Minimum fire alarm sound pressure level for elder care centres

Some building occupants cannot hear the activated fire alarm nor can they recognize the alarm, although the fire alarm system has been installed to the acceptable standard. Measurements of fire alarm sound pressure levels (SPLs) in five elder care centres showed that the sound output of a fire alarm can be depreciated after installation. The alarm level of a new fire alarm installation could alert most of the building occupants but could not awaken a sleeping person. Subjective ratings on the fire alarm audibility in terms of minimum fire alarm SPL were studied with 230 awaken subjects divided by two age groups (22-48 and 66-88) in the five elder care centres. A higher perceived SPL is preferred for the elder age group to obtain the same subjective rating, when compared with the younger age group. Correlations between the subjective ratings and the measured SPL show that the alarm SPL of 65 dBA can alert most of the occupants in daytime, but expressed a preference that the alarm SPL be increased. The results show that the minimum required fire alarm SPL is 74.5 dBA, which agrees with the recommended alarm SPL at bed head of 75 dBA in the design guidelines. The depreciation of SPL of alarm sounder and the preferred SPL of occupants should be considered in designing a fire alarm system for elder care centres.