Experimental studies of passive correlation tomography of incoherent acoustic sources in the megahertz frequency band

Thermal acoustic radiation from multilamellar vesicles in lipid phase transition

“…The measurements were carried out in a thermostat tank (43 cm × 43 cm × 15 cm) filled with water. Mercury and electronic thermometers were used to monitor the temperature of the tank to a precision of 0.2 K. The TAR measurements were performed using the acoustothermometer constructed by Mirgorodskij et al (2006). It consisted of a piezotransducer and a high-frequency amplifier.…”

Retrieval of Green’s functions of elastic waves from thermal fluctuations of fluid-solid systems

“…[21][22][23] Promising applications of ambient noise cross-correlation to passive remote sensing have been proposed in underwater acoustics, [24][25][26][27][28][29] mechanical and civil engineering, [30][31][32][33] and medical acoustics. 34,35 Theoretically, the relation between cross-correlation of random fields in a stationary medium and the deterministic acoustic Green's function has been established using normal modes of a closed system, 7-9 time-reversal arguments, 36,37 stationary phase analysis, 26,[38][39][40] or reciprocity considerations; 6,[40][41][42][43] for recent reviews see Weaver and Lobkis 44 and Gouédard et al 16 Extension of this work to arbitrary inhomogeneous moving fluids showed that the crosscorrelation of an acoustic field due to random sources distributed on a surface gives a combination of acoustic Green's functions, which describe sound propagation in opposite directions between the two points, and contains information necessary to characterize both sound speed and flow velocity. 40 Similar results, but for a fluid with slow and weakly varying currents, were independently obtained in Refs.…”

“…Thermal noise often dominates the noise field at sufficiently high frequencies. 7,8,34,[47][48][49][50][51][52] Measurements of intensity and correlation properties of thermal radiation underlie acoustic brightness thermometry and thermoacoustic tomography, which have important biomedical applications. 48,51,53,54 In this paper, we apply the fluctuation-dissipation 3,55 and flow reversal 56-58 theorems ͑FRTs͒ to calculate statistical moments of thermal fluctuations in rather general fluid-solid systems, which comprise arbitrary inhomogeneous fluid flow and an anisotropic solid.…”

On the possibility of using acoustic reverberation for remote sensing of ocean dynamics

“…Similar approaches are being developed in medical diagnostics. The latter approaches are based on thermal noises [33][34][35] and natural vibrations of muscles [36]. The possibility of passive acoustic tomography of the ocean by means of noise interferometry was first experimentally demon strated in recent publication [37].…”