Evanescentwave reproduction using linear array of loudspeakers

Abstract

An acoustic evanescent wave reproduction method is presented. Evanescent waves have faster distance attenuation. In most sound field reproduction approaches, the evanescent wave is a spatial aliasing component and is an undesirable wave field for reproducing a pure plane wave. However, because of its faster distance attenuation property, it does not affect these approaches. In this work, we attempt to reproduce only the evanescent wave. If only the evanescent wave is reproduced, it can be applied for a local area sound reproduction system that can localize a sound field around one specific location. The evanescent wave reproduction system is constructed by using a linear loudspeaker array and digital filters. Computer simulation results showed that our method achieves faster distance attenuation than a simple sound source.Index Terms-evanescent wave, fast distance attenuation, local area sound reproduction, linear loudspeaker array, digital filter

Bounded inhomogeneous wave profiles for increased surface wave excitation efficiency at fluid–solid interfaces

“…The results presented here, which demonstrate that an optimal value of the incident wave decay rate can be identified with incidence near the Rayleigh angle, may prove useful for non-contact excitation in applications such as nondestructive testing 1,2,[4][5][6] and medical ultrasound imaging. 7,8 Moreover, these waveforms may be generated in practice by sound field reproduction techniques with phased arrays of sources, 29,[37][38][39] or by other approaches, 27,28,31,40 though the distortion of the profile over nonzero standoff distances would have to be carefully controlled in such an implementation (see also the Appendix). The generation of bounded inhomogeneous waves of the type considered in this work, in particular, was investigated by Declercq and Leroy, 26 and it was noted that a reasonable approximation may be achievable in the near field.…”

Efficient implementation of the spectral division method for arbitrary virtual sound fields

“…4(a). The synthesis of purely evanescent fields is feasible [12]. In order to suppress virtual evanescent components we setD(kx, ω) = 0∀ |kx| > ω c in (5) [9].…”

Localized sound reproduction using circular loudspeaker array based on acoustic evanescent wave

“…In our work, we reproduced pure evanescent waves at an audio frequency band. Previously, we used a linear loudspeaker array to reproduce an acoustic evanescent wave [10]. However, since our previous method using linear array requires a line source of infinite length in principle, a large number of loudspeakers are needed to realize sufficiently fast distance attenuation.…”