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 Institute of Applied & Computational Mathematics

R & D Activities

Ocean Bioacoustics

Cetaceans use sound for surveillance, communication and foraging. In particular, odondocetes (toothed whales), such as sperm whales and dolphins, are acoustically very active. Their sounds can be divided into two categories: tonal (voice-like) sounds of prolonged duration and changing frequency and broadband impulsive sounds of extremely short duration. Tonal sounds (e.g. whale songs, whistles) are associated more with social and communication activity. Impulsive sounds are used either in regular mode (clicks) as biosonar for detection, or in encoded form (codas) for communication.

Whistles and clicks produced by dolphins. The whistles are tonal sounds in the lower frequency range (less than 20 kHz). The clicks are short-duration broadband pulses (100-kHz bandwidth) in the ultrasound regime.

The activity of IACM's Wave Propagation Group in ocean bioacoustics began in 2001 (collaboration with A. Frantzis - PELAGOS Cetacean Research Institute), focusing on sounds by marine mammals, sperm whales and Cuvier's beaked whales, in particular. The motivation for studying sperm whales is the existence of a significant population along the Greek trench. As regards Cuvier's beaked whales, their massive stranding close to test sites of low frequency active sonars (LFAS) has stimulated interest about this species' acoustical behavior.

IACM contributions

IACM Wave Propagation Group uses its expertise on underwater acoustic propagation modelling and inverse problems and develops analysis tools to support acoustic behavioral studies of vocalizing cetaceans, with contributions in the following directions

  • Analysis and characterization of cetacean sounds
  • Methods for passive localization of vocalizing animals.
  • A. Frantzis, J. Goold, E. Skarsoulis, M. Taroudakis, V. Kandia, Clicks from Cuvier's beaked whales, Ziphius Cavirostris, Journal of the Acoustical Society of America, Vol. 112, pp. 34-37, 2002
  • E.K. Skarsoulis, A. Frantzis, M. Kalogerakis, Passive localization of pulsed sound sources using a 2-hydrophone array, 7th European Conf. on Underwater Acoustics, Delft, 2004.
  • E.K. Skarsoulis, A. Frantzis, M. Kalogerakis, Underwater acoustic localization of pulsed sources, Acoustics 2004, Thessaloniki, Sept. 2004.
  • E.K. Skarsoulis, M.A. Kalogerakis, Ray-theoretic localization of an impulsive source in a stratified ocean using two hydrophones, submitted to the Journal of the Acoustical Society of America, April 2005.

PELAGOS Cetacean Research Institute

ACCOBAMS - Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area

European Cetacean Society