Groton — For 75 years, scientists have been pioneering medical research at the Naval Submarine Medical Research Laboratory  that is designed to improve the health, safety and performance of submariners.

The lab on Wednesday will celebrate its 75th anniversary, which was on June 25, with a ceremony at the Submarine Force Library and Museum. Scientists on Monday offered a tour to the media, highlighting some of their research into wearable technologies, hearing preservation, decompression and underwater exercise.

The lab’s anechoic chamber, a large cube made of cinderblock and fiber glass that absorbs sound, eliminates any background noise or echoes within the space. In this chamber, scientists study how different types of hearing protection equipment work with the goal of preventing hearing loss and damage, a common disability among military members. 

Sailors participating in these studies sit in the center of the room and are asked to identify which of the room’s 180 small speakers a sound is coming from. This helps researchers identify how protective equipment impacts sailors’ abilities to locate where different sounds are coming from. 

“We study this to make sure that the devices we use to protect people’s hearing don’t impact their ability to tell where sounds are coming from,” said research engineer Derek Schwaller, and “to make sure that they are not missing any cues of something that might be dangerous.” 

Dr. Stephanie Karch, a research audiologist, said that the goal of this research is to prevent hearing loss and understand which hearing protection devices are best for certain individuals and particular environments.

In other sound related experiments, research physiologist and warfighter performance department head Dr. Brandon Casper explained how scientists test the impact of underwater explosions on divers to, hopefully, “reduce any risk of divers being hurt underwater by noise like sonar and underwater explosives.” 

Scientists deploy seismic air guns, which are detonated in a large tank of water, to simulate the sound of explosions divers might hear underwater. The blast causes the tank to lift off the ground for a few seconds. 

For the study, scientists use a dummy named Quint — a replica of a human torso that includes a full skeletal system and organs — to see how explosions and sonar will affect someone who hears them under water. Other tests use a dummy’s head, fitted with microphones in the ears, inside a diver’s helmet to determine how much sound actually reaches a diver's ears. 

“These studies help us make recommendations so that divers are able to complete their missions and stay safe,” said Casper.

In another part of the lab, divers go underwater in a 10-foot-deep pool and ride an exercise bike. While they ride the bike — usually for about 90 minutes — a tablet attached to the bike asks them questions that help scientists assess their decision-making skills, their response time and their overall cognitive function. 

Researchers can alter things such as the temperature of the water, the speed and resistance of the bike, and the thickness of the divers’ wetsuits to see under what conditions they perform best, said research psychologist Dr. Justin Handy. The goal, Handy said, is to see how physical exertion underwater affects divers’ thinking.

The lab is also home to the Genesis hypo/hyperbaric chamber, which scientists are using to help improve the decompression process for divers. 

The chamber, which simulates a submarine or deep sea environment, pioneered research in the 1950s and 1960s that helped scientists understand how divers can more safely resurface.

“And it all started right here,” said diving research department head Louis Deflice, recognizing the role the Groton research lab has had on diving research around the world. 

Typically, said Deflice, it takes about one day of decompression for every 100 feet a diver dives. That means that if divers go down 1,000 feet, it can take more than ten days for them to resurface safely. If a submarine malfunctions, or there is an emergency, divers may need to get back to the surface much more quickly than that. 

The research being done in Groton is helping scientists understand how to help divers who find themselves in emergency situations. The chamber is currently undergoing extensive renovations, with plans to resume human experiments in the chamber next March, said scientific director Dr. David Fothergill.

Their overall goal with this research, said Fothergill, is “to provide more survivability to divers in an emergency situation” and make the decompression process easier and safer. 

“The research we do is critical for our undersea warriors to ensure they perform their missions safely,” he said. 

In other parts of the lab, scientists like research physiologist Dr. Jeffrey Bolkhovsky are working on wearable technologies like watches and glasses that monitor physiological responses such as heart rates, sweat, eye movements and facial expressions. 

These devices can help scientists understand when and under what conditions individual people perform best to help improve individualized scheduling, said Bolkhovsky.

The glasses can also help alert others to emergency situations on submarines by monitoring the facial expressions and emotional reactions — like anger or surprise — of the people wearing them. If a group of people working in the same area all express fear or surprise simultaneously, others aboard the submarine can take note of that reaction and potentially be alerted to an emergency more quickly, said Bolkhovsky. 

Commander Joseph Decicco, department head for the submarine medicine and survival systems, said that another study involving wearable technology looks at how submariners’ circadian rhythms are impacted by being underwater for long periods. 

The Navy is using blue light glasses and blue light blocking glasses to help submariners — working without access to sunlight for long periods of time — sleep better and be more alert at the start of their day, by simulating daytime and nighttime with blue light.

This type of physiological monitoring is meant to help the Navy individualize schedules and practices to make submariners’ jobs safer and improve their performance, by understanding how they work best.

“We want to try to make their lives easier, we want to try to give them the best tools that they have on hand in order to function the best underway,” said Bolkhovsky. 

Last week, Gov. Ned Lamont issued a proclamation, naming June 25 as Naval Submarine Medical Research Laboratory Day.

The Navy will host a ceremony at the museum on Wednesday. The ceremony will include speeches from several naval scientists involved in the lab’s research and celebrate the lab’s anniversary.

t.hartz@theday.com