A recent paper by Paul Nachtigall and Alexander Supin describes how a false killer whale is able to lower its hearing sensitivity before a loud sound when given a warning beforehand. Because many marine animals depend on their hearing for feeding and communication, loud sounds in the environment can have an impact on these animals. False killer whales and other odontocete (such as beluga whales and dolphins) use echolocation to find their food. They send out sound pulses and listen for a return echo from the prey. The echolocation signals they send out can be very loud, while the return signal may be very soft. Previous research demonstrated that at least some toothed whales can change their hearing sensitivity when echolocating, reducing it when sending out and increasing it when listening.
The new paper measured the brain signals of a false killer whale to demonstrate that the whale will reduce its hearing sensitivity when a warning sound precedes a loud sound. The whale learned that the warning sound indicated a loud sound was coming and the whale was able to reduce its hearing sensitivity in anticipation of the loud sound.
This research may be a very important clue to helping mitigate potential effects on some marine mammals from loud sounds people make in the ocean. The mitigation of loud sounds is a great concern for many ocean activities such as pile driving (building in the ocean), seismic surveys, and shipping.
Further reading on DOSITS:
- Paul E. Nachtigall, and Alexander Ya. Supin 2013, "A false killer whale reduces its hearing sensitivity when a loud sound is preceded by a warning." The Journal of Experimental Biology.