Development of the Effective Underwater Speaker Sound Modulated by Audible Sound Frequency Range of Large Cetaceans for Avoidance with Ship Collision

• Main Authors: Hiroko Yamada, Nozomi Kobayashi, Tatsunori Nakashima, Hidehiro Kato
• Format: Article
• Language: English
• Published: Gdynia Maritime University 2015-06-01
• Series: TransNav: International Journal on Marine Navigation and Safety of Sea Transportation
• Subjects: Cetaceans; Underwater Speaker (UWS); Underwater Speaker Sound; Audible Sound Frequency Range; Hydrofoils; Hydroacoustics; Avoidance with Ship Collision; Large Cetaceans
• Online Access: http://www.transnav.eu/files/Development of the Effective Underwater Speaker Sound Modulated by Audible Sound Frequency Range of Large Cetaceans for Avoidance with Ship Collision,575.pdf

The underwater speaker (UWS) has been installed on high speed vessels; hydrofoils (HF) with low-noise during their cruises, to avoid sudden collisions with large cetaceans, while its performance has remained uncertain because of the problem in quality of the produced sound. Thus, we developed a sound source for the UWS by modulating the sound based on the audible range of major large cetaceans so as to increase its utilities. To investigate the audible sound frequency range of cetacean, we tried two procedures, (1) indirect-estimation from relationship between cetaceans audibility and vocalization, and (2) indirect-estimation from measurements on the cochlear basal membrane. We also synthesized the two new sound sources which we can potentially expect an avoidance with large cetaceans. Through several field experiments with deploy the new sounds we reached a tentative conclusion that the new sound was effective in terms of inducing the cetaceans' avoidance reaction and would be also expected to be applied to other low-noise vessels.