Gray whales echolocate at frequencies up to 200kHZ in the wa…

Gray whales echolocate at frequencies up to 200kHZ in the water.  The distance between their ears is about 9m.  A sound made at 20Hz produces a wavelength of what in water?  Would gray whales be able to localize this sound using intensity cues, phase differences or neither?  (Remember that speed of sound in water is 1350m/s).