Mathematically trivial control of sound using a parametric beam focusing source

Abstract

By exploiting a case regarded as trivial, this paper presents global active noise control using a parametric beam focusing source (PBFS). As with a dipole model, one is used for a primary sound source and the other for a control sound source, the control effect for minimizing a total acoustic power depends on the distance between the two. When the distance becomes zero, the total acoustic power becomes null, hence nothing less than a trivial case. Because of the constraints in practice, there exist difficulties in placing a control source close enough to a primary source. However, by projecting a sound beam of a parametric array loudspeaker onto the target sound source (primary source), a virtual sound source may be created on the target sound source, thereby enabling the collocation of the sources. In order to further ensure feasibility of the trivial case, a PBFS is then introduced in an effort to meet the size of the two sources. Reflected sound wave of the PBFS, which is tantamount to the virtual sound source output, aims to suppress the primary sound. Finally, a numerical analysis as well as an experiment is conducted, verifying the validity of the proposed methodology.

Recent advances on active noise control: open issues and innovative applications

“…These unique characteristics of parametric loudspeakers allow for noise control to be confined within the directional beamwidth of the parametric loudspeakers. A comparison of noise control performance based on the sound pressure distribution between an omnidirectional voice coil loudspeaker and a directional parametric loudspeaker is conducted in [256].…”

Construction of an Omnidirectional Parametric Loudspeaker Consisting in a Spherical Distribution of Ultrasound Transducers

“…It was reported in [33] that, for planar PLAs, the convolution model better agrees with experimental results than previous models. A short while ago, the model has been extended to deal with PLAs set on curved surfaces [26], which could prove useful to analytically model the performance of several non-conventional PLA devices [21,23,24]. In particular, the generalized convolution model in [26] has been used as a guidance for designing the OPL prototype presented in this work.…”

“…In [21], for example, a flared horn was connected to an array of PZTs to enhance its directivity and intensity (see [22] for an analytical model of that device). A parametric beam focusing source was proposed in [23] which involved distributions of PZTs placed on a cylindrical shell (see also [24]). However, it was not until the work in [25] that it was first proposed to exploit the PAA to generate omnidirectional sound fields instead of focused ones.…”

Product directivity models for parametric loudspeakers

“…One application of steerable parametric loudspeakers that was implemented by Tanaka 12,13 is an active noise control system with a steerable beam control. In this system, a compact transducer array was fabricated with reduced spacing to suppress grating lobes to obtain a controllable directivity.…”