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   Ask an Acoustician: Zoi-Heleni Michalopoulou
Zoi-Heleni Michalopoulou and Micheal L. Dent
    Meet Zoi-Heleni Michalopoulou
This “Ask an Acoustician” essay features Zoi-Heleni (Eliza) Michalopoulou from the Department of Math- ematical Sciences, New Jersey Institute of Technology (NJIT; Newark). Eliza is a member of the Acoustical Oceanography, Acoustical Signal Processing, and Under- water Acoustics Technical Committees of the Acoustical Society of America (ASA). She is a Fellow of the ASA and has been a member of the College of Fellows, cochair of the Women in Acoustics Committee, and an associate editor for The Journal of the Acoustical Society of America. I will let Eliza tell you the rest in her own words.
A Conversation with Zoi-Heleni Michalopoulou, in Her Own Words
Tell us about your work.
I listen to the ocean! Employing both acoustic models and statistical signal processing, I conduct research in geoacoustic inversion. That is, I solve the inverse problem, estimating properties of the seabed with which the sound has interacted. The forward problem in ocean acoustics, in simple terms, entails the modeling of the sound that travels in the ocean using mathematical relationships and relying on physics; the models connect sound propaga- tion to the location of the source that transmits the sound, the placement of the receivers where the sound is sensed, and ocean environment parameters such as properties of the sediments. The inverse problem, on the other hand, uses these forward models and recorded data to move backward, that is, to identify the properties that gener- ated the measured sound.
Geoacoustic inversion is one aspect of the inverse problem. My interests extend to inversion for source detection and
location as well, both of which are inherently tied with geoacoustic inversion. Knowing the propagation environ- ment, determined to a large degree by the seabed structure obtained via geoacoustic inversion, allows us to better detect, identify, and localize sources of interest in the ocean, whether these are submarines or sound-producing marine life. These tasks are of paramount importance in antisubmarine warfare and the study of marine life.
I see my work as a combination of underwater acoustics, acoustic signal processing, and acoustical oceanography, reflected in the three ASA technical committees of which I am a member. Recently, I have delved into machine- learning methods, both for sediment characterization and source localization. I am fortunate to have colleagues who share experimental data with me, which facilitates the validation of my methods in real environments.
Describe your career path.
I was born in Athens, Greece. Often, when I was in elemen- tary school, I would get together with my best friend and we would put together electrical circuits from a set that had been given to my brother as a present. I then attended Pierce College, the high school of the American College of Greece. I had the opportunity there to be exposed to a rich curriculum in liberal arts, science and mathematics, lan- guages, and art. Math attracted me the most, and I decided early on that I wanted to do something with numbers.
As is often the case, I was told that girls are not made for math and that only made me more determined to pursue
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62 Acoustics Today • Spring 2021 | Volume 17, issue 1

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