Please join us for the following AOS Seminar on Thursday, March 2nd at 4:00PM in Spiess Hall Room 330:
Speaker: Dr. Michael Buckingham, Scripps Institution of Oceanography
Title: "Propeller-aircraft, helicopters and jets as sound sources for investigating acoustic transmission across the air-sea interface"
Despite the acoustic impedance mismatch across the air-sea interface, sound does couple effectively from the atmosphere into the ocean. Low-flying aircraft can be heard underwater, and the sound that they transmit into the ocean can be used for underwater acoustics experiments. Propeller-driven light aircraft produce frequency components at about 100 Hz and above, and these transmissions have been used as the basis of an inversion technique for recovering the geo-acoustic properties shallow-water sediments. The infrasonic (≈ 10 Hz) and higher-frequency sounds from small helicopters excite the head wave in a shallow-water sediment, from which the sound speed in the sediment may be estimated; and a fast turbofan (jet) aircraft, flying at very low level, simulating a cruise missile, provides data to help develop an underwater, cruise-missile detection system. The mobility of the aircraft, relative to that of ships, is a significant advantage in underwater acoustics applications. Recent experiments with all three types of aircraft - propeller, helicopter and turbofan – will be described.
Snacks and refreshments will be available at 4:00 pm. Please bring your own cup.