| Section A | A index | 111-119 of 917 terms |
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acoustic impedance—The total reaction of a medium to sound transmission through it, represented by the complex ratio of the sound pressure to the effective flux, that is, particle velocity times surface area through the medium, expressed in acoustic ohms.
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acoustic intensity—The average acoustic power transported across a unit area, usually expressed in watts per square meter.
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acoustic lens—A system of disks or other devices to spread or converge sound waves in a manner analogous to the way an optical lens refracts light.
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acoustic ocean current meter—An instrument used to monitor currents by measuring the difference in travel time between each acoustic pulse transmitted in a direction opposite to the flow of a current, and the return pulse.
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acoustic rain gauge—An instrument designed to determine rainfall over lakes and oceans. A hydrophone is used to sense the sound signatures for each drop size as rain strikes a water surface. Since each sound signature is unique, it is possible to invert the underwater sound field to estimate the drop-size distribution within the rain. Selected moments of the drop-size distribution yield rainfall rate, rainfall accumulation, and other rainfall properties.
Nystuen, J. A., et al., 1996: A comparison of automatic rain gauges. J. Atmos. Oceanic. Technol., 13, 62–73.
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acoustic reflection profiling—A type of seismic profiling of the subbottom layers of the ocean floor by acoustic waves that reflect off the interfaces of the bottom layers.
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acoustic reflectivity—The relative reflectivity of a specific material, that is, the tendency to deflect sound energy in a specific medium rather than absorb it.
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acoustic refraction—The change in the direction of sound as it travels through a medium due to differences in physical and chemical characteristics of the medium.
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