We propose a method of detecting a reflective layer in a layered random medium using the time reversal of an acoustic wave. Comparing the refocused signal with the original probing pulse enables us to detect a change it the medium’s acoustic properties. The depth of the reflector is pinpointed even in the absence of a direct coherent reflection. We present experimental results validating the pr...

The paper presents our recent work on the acoustic and physiological feature analysis of affective speech. An affective speech corpus is first built up. It contains passages read in neutral state and ten typical affective states selected in Pleasure Arousal Dominance (PAD) space. Physiological data, including electrocardiogram, respiration, electro dermal data, and finger pulse, are also collec...

We have used pulse time-of-flight techniques to examine the phonon emission from an optically excited GaAs/AlAs superlattice structure. For laser excitation wavelengths shorter than 767 nm ~the energy of E1HH1 transition!, we detect a significant longitudinal acoustic phonon component directed in a narrow beam normal to the structure. Under identical excitation conditions, generation of coheren...

We present here two diffractive acoustic lenses with subwavelength thickness, planar profile, and broad operation bandwidth. Tapered labyrinthine unit cells with their inherently broadband effective material properties are exploited in our design. Both the measured and the simulated results are showcased to demonstrate the lensing effect over more than 40% of the central frequency. The focusing...