Abstract
Functional Magnetic Resonance Imaging (fMRI) offers great opportunities to learn how a dolphin’s brain processes acoustic echolocation and communication signals. Delivering sound to an animal in a fMRI requires a sound delivery system with no ferrous metal. This thesis proposes an approach that generates sound far from the fMRI magnet, then propagates the sound through a waveguide to the dolphin roughly 10 meters away. The waveguide needs to function at two frequency ranges for echolocation signals (80kHz) and communication signals (10kHz to 20kHz). This approach has two challenges: will there be enough energy for the dolphin to hear the acoustic signals, and will the received signal be distorted? The waveguide attenuates energy due to absorption and friction. The impedance mismatch between the boundary of waveguide and the dolphin also loses energy. Filling the waveguide with water limits the transmission loss through the waveguide but causes the waveguide’s radial boundary condition to be pressure release. When the radial boundary is pressure release, all modes trapped in the waveguide will have dispersion. Distortion due to dispersion will be minimized through equalization.