1. Manatee psychoacoustics, habitat acoustics and boat noise. I have been working in this area with my business partner, Dr. Edmund R. Gerstein, since 1991. We measured the first behavioral audiogram on trained manatees. That was published in the J. Acoust. Soc. Am. We also measured masked thresholds, directional hearing, boat noise and acoustic propagation in manatee habitats. I hold a patent on a Manatee Alert Device that should enable manatees to better avoid boats. The device can use either linear or parametric array technology to produce directional sound that is not sound polluting and does not scare manatees. We also measured tug/barge noise and showed manatees do not get out of their way because they don’t hear them until it is too late under conditions where the manatees are submerged as the barge approaches them. I proposed that there is insufficient noise ahead of tugs/barges because of the accumulation effects of propagation of sound from the predominant noise source (the propellers) of sound spreading from the propellers, acoustic shadows caused by the position of the propellers above keel level and the cancellation of low frequency sound by the Lloyd Mirror Effect (a consequence of Snell’s Law). This work is continuing with a grant from the State of Florida.

2. Northern Right Whale ship collision avoidance is another topic Ed Gerstein, Steve Forsythe and I work on together. I postulated that the problem of large ship/cetacean collisions had the same acoustic causes as tugs/barges. Large ships also have their propellers above keel level. We measured these causes for large ships up to nearly 1,000 feet in length. This work is continuing under a Navy contract.

3. Dr. Rodney Rountree, Dr. Francis Juanes and I began working on soniferous fish location with an array on ROV’s. This work is in its second year (2002). First year results showed that ROV’s are noisy as soniferous fish locators. We believe, that as more soniferous fish work is funded, quiet ROV’s should be developed along with real-time tracking software for locating spawning grounds. Work has been funded by the Northeast Great Lakes Center of the National Undersea Research Program.

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