Researchers use underwater listening devices (usually modified from those used by their former army to track submarines) to determine the exact source of these sounds made by whales. This method also allows them to detect how far these sounds can travel in the ocean. Dr Christopher Clark's research at Cornell University shows that the sound of whales can travel more than 3,000 kilometers through 30 years of military data. Just as whale songs provide information, data allows researchers to track whale migration paths during whale "singing" (mating) season.
Before humans appeared, Clark thought that these sounds of whales could spread from one side of the ocean to the other. His research also shows that environmental noise will double every ten years. This will reduce the spread of whale language by half. Those who think whale songs are of great significance to the welfare and continued reproduction of whales are particularly concerned about the possible harm caused by the increase of environmental noise. Other studies have shown that with the increase of shipping-for example, not far from Vancouver Port-some killer whales have changed their pronunciation tone frequency and increased their pronunciation volume, which is obviously an attempt to interfere with their voices. Environmentalists worry that this kind of sea activity will add too much physical strength to marine animals and cause difficulties to their spouses.