Acoustical scattering by multilayer spherical elastic scatterer containing electrorheological layer

Abstract

A computational procedure for analyzing acoustical scattering by multilayer concentric spherical scatterers having an arbitrary mixture of acoustic and elastic materials is proposed. The procedure is then used to analyze the scattering by a spherical scatterer consisting of a solid shell and a solid core encasing an electrorheological (ER) fluid layer, and the tunability in the scattering characteristics afforded by the ER layer is explored numerically. Tunable scatterers with two different ER fluids are analyzed. One, corn starch in peanut oil, shows that a significant increase in scattering cross-section is possible in moderate frequencies. Another, fine poly-methyl methacrylate (PMMA) beads in dodecane, shows only slight change in scattering cross-sections overall. But, when the shell is thin, a noticeable local resonance peak can appear near ka=1, and this resonance can be turned on or off by the external electric field.

Preferences for Very Low and Very High Voice Pitch in Humans

“…These data also support previous findings that men prefer high-pitched women's voices to low-pitched women's voices [26], [53], [56], [57], [58], [59], [60]. Such preferences for very high voice pitch among women may be adaptive as voice pitch is indicative of potential reproductive health [61] and youth.…”

“…Thus, the differences in JNDs between tasks cannot be attributed to pitch discrimination having an objectively correct answer while social attributions do not. The perceptual link between pitch and attractiveness may be less tightly coupled because vocal attractiveness is based on several vocal parameters besides pitch, including formant frequencies [17], [23], [53], [73], intonation [74], and word content [23], [40]. Regardless of the proximate mechanism, poor mate-choice decisions can be costly for both men and women [75], and thus it may be functionally adaptive for JNDs in attractiveness to be relatively larger than JNDs for pitch discrimination.…”

“…Four men and four women were asked to pick the voice with the higher pitch [47]. Several previous studies have assessed JNDs in pitch for vowel sounds [45], [46], [52], [53].…”

Generalized theory of resonance excitation by sound scattering from an elastic spherical shell in a nonviscous fluid

“…Moreover, the gTrs method can be applied to investigate the scattering of any beam of arbitrary shape that satisfies the source-free Helmholtz equation. Furthermore, the method can be readily adapted to viscoelastic spherical shells [56], layered spheres [57]- [59], layered shells [60], or multilayered spheres/shells [7]- [10]. additionally, this investigation would potentially be useful in evaluating the off-axial acoustic radiation force [34], [35] and torque [36], [37] on shells.…”

“…Exact solutions in the form of infinite series expansion were obtained using the resonance scattering formalism [2], [3] for spheres [4], shells [5], coated spheres and shells [6], and other formalisms for a multilayered spherical scatterer [7]- [10].…”