📢 NFPA 72 Annex D Speech Intelligibility (STI >0.50 / CIS >0.70 Target Acoustically)

Emergency Voice Evacuation (STI / CIS) Calculator

Model Emergency Voice-Alarm Communication System (EVACS) acoustic audibility and speech intelligibility under NFPA 72 Annex D & IEC 60268-16: calculate Speech Transmission Index (STI ≥ 0.50) and Common Intelligibility Scale (CIS ≥ 0.70 across acoustically distinguishable spaces ADS), size 25V/70V distributed speaker taps, and life safety profits.

1. Project & Operating Inputs

Acoustically Distinguishable Spaces ADS (Space Count e.g. 18 Zones)

Ambient Sound Level (dBA e.g. 68 dBA Active Office / Corridor)

Customer Bid Price for Supplied & Commissioned EVACS System ($)

70V Amplifiers, Fire Alarm Speakers, NTi Audio STI Meter & Tech ($)

2. Financial Breakdown & Yield

NFPA 72 SPEECH INTELLIGIBILITY (STI)

Turnkey EVACS Voice Audio Profit

Acoustic Life Safety Margin

0.0%

Gross Revenue / Bill

Total Project CapEx

Operating / Material Cost