Where We Work: Naval Submarine Medical Research Laboratory I am a hearing researcher at the Naval Submarine Medical Research Laboratory (NSMRL) in Groton, CT, surrounded by sailors who can go for months without seeing the light of day. The Navy has a long track record of funding auditory research, and it is one of the few non-academic career ... Features
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Features  |   January 01, 2006
Where We Work: Naval Submarine Medical Research Laboratory
Author Notes
  • Lynne Marshall, is a senior research scientist and leader of the Hearing Conservation Team at the Naval Submarine Medical Research Laboratory, which is housed at the Naval Submarine Base in Groton, CT. Before working for the military, she worked at university teaching hospitals and at the University of Nebraska at Omaha where she availed herself of the proximity of Boys Town National Research Hospital.
    Lynne Marshall, is a senior research scientist and leader of the Hearing Conservation Team at the Naval Submarine Medical Research Laboratory, which is housed at the Naval Submarine Base in Groton, CT. Before working for the military, she worked at university teaching hospitals and at the University of Nebraska at Omaha where she availed herself of the proximity of Boys Town National Research Hospital.×
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Hearing Disorders / Research Issues, Methods & Evidence-Based Practice / Features
Features   |   January 01, 2006
Where We Work: Naval Submarine Medical Research Laboratory
The ASHA Leader, January 2006, Vol. 11, 44. doi:10.1044/leader.FTR4.11012006.44
The ASHA Leader, January 2006, Vol. 11, 44. doi:10.1044/leader.FTR4.11012006.44
I am a hearing researcher at the Naval Submarine Medical Research Laboratory (NSMRL) in Groton, CT, surrounded by sailors who can go for months without seeing the light of day. The Navy has a long track record of funding auditory research, and it is one of the few non-academic career paths for audiology researchers.
The Navy environment has provided me with interesting research opportunities that would be difficult to find elsewhere. My first research projects at NSMRL, beginning in the 1980s, were in psychoacoustics and speech perception, including classified auditory sonar work. My colleagues and I tried different signal-processing tricks to improve sonar operators’ ability to detect, discriminate, and classify important signals buried in the noise of the ocean-some of these ideas were borrowed from hearing-aid schemes.
Those talented sonar operators had very little time to spend in our lab, so we had to use time-efficient procedures. Our research compared permutations of standard audiometric threshold procedures to psychoacoustical laboratory procedures. From this I gained a deep appreciation for the Carhart-Jerger adaptation of the Hughson-Westlake technique, which is universally used by audiologists.
For one project, I worked with a multidisciplinary team looking at the effects of low oxygen on human performance. In another large-team study of around-the-clock intermittent high-level noise exposure, my job was to measure speech-recognition ability. Susan Norton, a colleague (now director of audiology at the Children’s Hospital and Medical Center in Seattle), thought this was “too cool,” and suggested adding otoacoustic emissions (OAEs). After a quick apprenticeship with Dr. Norton, I added OAEs to my already long days and nights.
I eventually developed a large research program investigating the use of OAEs in hearing-conservation programs. The approach I take is different from that of many other OAE researchers in that I monitor groups of noise-exposed people over a number of years to see what happened to their OAEs and hearing thresholds. I thought that OAEs could be more sensitive to the early stages of noise-induced hearing loss (NIHL), and that OAEs may show changes before any permanent thresholds shifts (PTS) were seen in the audiogram. Furthermore, OAEs may even be predictive of NIHL, and they could be used to identify people at most risk. These people could then receive early intervention to prevent NIHL.
Investigating NIHL
To minimize the time and expense of large-scale, longitudinal studies requires access to populations who are at risk for getting NIHL in a short amount of time. Even so, it can take years for NIHL to develop in enough people to have sufficient data for satisfactory data analyses. Being based in a military research lab, I have easier access to unique at-risk populations.
Our first longitudinal OAE study enrolled 474 people who worked at our submarine base or in the surrounding community. Many of the most at-risk people were in the submarine repair facility. One of the most difficult jobs, which required a lot of networking, was to find a relatively young, non-noise- exposed control group. Some were recruited from my yoga class. Both had to be dropped when one joined a rock band and the other started flying light aircraft.
Later, I grabbed the chance to study an aircraft carrier crew, before and after a six-month deployment where there were numerous flight operations. Data collection for our seven-member team was intense-six to seven days per week for three weeks for the pre-deployment data collection, often starting before dawn and ending after dusk.
Regulations prevented us from cash compensation of the volunteers, but we were allowed to distribute appropriate equipment. A choice of hearing protection along with individual plastic carrying cases turned out to be status symbols on the ship. A highlight of this field study was the chance to go out to sea for three days of intensive flight training. I was able to watch activity on and below the flight deck and experience the noise levels. Then, I got to go home in a C-2 transport aircraft that was catapulted off the flight deck. Not the typical daily commute!
We also did a similar study with Marine recruits in San Diego before and after basic training. At the initial test, keeping the sleep-deprived Marines awake long enough to complete an audiogram was reminiscent of pediatric audiology.
Here at NSMRL I am able to do lab-based research as well as field studies. We are currently working with an equipment manufacturer to develop OAE equipment more suited to adult hearing-conservation programs. We have two other current projects that don’t use OAEs. One will develop personalized, realistic NIHL simulations, using sound cuts chosen by each person to be individually significant. We intend for it to be efficient enough for routine use in audiology clinics.
Our other project combines audiology and economics. Our team is building an algorithm for military-system designers to estimate the economic cost of NIHL attributable to the deployment of their system. We hope that in Washington, where money has a loud voice, our algorithm will cause designers to save money by saving hearing.
Most of the research we do has a strong applied focus, as we try to develop solutions to military health problems. The success of our research programs is partly due to the strong collaborations we have with equipment manufacturers, universities, and other military labs. Our research not only supports the health and safety of our troops, but the technology and information we develop has use throughout society as hazardous noise exposure is pervasive in our modern world.
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January 2006
Volume 11, Issue 1