46 CFR 76.27-20: -20 Alarm indicators.

(a) Audible alarms must generate sound pressure levels as set forth in 46 CFR 161.002 and must:

(1) Be at least 75 dBA as measured at the sleeping position in cabins;

(2) Be at least 10 dBA above ambient noise levels existing during normal operation with the ship under way in moderate weather when measured at a point 5 feet (1.5 meters) above the finished floor and at least 3 feet (1 meter) from the source;

(3) Not exceed 120 dBA; and

(4) The sound pressure level must be measured in the third octave band about the fundamental frequency.

(b) Visual alarms must generate light of an intensity and period as set forth in 46 CFR 161.002.

(c) All audible and visual alarms must be audible and visible throughout the spaces they are intended to alert.