DOLPHINS, well known for their intelligence, are even cleverer than previously supposed. Marine biologists have discovered that when dolphins use sonar to track down prey, the creatures vary the volume of the acoustic clicks they broadcast according to their distance from a target. This helps them judge the size of the target as well as avoid uncomfortably loud echoes.
With any electromagnetic or acoustic signal, the further away a target is, the fainter the echo. Radars deal with this by making the receiver more sensitive the longer a signal takes to bounce back. Bats’ ears do essentially the same thing.…
