Acoustic characterization of panel materials under simulated ocean conditions using a parametric array source

Abstract

A technique for evaluating the underwater acoustic performance of panels under simulated ocean conditions in a laboratory test facility is described. The method uses a parametric array as a source of sound within a test vessel capable of simulating ocean depths down to 700 m and water temperatures from 2 to 35 degrees C. The reflection loss and transmission loss of the test panel may be determined at frequencies from a few kilohertz to 50 kHz. The use of the parametric array enables wideband measurements to be undertaken with short-duration pulses and reduces the effects of diffraction from the panel edges. An acoustic filter is used to truncate the array in order to provide a source-free measurement region and to simplify the measurement process. The difficulties of establishing a parametric array in the confined space of the vessel are outlined, and the experimental procedures adopted are described. The techniques were validated by undertaking measurements on two test objects that have predictable behavior. The potential of the technique is also illustrated with experimental results for test panels for hydrostatic pressures up to 2.8 MPa. An extensive discussion of the measurement limitations is included.

Realization of an omnidirectional source of sound using parametric loudspeakers

“…For instance, in the field of active noise control PAA could avoid to a certain extent the problem of sound pressure increase beyond target quiet zone areas. 15,16 PAA beams have also been used to characterize the acoustic performance of materials [17][18][19] and both experimental, 20 as well as computational, 21 fundamental research are still very active. An informative first approach to parametric loudspeakers can be found in Ref.…”

Parametric Acoustic Array and Its Application in Underwater Acoustic Engineering

“…The most mature application of the PAA is the sub-bottom profiler [52][53][54]. Chirp sub-bottom profiler is widely used in the field of traditional acoustic detection [55,56], because Chirp sonar transmits LFM signals with broad bandwidth which carry a lot of information about the submarine stratum.…”

Experimental Study of a Broadband Parametric Acoustic Array for Sub‐Bottom Profiling in Shallow Water

“…Because it offers a low-frequency sound source with a narrow beam and no sidelobes, the technology has been used in subbottom profiling [5], industrial flaw detection [6], medical examination [7], biological detection [8], target tracking [9], and underwater acoustic communication [10,11]. However, its most mature application in underwater acoustics is still the sub-bottom profiler [12][13][14]. To satisfy measurement requirements at different depths, a single-frequency difference frequency signal is generally used in current parametric array sonar systems, and the original frequency is relatively low.…”