The principal objective of this project is to demonstrate how BATSCAN, a remote acoustic tomography software developed by Greene Research and Development International, can be modified to pinpoint the location of human sound sources beneath rubble. This application is appropriately named, SR-VIVES (Search & Rescue- Victims in Various Emergency Situations).

We predicted that by averaging the attenuation and velocity of sound through variable-density media, we would be able to accurately pinpoint a calibrated noise source through similar media using BATSCAN.

In order to achieve this goal, the velocity and attenuation of sound were experimentally determined through different soil densities. BATSCAN can use this data to triangulate sound of varying spectral densities to within 3 cm. Moreover, BATSCAN can differentiate a sound source from background noise with a signal to noise ratio of up to -25 dB.

In order to understand the frequency band of a human scream, we applied a variation of BATSCAN to a microphone array and analyzed the frequencies and overtones of a distress call.

The attenuation of sound was measured through a PVC tube filled with air and different densities of soil. The velocity was determined by measuring the resonation of sound waves within a smaller PVC testing apparatus using a LabVIEW. The velocity and attenuation of white noise (all frequencies of equal intensity) were then integrated with BATSCAN in order to locate the aforementioned distress call within a reverberant chamber with an accelerometer array.

As we had hypothesized, we found that the velocity of sound was much faster through soil than in air. However, we did not expect the velocity of sound to have a linear relationship with the density of soil through which it propagates. We also showed that by characterizing the velocity of sound through a known medium (i.e. soil, air, rubble), we could pinpoint a sound source with BATSCAN within a similar density medium.

Our research will lay a foundation for future rescue operations in order to identify where disaster victims may lie in a timely and efficient manner. Beyond the sniff of a rescue dog, beyond the reach of a nearby helper, SR-VIVES will go beyond the status quo and be the difference between life and death.