Acoustic reflectometry is a promising method of determining the geometry of unfamiliar passages, which can be described as an acoustic waveguide. In its basic form, this technique measures the acoustic pressure fluctuations generated by cross-sectional area changes in the waveguide. Knowing the time difference between the initial excitation of the waveguide and the magnitude of the reflected acoustic pressure pulse will give an estimate of the distance from the acoustic source, the area change at this distance, and potentially other geometric features which will be discussed further in this proposal. To that end, Brush Mountain Technologies will develop a method and device based on acoustic reflectometry to reconstruct waveguide geometries and will provide: 1. Models of acoustic input impedance of several simple cave/pipe/duct geometries to investigate the effect of geometry on impulse response. 2. Acoustic reflectometry signal processing algorithms to determine cave/pipe/duct geometries. 3. Demonstration of a prototype PC-based acoustic reflectometry device to determine cave/pipe/duct geometries. 4. (Phase I Option) Experimental testing prototype acoustic reflectometry device on more realistic geometries
