of "blade noise" from a large oceanographic vessel. The spectrograms
show the acoustic signature of the NOAA Ship Ronald H. Brown
as it approaches five different hydrophone sites in the equatorial
Pacific Ocean. The spacing of the blade lines is generally
consistent in each example. Acoustic signatures are routinely
used by the military to identify ship characteristics, class,
and often individual vessels.
for full-sized image.
recorded signal has been sped up 10 times)