Harbor porpoise echolocation clicks originally recorded on a tagged porpoise during a prey capture experiment. Listening, you can hear some clicks, then a series of faster clicks (the buzz) around the time of capture. After capturing the fish, the porpoise goes back to slower clicking. Note: This sound has been modified to be audible to the human ear. Thus, what you hear when you listen is the real rate at which the porpoise made the clicks, but not the actual clicks (which are ultrasonic).
Sound courtesy of Stacy DeRuiter, Woods Hole Oceanographic Institution. Released under Creative Commons License, non-commercial attribution.