intelligibility of audio signals in reverberant environments by optimizing the SPL settings of audio output devices, ensuring that critical messages or warnings can be clearly heard, even in spaces with severe reverberation issues.

Implementation Method 1

there may be so much reverberation that it is near impossible to understand any vocal messages or even understand what sound is being broadcast throughout the space

Methodology Applied

Scientific EffectReverberation: Reverberation

Implementation Method 2

converting sound to an electrical signal at each microphone

Methodology Applied

Scientific EffectAcoustic to electrical conversion:

Data Source

PatentUS11470433B2Characterization of reverberation of audible spaces

Publication Date: 2022.10.11 TYCO FIRE & SECURITY GMBH

AI summary

A method and system for improving the intelligibility of an audio signal emitted from plural audio output devices in a space can help mitigate systems that have low intelligibility at installation due to reverberation effects; it can provide a quick post installation check of a system prior to a full-fledged STIPA (Speech Transmission Index for Public Address Systems) or equivalent test; and it allows for a quick verification if changes to the acoustical environment are expected to have major effects on STIPA tests.