IACM Colloquium
Seminar title:
Calibration of an Underwater Acoustic Source and Data Analysis
Speakers:
Josse Van Messem and Kieran Warnier De Wailly
French Naval Academy (Ecole Navale)
Abstract:
The Lubell Labs LL9162T is an underwater acoustic transducer operating between 250 Hz and 20 kHz. After 25 years of service at IACM-FORTH, its electroacoustic performance needed to be reassessed, focusing on its transmitting voltage response (TVR), directivity, and source level (SL).
A hybrid methodology combined laboratory measurements at high frequencies (10–20 kHz) -using pulsed emissions and time windowing to limit reflections- with open-sea measurements at low frequencies (250 Hz–1 kHz). Low-frequency source levels were estimated using transmission loss modeling. The results indicate that the transducer remains broadly consistent with its original specifications. The low-frequency source levels agree with theoretical predictions, while the TVR closely matches reference values between 12 and 16 kHz. However, an efficiency loss of approximately 5 dB was observed near 10 kHz, along with reduced performance above 17 kHz and changes in directivity from 15 kHz.
In this talk the theoretical background along with experimental procedures will be presented and the results obtained will be discussed.
Short CVs:
Josse VAN MESSEM
He obtained his baccalaureate with specializations in mathematics and physics in 2022. He then attended a preparatory class during 2 years at Lycée Pierre de Fermat, focusing on mathematics and physics. In 2024, he enrolled at the French Naval Academy where he learned navigation, military skills and chose a specialization in wave and signals. Now, he has been completing a final-year internship at the IACM for the past three months.
Kieran WARNIER DE WAILLY
He obtained his baccalaureate with specializations in mathematics and physics in 2021. He then joined a military preparatory class during 3 years at Prytanee, focusing on mathematics and physics. In 2024, he enrolled at the French Naval Academy where he learned navigation, military skills and chose a specialization in wave and signals. Now, he has been completing a final-year internship at the IACM for the past three months.
Time, Date & Location:
12:00, November 9, 2026, Fotakis Room