Acoustic transmitters, commonly used to track fish, give researchers an idea of what’s happening beneath the waves. They receive a signal every time a tagged animal passes by a fixed acoustic receiver. Since the researchers know where the receivers are, they get a better sense of where these animals travel. What’s not known is how the acoustic “pings” that these tags produce influence nearby animals that have sensitive hearing (like marine mammals). Is the sound like a dinner bell, attracting potential predators? Or is it like a warning, repelling skittish animals? The belugas, along with the Pacific white-sided dolphins and harbour porpoises at the Aquarium, are part of a research study to test their hearing range and ability to detect acoustic tags.