  A compartment fire (a fire in a room or building) creates temperature
gradients and inhomogeneous time-varying temperature, density, and flow fields.
This work compared experimental measurements of the room acoustic
impulse/frequency response in a room with a fire to numerically modeled
responses. The fire is modeled using Fire Dynamics Simulator (FDS). Acoustic
modeling was performed using the temperature field computed by FDS. COMSOL
Multiphysics was used for finite element acoustic modeling and Bellhop for
ray-trace acoustics modeling. The results show that the fire causes wave-fronts
to arrive earlier (due to the higher sound speed) and with more variation in
the delay times (due to the sound speed perturbations). The frequency response
shows that the modes are shifted up in frequency and high frequency (>2500 Hz)
modes are significantly attenuated. Model results are compared with data and
show good agreement in observed trends.
