Sound Waves in Rooms

Abstract

Rev. Mod. Phys. 16, 69 (1944) j~D D to the last paragraph of Section 20 the following sentences and equation: For instance, f' or wave-lengths long compared to the thickness of material plus air backing, the wall impedance is approximately that of two equivalent circuit arms in parallel, the impedance of the two arms being r"L+(ipc'/MPL) and r"L+(i pc'/coL, B, ) Transverse waves suppressed .where 8 cos yl, Transverse waves allowed This corresponds approximately to the circuit in Fig. 8a. In the present instance it is somewhat more accurate to insert a resistance in both arms and to neglect the inductance. The third arm, corresponding to panel motion, will be discussed in the next section. Erratum: Surface Roughness and Sliding Friction J. J. BIKKRMAN [Rev. Mod. Phys. 16, 53 (1944)g W~N page 63, in the second paragraph in the left-hand column, (Section 1I, 6) should be (Sectioñ JJ, 2, b3).

Computational studies of steady-state sound field and reverberant sound decay in a system of two coupled rooms

“…Assume that a source term in the wave equation has the form −Q(r)cos(ωt), where Q(r) and ω are the volume source distribution and the sound frequency, and the acoustic pressure p(r, t) satisfies homogeneous initial conditions and the boundary condition (2). In this case the function describing time behaviour of the first mode (m, n = 0), the so-called Helmholtz mode that has an eigenfrequency equal to zero, is described by [24] P 00 (t) = Q 00 exp(−2r 00 t) ω 2 + 4r 2 00…”

“…geometrical theory [1], wave theory [2], ray-tracing techniques, and statistical or power flow methods [3]. Geometrical room acoustics at best applies to highly reverberant rooms whose characteristic dimensions are large compared to the wavelength.…”

Prediction of Reverberant Properties of Enclosures via a Method Employing a Modal Representation of the Room Impulse Response

“…In room acoustics, these methods yield the resonant modes of pressure vibrations in a room, and the pressure field in the room is expressed as a linear combination of the resonant modes (Meissner, 2010;Dance, Van Buuren, 2013). The most common among these methods are the normal mode analysis (Morse, Bolt, 1944), which is the oldest and simplest type of modal analysis, the classical modal analysis (Dowell, 1978) developed by using the Green's theorem, the asymptotic modal analysis (Kubota, Dowell, 1992), and the hybrid modal analysis (Xu, Sommerfeldt, 2010) that combines the free field Green's function and a modal expansion. Methods employing the modal expansion approach are more difficult to apply for rooms with complex shapes (Li, Cheng, 2004; Sum, Pan, 2006) but it fully describes the wave nature of a sound field such as degeneration of modes (Meissner, 2009a) and modal localization (Félix et al, 2007;Meissner, 2009b), as well as creation of energy vortices in the sound intensity field (Meissner, 2012;2015a).…”

Effects of sound radiation on Sabine absorption coefficient of modally-reactive panels

“…The behavior of the coefficient was then studied for different incident angles that correspond to individual acoustic modes of the enclosed sound field. When the sound field is diffuse, the absorption coefficient of the surface is known as statistical absorption coefficient (or random-incidence absorption coefficient), and it has also been derived analytically in terms of the acoustical impedance and investigated for different magnitudes and phases of the impedance [2,3]. In addition, a few numerical techniques were also developed for the estimation of the statistical absorption coefficient (e.g.…”