Audibility of Emergency Broadcasting Sounds in Mechanical and Electrical Rooms in Office Facilities

Abstract

For the clear presentation of fire warning and emergency broadcasting sounds to occupants of buildings, certain guidelines and requirements have been established. However, the parameters to evaluate the speech intelligibility of the generated sound have not been established. In the NFPA 72 and BS standards, a specific warning sound level for warning sounds in residential facilities is proposed and the speech transmission index (STI) for emergency broadcasting systems is regulated. Mechanical and electrical systems need to be maintained to supply water and electricity in fire and disaster situations. To maintain these functions in buildings, emergency broadcasting sounds need to be clearly delivered to workers in the facilities. For the clear understanding of emergency broadcasting sounds, the background noise in the facilities should be lower than the broadcasting sounds. In addition, broadcasting sounds should not reverberate. In this study, the noise characteristics in the mechanical rooms and electricity facilities of office buildings that were more than 40 years old were measured and used for the acoustic prediction of emergency broadcasting sounds. Audibility and room acoustic properties, such as the reverberation time and STI in the facilities, were simulated by using the room acoustic simulation method. The audibility and STI of emergency broadcasting sounds were evaluated as “bad” or “poor” under the basic conditions. For the clear delivery of emergency broadcast sounds in mechanical and electrical rooms, it is necessary to apply a sound-absorbing material on the walls and ceilings in the facilities to reduce the reverberation. At the same time, an increase in the volume of emergency broadcast sounds and the introduction of additional speakers should be considered.