IMPLEMENTATION AND EVALUATION OF DISPERSION-INVARIANT FEATURES FOR SIGNAL CLASSIFICATION Greg Okopal, M.S. University of Pittsburgh, 2007 When a sound wave interacts with an object, the acoustic energy may excite resonances in the object corresponding to its natural modes of vibration. The backscattered wave will then contain information which can be used to distinguish among different objects....

Effective dynamic properties of acoustic metamaterials made of multilayered flexible thin-plates with periodically attached mass-spring resonators are studied. By using the transfer matrix method, the thin-plate acoustic metamaterial under the plane wave incidence is characterized by a homogeneous effective medium with anisotropic mass density. An approximate analytic expression of effective ma...

BACKGROUND Models of honest advertisement predict that sexually selected calls should signal male quality. In most vertebrates, high quality males have larger body sizes that determine higher social status and in turn higher reproductive success. Previous research has emphasised the importance of vocal tract resonances or formant frequencies of calls as cues to body size in mammals. However, th...

Cognitive mechanisms for recognizing high quality sexual rivals should facilitate the economical allocation of mating effort. Women compete to attract male investment, and previous studies have shown that feminine voices are attractive to men. Here, we manipulated two sexually dimorphic acoustic parameters in women’s voices, fundamental frequency and formant dispersion, by the same perceptual a...

We study the propagation of sound in complex colloidal systems. By combining Biillouin scattering with ultrasonic techniques, we measure the dispersion in the acoustic propagation over three decades in frequency. Acoustic propagation is sensitive to the bulk compressibility of the medium, and probes new structural and dynamic properties of the colloidal system. We study two colloidal systems. T...

This work reports on theoretical and experimental study of zero-order as well as high-order symmetric and asymmetric modes of Lamb-wave resonators and delay line structures realized in single-crystalline GaN thin films. We investigate the phase velocity, dispersion characteristics, electromechanical coupling (kt), motional impedance (Rm) and Quality factor (Q) of different Lamb-wave modes (e.g....

The reconstruction of photoacoustic images typically neglects the effect of acoustic absorption on the measured time domain signals. Here, a method to compensate for acoustic absorption in photoacoustic tomography is described. The approach is based on time-reversal image reconstruction and an absorbing equation of state which separately accounts for acoustic absorption and dispersion following...

While usually negligible in standard optical fibers, the group velocity dispersion of acoustic waves may some cases play a significant role dynamics stimulated Brillouin scattering (SBS) propagation media with more complex structures, such as microstructured fibers. The usual three-wave coherent model SBS can be adapted to take perturbative into account, but slowly varying envelope approximatio...

Cognitive acoustic cues have an important role in shaping the phonological structure of language as a means to optimal communication. In this paper we introduced P-trac procedure in order to track dispersion of contrasts in different contexts in lexicon. The results of applying P-trac procedure to the case of dispersion of contrasts in preconsonantal contexts and in consonantal positions of CVC...