Acoustic nonlinear imaging has brought about significant improvements in image quality by taking advantage of the nonlinear components. This paper reviews works on acoustic nonlinear imaging for biological tissues in our Laboratory, including acoustic nonlinearity parameter B/A imaging, tissue harmonic imaging by using the multi-phase-coded-pulse technique and super harmonic imaging. Theoretica...

Using a picosecond pump-probe ultrasonic technique, we study the propagation of high-amplitude, laser-generated longitudinal coherent acoustic pulses in the viscoelastic fragile glass former DC704. We observe an increase of almost 10% in acoustic pulse propagation speed at the highest optical pump fluence which is a result of the supersonic nature of nonlinear propagation in the viscous medium....

Acoustic model parameter estimation is hampered by a lack of data. To reduce the number of parameters to be estimated, we propose sub-GMM modelling, which constrains the acoustic models to a lowdimensional manifold embedded in the space of Gaussian mixture weights. The manifold model is obtained through non-negative matrix factorization with sparsity constraints. Our preliminary monolingual exp...

This work reports on the determination of the acoustic nonlinearity parameter, B/A, from measured sound speed data, in Fluorinert FC-43 at temperatures up to 381 K and pressures up to 13.8 MPa using the thermodynamic method. Sound speed was measured using Swept Frequency Acoustic Interferometry at 11 pressures between ambient and 13.8 MPa along 6 isotherms between ambient and 381 K. Second-orde...

I.I.T. Bombay, in collaboration with C.R.L., B.E.L., is working on developing a speech codec to provide communication quality speech at low bit rates. The codec is required to be robust to acoustic background noise and to channel errors. A sinusoidal coder based on the MBE (Multiband Excitation) model has been adopted as the basic speech representation due to its compact parameter set and the r...

ABSTRACT The prediction of underwater acoustic propagation is important strategically and tactically in undersea warfare as it is a critical parameter in determining detection range. In the relatively shallow waters of the continental shelves the acoustic properties of the seabed become the dominant factor but there are only a few locations where the relevant properties have been adequately det...