dB rating of horns and speakers in noisy rooms

[mshields]

I understand that 72 contains a requirement saying that you need to maintain 75dB or a certain amount of dB (I'm told it's 15dB) above the ambient, whichever is greater. If someone happens to know where that is I'd certainly appreciate the time savings.

Also, this question came up as it pertained to a school cafeteria. I think that if the fire alarm were to be triggered, the strobes would quiet that particular type of ambient noise considerably such that by the time the message was spoken, conditions would be acceptable. I don't even want to think about how many speakers we need to add including some in the ceilings to assure that we had 15dB above the ambient plus meeting the intelligibility requirements.

Thanks,

Mike

 

[cda]

are you asking about apples or oranges????

is this just an ordianry audio device, or are they installing a voice evac speaker with a message and whop and holler???

from the 2010 edition

18.4.3* Public Mode Audible Requirements.

18.4.3.1* To ensure that audible public mode signals are clearly heard, unless otherwise permitted by 18.4.3.2 through 18.4.3.5, they shall have a sound level at least 15 dB above the average ambient sound level or 5 dB above the maximum sound level having a duration of at least 60 seconds, whichever is greater, measured 5 ft (1.5 m) above the floor in the area required to be served by the system using the A-weighted scale (dBA).

18.4.3.2 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 18.5.

if just noral everyday sysem most auido devices can produce db level needed, and I would not reduce it because the children might shut up!!!!!

 

[mshields]

This particular instance involves voice evac in a school cafeteria.

and thanks

 

[cda]

ok so you want oranges

18.4.1.5* Voice messages shall not be required to meet the audibility requirements of 18.4.3 (Public Mode Audible Requirements), 18.4.4 (Private Mode Audible Requirements), 18.4.5 (Sleeping Area Requirements), or 18.4.6 (Narrow Band Tone Signaling for Exceeding Masked Thresholds), but shall meet the intelligibility requirements of 18.4.10 where voice intelligibility is required.

18.4.10* Voice Intelligibility. Within the acoustically distinguishable spaces (ADS) where voice intelligibility is required, voice communications systems shall reproduce prerecorded, synthesized, or live (e.g., microphone, telephone handset, and radio) messages with voice intelligibility.

18.4.10.1* ADSs shall be determined by the system designer during the planning and design of all emergency communications systems.

18.4.10.2 Each ADS shall be identified as requiring or not requiring voice intelligibility.

18.4.10.3* Where required by the authority having jurisdiction, ADS assignments shall be submitted for review and approval.

18.8 Textual Audible Appliances.

18.8.1 Speaker Appliances.

18.8.1.1 Speaker appliances shall comply with Section 18.4.

18.8.1.2* The sound pressure level, in dBA, of the fire alarm speaker appliance evacuation tone signals of the particular mode installed (public or private) shall comply with all the requirements in 18.4.3 (public) or 18.4.4 (private).

kind of my take on a voice evac system is the whoop has to meet the db level, and the voice message has to be understood, but maybe not to a certain db level>

at least that is my take on voice evac.

same comment with vocie evac if the company knows what they are doing they can achieve db level needed