Noise level from burning articles on the fireground

Firefighters encounter an extremely difficult environment due to the presence of heat, smoke, falling debris etc. If one of them needs rescue, an audible alarm is used to alert others of their location. This alarm, known as the Personal Alert Safety System (PASS) alarm, has been part of firefighter gear since the early 1980s. The PASS has been enormously successful, but a review of The National Institute for Occupational Safety and Health (NIOSH) firefighter fatality report suggests that there are instances when the alarm is not heard or not localized. In the past, we have studied fireground noise from various pieces of gear such as chainsaws and fans, etc., to understand the soundscape present during a firefighting operation. However, firefighters, and other interested parties have raised the issue of noise caused by the fire itself. The literature shows that buoyancy-controlled, non-premixed flames aerodynamically oscillate in the 10–16 Hz range, depending on the diameter of the fuel base. Surprisingly, few acoustic measurements have been made even for these relatively clean fire conditions. However, experience suggests burning items do create sounds. Most likely these sound are from the decomposition of the material as it undergoes pyrolysis (turns in gaseous fuel and char). This paper will present noise measurements from various burning articles as well as characterization of the fire to understand this noise source.