Cetacean Finite Element Modeling (CFEM)

        Cetacean Finite Element Modeling (CFEM) is a project designed to investigate the interaction of marine mammal tissues with acoustic waves. We are presently working to improve techniques for measuring physical properties in marine mammal tissues, and to use these physical properties to construct computer models of whales. The models will then be acoustically excited and the model response measured.
        In this project, whale specimens are scanned with CT and MRI machines to provide geometric and density data. Acoustic velocity and strength measurements are made on tissue samples from various regions of a specimen. These data then will be mapped to a finite element model for analysis.
        We have conducted CT scans of a complete Ziphius cavirostris (Cuvier's Beaked Whale) and MRI scans of just the head section. We have simultaneously measured the acoustic velocity and strength of over 300 tissue samples from various regions of the specimen. We are currently working to correlate the CT data (Hounsfield numbers) with the velocity data so that a transfer function can be used to generate a full 3D velocity model of the whale.

For further information: Sean Wiggin's Acoustic Resonance Workshop slideshow.
Right photo is a tissue velocity measuring
apparatus. Acoustic travel time is measured with two parallel 10 MHz transducers, and distance is measured with calipers. Three orthogonal direction velocity (distance/travel time) measurements were made on each sample to investigate velocity anisotropy.
Left figure is a cross-axis slice from CT data of a Mesoplodon head. Hot colors are high density features, for example, bone. Air spaces are blue - note the eyes have been removed prior to scanning for other studies. Tissues are light orange and yellow.