Underwater tunable organ-pipe sound source

Morozov, Andrey K.; Webb, Douglas C.

doi:10.1121/1.2751268

Cited by 23 publications

(4 citation statements)

References 19 publications

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“…Hydroacoustics, Inc., HLF-5 sources with a center frequency of 250 Hz ͑Munk et al, 1995͒ were located at about 750-m depth, approximately on the sound-channel axis. Webb Research Corporation ͑WRC͒ swept-frequency sources with a center frequency of 275 Hz ͑Morozov and Webb, 2003Webb, , 2007Webb et al, 2002͒ were located at about 3000-m depth, slightly above the estimated surface conjugate depth ͑Table I͒.…”

Section: Methodsmentioning

confidence: 99%

The vertical structure of shadow-zone arrivals at long range in the ocean

Uffelen

Worcester

Dzieciuch

et al. 2009

The Journal of the Acoustical Society of America

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Multimegameter-range acoustic data obtained by bottom-mounted receivers show significant acoustic energy penetrating several hundred meters into geometric shadow zones below cusps (caustics) of timefronts computed using climatological databases [B. D. Dushaw et al., IEEE J. Ocean. Eng. 24, 202-214 (1999)]. This penetration is much larger than predicted by diffraction theory. Because these receivers are horizontal arrays, they do not provide information on the vertical structure of the shadow-zone arrivals. Acoustic data from two vertical line array receivers deployed in close proximity in the North Pacific Ocean, together virtually spanning the water column, show the vertical structure of the shadow-zone arrivals for transmissions from broadband 250-Hz sources moored at the sound-channel axis (750 m) and slightly above the surface conjugate depth (3000 m) at ranges of 500 and 1000 km. Comparisons to parabolic equation simulations for sound-speed fields that do not include significant internal-wave variability show that early branches of the measured timefronts consistently penetrate as much as 500-800 m deeper into the water column than predicted. Subsequent parabolic equation simulations incorporating sound-speed fluctuations consistent with the Garrett-Munk internal-wave spectrum at full strength accurately predict the observed energy level to within 3-4-dB rms over the depth range of the shadow-zone arrivals.

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Section: Methodsmentioning

confidence: 99%

The vertical structure of shadow-zone arrivals at long range in the ocean

Uffelen

Worcester

Dzieciuch

et al. 2009

The Journal of the Acoustical Society of America

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“…The FAM Research opens an acoustic window at the water-air interface for acoustic transmission, which might enable various applications that are infeasible so far. For example, it allows to characterize the underwater sound with airborne sound sensoring systems [10], so that the special underwater acoustic devices could become needless [42]. By using FAMs, airborne sound systems can simultaneously detect the sound both from water and air.…”

Section: Discussionmentioning

confidence: 99%

Tunable Fluid-Type Metasurface for Wide-Angle and Multifrequency Water-Air Acoustic Transmission

et al. 2021

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Efficient acoustic communication across the water-air interface remains a great challenge owing to the extreme acoustic impedance mismatch. Few present acoustic metamaterials can be constructed on the free air-water interface for enhancing the acoustic transmission because of the interface instability. Previous strategies overcoming this difficulty were limited in practical usage, as well as the wide-angle and multifrequency acoustic transmission. Here, we report a simple and practical way to obtain the wide-angle and multifrequency water-air acoustic transmission with a tunable fluid-type acoustic metasurface (FAM). The FAM has a transmission enhancement of acoustic energy over 200 times, with a thickness less than the wavelength in water by three orders of magnitude. The FAM can work at an almost arbitrary water-to-air incident angle, and the operating frequencies can be flexibly adjusted. Multifrequency transmissions can be obtained with multilayer FAMs. In experiments, the FAM is demonstrated to be stable enough for practical applications and has the transmission enhancement of over 20 dB for wide frequencies. The transmission enhancement of music signal across the water-air interface was performed to demonstrate the applications in acoustic communications. The FAM will benefit various applications in hydroacoustics and oceanography.

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“…1). These subsurface moorings each supported a swept-frequency acoustic source (Webb et al, 2002;Morozov and Webb, 2007) with a frequency range of approximately 200-300 Hz, although the frequency characteristics varied from source to source ( Table I). The sources were moored at a nominal depth of 1050 m, approximately the depth of the sound channel axis.…”

Section: A Moored Tomography Experimentsmentioning

confidence: 99%

Estimating uncertainty in subsurface glider position using transmissions from fixed acoustic tomography sources

Uffelen¹,

Nosal²,

Howe³

et al. 2013

The Journal of the Acoustical Society of America

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Four acoustic Seagliders were deployed in the Philippine Sea November 2010 to April 2011 in the vicinity of an acoustic tomography array. The gliders recorded over 2000 broadband transmissions at ranges up to 700 km from moored acoustic sources as they transited between mooring sites. The precision of glider positioning at the time of acoustic reception is important to resolve the fundamental ambiguity between position and sound speed. The Seagliders utilized GPS at the surface and a kinematic model below for positioning. The gliders were typically underwater for about 6.4 h, diving to depths of 1000 m and traveling on average 3.6 km during a dive. Measured acoustic arrival peaks were unambiguously associated with predicted ray arrivals. Statistics of travel-time offsets between received arrivals and acoustic predictions were used to estimate range uncertainty. Range (travel time) uncertainty between the source and the glider position from the kinematic model is estimated to be 639 m (426 ms) rms. Least-squares solutions for glider position estimated from acoustically derived ranges from 5 sources differed by 914 m rms from modeled positions, with estimated uncertainty of 106 m rms in horizontal position. Error analysis included 70 ms rms of uncertainty due to oceanic sound-speed variability.

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Underwater tunable organ-pipe sound source

Cited by 23 publications

References 19 publications

The vertical structure of shadow-zone arrivals at long range in the ocean

The vertical structure of shadow-zone arrivals at long range in the ocean

Tunable Fluid-Type Metasurface for Wide-Angle and Multifrequency Water-Air Acoustic Transmission

Estimating uncertainty in subsurface glider position using transmissions from fixed acoustic tomography sources

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