It is no secret that our world is getting louder and louder. Hearing loss in teens is on the rise; noise pollution in our cities is at an all-time high; and now, even our oceans and sea mammals are affected by the constant noise of our industrial world. Marine scientists at the University of South Florida in St. Petersburg and Mote Marine Laboratory published a study November 3 in the Public Library of Science linking mass strandings of whales and dolphins to hearing loss.

Researchers looked at eight species of cetacean and found that 57 percent of bottlenose dolphins and 36 percent of rough-toothed dolphins suffered from severe to profound hearing loss. Because these species rely on echolocation for orientation and feeding, researchers think hearing loss plays a significant role in some strandings.

The study comes on the heels of one of the biggest mass deaths of cetaceans in Irish history when at least 33 pilot whales beached themselves on the northwest coast of County Donegal over the first weekend in November.

So what makes the ocean so noisy?

The main factor is noise from commercial shipping. Rumblings of noise from these massive ships permeate the ocean for miles and miles, affecting marine mammals’ ability to communicate. Other noises include underwater explosions or seismic testing. Earlier this year, north Atlantic right whales were found to be calling more loudly to each other apparently in order to compensate for the constant underwater noise.

Other factors contributing to hearing loss in marine animals include birth defects, age and antibiotic drug treatment. Some emerging research shows that exposure to the chemical PCB could also hinder hearing developments in dolphins.

Navy sonar is thought by some to be another possible contributor to hearing loss in marine animals because the sound is so loud. However, a study in 2006 found no link between Navy sonar and whale strandings.