Some scientists say that animals in the ocean are increasingly threatened  by noise pollution caused by human beings. The noise that affects sea animals comes from a number of human activities. Such noises are added to natural sounds. These sounds include the breaking of ice fields, underwater earthquakes, and sounds made by animals themselves. Decibels  measured in water are different from those measured on land. A noise of one hundred and twenty decibels on land caused pain to human ears. In water, a decibel level of one hundred and ninety-five would have the same effect. Some scientists have planned to set a noise limit of one hundred and twenty decibels in oceans. They have found that noises at that level can frighten and confuse  whales. A team of American and Canadian scientists discovered that loud noises can seriously hurt some animals. The research team found that powerful underwater explosions were causing whales in the area to lose their hearing. This seriously affected the whales' ability to exchange information and find their way. Some of the whales even died. The explosions had caused their ears to bleed and become infected. Many researchers whose work depends on ocean sounds disagree to a limit of one hundred and twenty decibels. They say such a limit would mean an end to important industrial and scientific research. Scientists do not know how much and what kinds of noises are harmful to ocean animals. However, many scientists suspect  that noise is a greater danger than they believed. They want to stop noises from harming creatures in the ocean. We can know from the passage that many scientists think that the noise limit  of one hundred twenty decibels would   _  .
stop them from doing their research work benefit them a lot in their research work do good to their health increase the industrial output