PASS Audibility Project
Modeling and Validation of Sound Transmission
Using the passive sonar equation approach, the transmission loss (TL) represents the attenuation of the PASS signal in the fireground environment. This portion of the research focuses on the losses through the air due to various effects, such as chemical composition, temperature gradients, etc. We approached this using the following method:
Conclusion
Using the modeled and calculated transfer functions, we are trying to find a way to quantitatively determine how the signal changes in a burning environment. Experimentally, the change is easy to hear; listen for yourself below.
A simple analytical model was created using modal analyses of stratified layers of temperature graded air. A more complex numerical model (image shown below) was created in COMSOL with the aid of the Fire Dynamics Simulator (FDS) fire model (shown left).
To validate the model above, we took transfer function measurements in a controlled compartment fire at the University of Texas burn facility. A 150 kW fire was used.