Sharks at the Loveland Living Planet Aquarium in Draper, Utah, glide silently behind glass walls — but just how silent is their world? A team of BYU researchers set out to discover how much of the aquarium’s daily bustle filters into the shark tank, and whether that noise is affecting the animals who call it home.
The aquarium welcomes nearly one million visitors each year. While facility managers carefully control visitor noise and background music, the aquarium has never been able to accurately measure the amount of sound that passes through the glass and water. The uncertainty posed a real question: Could even well-managed human noise still disrupt the natural environment of aquatic animals?
“While we have tools for measuring sound in the air, the behavior of sound underwater is totally different,” Ari Fustukjian, the vice president of zoological operations at the aquarium, said. “We want to really understand how sound works in this space and interacts with the animals.”
In collaboration with the aquarium and the BYU Acoustics Research Group, led by Professor Traci Neilsen, BYU student researchers confirmed that although noise does travel into the fish tanks, the sound levels remain well within a healthy range for the animals.
To measure sounds within the tanks, BYU researchers couldn’t use standard microphones, which are designed for air. Because sound travels faster and more intensely in water, they used specialized hydrophones that detect sound pressure in liquids and convert it into electrical signals.
“A hydrophone is an underwater microphone. These were placed very close to the acrylic walls and then in the water. On the other side, we had sound level meters that were reading the level in the rooms that could then be compared to the levels in the tank,” Neilsen explained.
BYU students placed hydrophones at various locations in the tank to track the distance sounds traveled underwater. They played a variety of noises in the viewing area, from white noise to high-pitched chirps, to see which sounds carried into the habitat.
Fish don’t hear the way humans do, and sharks are especially unique. They detect lower-frequency sounds and “hear” with their whole bodies. A network of sensory cells along their sides enables them to detect vibrations and movement in the water.
“With their unique hearing, sharks can detect animals in the water from miles away,” Madilyn Randall, the lead student researcher, said. “Because of their heightened senses, they would be the first animals to key into any disruptive sounds.”
Randall and her team found that sound from both the viewing area and the tank’s maintenance system did, in fact, travel through the water. Their hydrophones primarily picked up lower-frequency sounds, suggesting that higher-pitched noises don’t make it into the tanks. Interestingly, the low-frequency sounds that traveled best through water lie within the same range as human speech and the sharks’ natural hearing range.
With few aquarium-based studies having been conducted, Nielsen recognized that this was a unique opportunity to partner with the aquarium.
“Our findings were a tool that the director of the aquarium was able to use in building a new, large tank in their new facility. He was able to use this as evidence that the filtration system in the new tank should be higher quality and have a lower background noise level,” Neilsen said.
Fustukjian says the goal of the project wasn’t just to congratulate themselves for maintaining safe noise levels at the aquarium, but to gather insights that would help them continue raising the standard of animal care.
“At our heart, we are an educational organization,” Fustukjian said. “It is our mission to facilitate education and pursue scientific investigation. This type of scientific collaboration with groups like BYU is really the whole point.”
That collaborative spirit also opened doors for BYU students like Randall, who was one of the few undergraduate students nationwide to present her findings at the Acoustical Society of America Conference in New Orleans this May.
“I hope that in my future career I can continue making an impact using acoustics,” Randall said. “Acoustics crosses over into almost every type of science. It affects how we feel — how happy we are.”
The research was sponsored by the College High Impact Research Proposal Funding (CHIRP), and College support for the undergraduate research assistants was provided by generous alumni donations.
