Tyco 579-769 specifications Chapter Regulatory Issues

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Introduction

In this Chapter

Chapter 5

Regulatory Issues

The governing specifications for the US Fire Alarm Market are found in the installation standard, NFPA 72® “National Fire Alarm Code.” The fire alarm audio system is defined within the class of “Notification Appliances.” NFPA 72 defines, among other things, requirements for audibility and intelligibility.

Some key specifications for the design of speaker systems are found in the “Notification Appliances for Fire Alarm Systems” chapter of NFPA 72.

IMPORTANT: This chapter contains excerpts of NFPA 72 2002 National Fire Alarm Code. Always verify which version of the code is enforced locally.

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

Topic	See Page #
Audibility	5-2
Intelligibility	5-4

5-1

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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 log87dB 6dB/divisionEquation 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 Opposite Speaker WidthWall 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 Correlation of CIS and with STI and %ALcons Measures of IntelligibilityALcons 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