Blue whales travel huge distances and need to keep in touch with other blue whales across miles and miles of ocean. To do this they produce a very, very low frequency noise. It is very low so that it can travel more easily through the water and it is also very powerful. Your voice can probably make a sound of 100 decibels if you shout loudly. The sound of a jet plane is about 150 decibels and a blue whale's sound can be as loud as 188 decibels. It is the loudest sound ever known to be produced by a living source and because it is so low it is like feeling an earthquake!