Tyco 579-769 specifications Chapter Emergency Voice/Alarm Communications Systems

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Chapter 4

Emergency Voice/Alarm Communications Systems

Introduction

In this Chapter

An emergency voice/alarm communications system is designed to provide a highly reliable voice reinforcement and distribution network. These systems must deliver messages to building occupants for evacuation in an organized and safe manner. The system can deliver recorded messages automatically before emergency personnel arrive at the scene, and alarm paging systems can also be used to deliver live spoken messages from the emergency personnel to the occupants.

Refer to the page number listed in this table for information on a specific topic:

Topic	See Page #
A Typical Emergency Voice/Alarm Communications System	4-2
Parts of an Emergency Voice/Alarm Communications System	4-3

4-1

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Contents Fire Alarm Audio Applications Guide Page Copyrights and Trademarks Page Table of Contents Emergency Voice/Alarm Communications Systems Glossary of Terms Related Publications Chapter Speech Intelligibility Overview Speech Intelligibility Importance Designing for Topic See Page # Chapter Background InformationEquation 2-2. Ohm’s Law Equation 2-3. Power RelationshipsBasic Audio Math Equation 2-1. The DecibelEquation 2-6. Adding Decibels Equation 2-5. dB and Sound Pressure LevelsRobinson and Dadson Equal Loudness Curves Sound and HearingSpeech Pattern that Illustrates Modulations Nature of SpeechRoom Acoustics Eyring Equation, used when α Sabine Equation, used when αAreas with high ceilings, specify a more directional speaker Equation 2-8. The Inverse Square Law Speaker BasicsEquation 2-9. On-Axis SPL Calculation SPL = Sensitivity + 20 log6dB/division 87dBEquation 2-10. Directivity Factor Q for a Conical Source 51º Critical Polar Angle Calculations 104Listener Height = 1.5 Meters Ceiling Coverage Diameter Equation 2-11. Coverage Area CalculationsMinimum Overlap Layout Pattern Selection GuideSPL Variation by Layout Pattern 2x Edge-to-EdgeDistributed Wall Mounted Systems Width Opposite SpeakerWall Mounted Speakers In Meters Room Coverage Width Edge-edge Minimum-Overlap Full-Overlap Chapter Speech Intelligibility Frequency of Speech Contribution to Intelligibility Influences on IntelligibilityNo Noise With Added Noise Degradation of CIS vs. Signal-to-Noise RatioBackground Noise Reverberation Distortion Measures of Intelligibility Correlation of CIS and with STI and %ALconsALcons STI method with faster measurement times STI-CIS Analyzer Talkbox Practical Measurement of IntelligibilityTools for Predicting Intelligibility Page Chapter Emergency Voice/Alarm Communications Systems Advantages Typical Emergency Voice/Alarm Communications SystemParts of an Emergency Voice/Alarm Communications System Class a and B Speaker Circuit Wiring Chapter Regulatory Issues From Nfpa 72, 2002 Edition AudibilityHigh Background Noise Large Areas Intelligibility Intelligibility Certification Page Chapter Speaker System Design Method Determine the speaker-to-listener distance D2 Speaker Design MethodRecommendations for Maximizing System Intelligibility ITool Office Space Example Applying the MethodsOffice Space Speaker Location Guide Corridor Design Example Corridor SPL Distribution Corridor Speaker Location GuideITool Gymnasium Example 10. Gymnasium Speaker Location Guide 13. Lobby Example 15. Lobby Layout Applying the Methods Conclusion Page Chapter Glossary of Terms Glossary Glossary Page Index IN-2 Page 579-769 Rev. C