Effect of fire and high temperatures on alarm signals

Firefighters use an acoustic alarm to recognize and locate other firefighters that need rescue. The alarm, codified under NFPA 1982 : Standard for Personal Alert Safety System (PASS), is typically implemented in firefighter’s SCBA (self-contained breathing apparatus) and is carried by a majority of firefighter in the United States. In the past, the standard specified certain frequency tones and other parameters and left implementation up to manufacturers, leading to an infinite number of possibilities that could satisfy the standard. However, there is a move to converge the standard to a single alarm sound. The research presented provides science-based guidance for the next generation of PASS signal. In the two previous ASA meetings, a number of experimental and numerical studies were presented regarding the effect of temperature stratification on room acoustics. The present work uses models developed under those studies to quantify the effect of various signal parameters (frequency ranges, time delay bet...