According to QCVN 21:2015/BGTVT part 1B, Chapter 2, section 10 and IMO standard MSC.311(88), when ships undergo long-distance trials, the sound pressure level of the fixed fire detection and alarm system must be measured.

The alarm sound pressure level of the fixed fire detection and alarm system at sleeping positions in the cabin and 1 m from the source must be at least 75 dB(A) and at least 10 dB(A) above the noise level. surroundings that exist during normal operation of the equipment with the vessel moving in mild weather. The sound pressure level should be within 1/3 octave range of the fundamental frequency. The audible alarm signal shall not exceed 120 dB(A).