voice evac system question

[cda]

using nfpa 72 2002 edition

Is there a requirement for a specfic db level, on the tones in the message, above ambient??

from 2007::: 7.4.1.4* Where required, voice communications systems shall be capable of the reproduction of prerecorded, synthesized, or live (e.g., microphone, telephone handset, and radio) messages with voice intelligibility.

also,

have you ever seen 7.4.2.2 used were it says visuals can be used in place of audio if approved??

7.4.2.2 Where approved by the authority having jurisdiction or other governing codes or standards, the requirements for audible signaling shall be permitted to be reduced or eliminated when visible signaling is provided in accordance with Section 7.5.

 

[AegisFPE]

Section 3.3.113.1 would define a speaker as an "audible notification appliance," therefore it would seem that the db provisions for the alert tones emitted by the devices should still be applicable. The revision with 2007 NFPA 72 7.4.1.6 appears to specifically address the voice portion of the audible signal, and does not exempt the alert tones from the other audibility requirements.

 

[FM William Burns]

Yes, in theaters where the initiation of the alarm shuts down the film projection and activates the interior lighting and in a couple of gymnasiums I've been in during an alarm.

 

[cda]

I think I know the answer after reading a little more.

Let me try to restate, does the tone on a voice evac have to meet the 15 db above ambient like a system with regular audio devices.

also, have you seen 7.4.2.2 : used before???

7.4.2.2 Where approved by the authority having jurisdiction or other governing codes or standards, the requirements for audible signaling shall be permitted to be reduced or eliminated when visible signaling is provided in accordance with Section 7.5.

 

[FM William Burns]

acoustic design practice and psychoacoustic research have long recognized that for a signal to be audible it need only penetrate the background noise in a one-third or a one octave band.

nfpa 72, 2002 [7.4.5]

 

[peach]

I think I know the answer after reading a little more.Let me try to restate, does the tone on a voice evac have to meet the 15 db above ambient like a system with regular audio devices.

also, have you seen 7.4.2.2 : used before???

7.4.2.2 Where approved by the authority having jurisdiction or other governing codes or standards, the requirements for audible signaling shall be permitted to be reduced or eliminated when visible signaling is provided in accordance with Section 7.5.

It's up to the jurisdiction, but you need to hear the warning above ambient when one is required... just failed on because you can't hear it.