Hypotheses regarding exploitation of bubble acoustics by cetaceans

Abstract

Having evolved over tens of millions of years to cope with the underwater acoustic environment, cetaceans may have developed extraordinary techniques from which we could learn. This paper outlines some of the possible interactions, ranging from the exploitation of acoustics by humpback whales (Megaptera novaeangliae) in bubble nets to trap prey, to techniques by which coastal dolphins (e.g. of the genus Cephalorhynchus) could successfully echolocate in bubbly water (a hypothesis which has led to the development of a man-made sonar which can penetrate bubble clouds, and a range of possibilities for homeland security.

Clutter suppression and classification using twin inverted pulse sonar (TWIPS)

“…These include harbour protection, the detection of bubbles in marine sediments (Leighton & Robb 2008) and manufacturing (Yim & Leighton 2010). Biomedical applications, in addition to UCA studies, include monitoring biomedical shunts and participating in the current debate on distinguishing nonlinearly scattering bubbles from large, linearly scattering ones in tumour treatment using ultrasound (ter Haar 1995;Kennedy 2005;Rabkin et al 2006;Coussios et al 2007;Farny et al 2008;Leighton et al 2008c;McLaughlan et al in press). A twin inverted pulse radar might be used to distinguish between sediment (which scatters linearly), rusty metal (which predominantly scatters odd harmonics) and semiconductors (which scatter all harmonics), with application to the detection of improvised explosive devices and in-wall surveillance equipment.…”

“…For the monostatic deployments considered here, the bubbles to be suppressed or enhanced by nonlinearity must be close to the sonar source because the field emitted by the source decays geometrically with increasing range. However, if the bubbles are distant, bistatic arrangements can be used that place the source close to the potentially nonlinear scatterers, while the observer remains distant (Leighton et al 2008c).…”

“…Such schemes could be exploited by any radiation (Light Detection and Ranging (LIDAR), Magnetic Resonance Imaging (MRI), etc. ), which can be made to scatter nonlinearly by a relevant target with viable excitation amplitudes (Leighton et al 2008c).…”

Dolphin-Inspired Target Detection for Sonar and Radar

“…The implications of providing a type of sonar that can operate in bubbly shallow waters are clear. From the earliest days, however, we recognized that the equations governing the TWIPS and BiaPSS detection and classification schemes discussed in this paper were generic and not specifically linked to sonar, and as soon as we had evidence that TWIPS worked, we published the possibility that they might be used with lidar to detect combustion products, with MRI to discriminate between tissues, and with radar to detect covert electronics (covert bugging devices, and the threat of improvised explosive devices -IEDs -being particularly germane) (Leighton et al, 2007c;2008b). We experimentally tested the concept of TWIPR (Twin Inverted Pulse Radar) by emitting pairs of radar pulses, the second being identical to the first but having inverted phase (Fig.…”

Radar clutter suppression and target discrimination using twin inverted pulses

“…These results suggest that other pulse processing schemes, for example BiaPSS [6], would potentially also be operable with radar and with other electromagnetic radiations (MRI, LIDAR [1,4]). For TWIPR to work, the amplitude of the pulse incident on the target must be sufficiently high.…”