Adaptive wave field synthesis with independent radiation mode control for active sound field reproduction: Theory

Abstract

Sound field reproduction finds applications in music or audio reproduction and experimental acoustics. For audio applications, sound field reproduction can be used to artificially reproduce the spatial character of natural hearing. The general objective is then to reproduce a sound field in a real reproduction environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. For classical WFS, the room response thus reduces the quality of the physical sound field reproduction. In this paper, adaptive wave field synthesis (AWFS) is analytically investigated as an adaptive sound field reproduction system combining WFS and active control with a limited number of reproduction error sensors to compensate the response of the listening environment. The primary point of this paper is the definition of AWFS. Therefore, the fundamental behavior of AWFS is illustrated by analytical considerations and simple free-field simulation results. As demonstrated, AWFS is fundamentally related to WFS and “Ambisonics.” The paper introduces independent adaptive control of sound field reproduction on the basis of radiation modes, via the singular value decomposition of the transfer impedance matrix. Possible practical independent control of radiation modes for AWFS is discussed.

Sound Field Synthesis with Distributed Modal Constraints

“…The initial driving functions are for an anechoic environment using a feedforward synthesis procedure. There are two examples of this approach based on WFS [23,24]. The microphones alone cannot identify the field.…”

“…Driving functions can be found numerically by satisfying pressure constraints at a set of points [22,20,23], abbreviated here as the PC method. In some cases accurate solutions can be found, however in general poor conditioning and numerical difficulties can degrade solutions.…”

SLAAP: Silencing Loud Alarms to Attenuate PTSD: Frequency- Selective Silencing Device for Digital Filtering of Alarm Sounds to Enhance ICU Patient Recovery

“…As that is achieved, wave ield synthesis (WFS), an open-loop technology, can be explored in concordance with environmental design. Speciically, adaptive wave ield synthesis, combining WFS and active control to reproduce the spatial character of natural hearing, will ameliorate concerns of patient dissociative subtypes of PTSD symptomatology [9].…”

Velocity controlled sound field reproduction by non-uniformly spaced loudspeakers

“…The approach has also been studied extensively in the context of the active control of sound and vibration. 4 These methods using multiple loudspeakers have been theoretically developed based on the assumption that the control area is surrounded by either continuously distributed sources, or at least uniformly distributed discrete sources in sufficient number to avoid the spatial aliasing determined by the high frequency limit to be controlled. Aside from the difficulties of positioning loudspeakers exactly, the ideal assumption of a uniform arrangement of multiple loudspeakers is clearly not met by the standard multi-channel formats such as 5.1, 7.1, 10.2 and 22.2 channel layouts proposed by international telecommunication union [9] although there have been several research studies that consider non-uniform standard layouts [10,11,12,13].…”

“…Several technical methods using multiple loudspeakers have been proposed for generating spatial audio experience for more people in a wider area. Wave Field Synthesis (WFS), which produces artificial wave fronts synthesized by multiple loudspeakers based on the Kirchhoff-Helmholtz integral, was developed in order to obtain the signal inputs to an array of multiple sound sources to reproduce the virtual sound field [3,4]. Ambisonics, which is another method used in multichannel audio (also referred to as a fullsphere surround sound technique), is based on a spherical harmonic analysis of the field to be reproduced, the spherical harmonics providing a means of describing a 3D sound field in terms of natural spatial basis functions [5,6].…”