890 research outputs found
Implementation and Perceptual Evaluation of a Simulation Method for Coupled Rooms in Higher Order Ambisonics
A fast and perceptively plausible method for rendering acoustic scenarios with moving sources and moving listeners is presented. The method is principally suited for application in dynamic and interactive evaluation environments (e.g., for hearing aid development), psycho-physics with adaptively changing the spatial configuration, or simulation and computer games. The simulation distinguishes between the direct sound, sound reflected and diffracted by objects of limited size, diffuse sound surrounding the listener, e.g., diffuse background sounds and diffuse reverberation, and ’radiating holes’ for simulation of coupled adjacent rooms. Instead of providing its own simulation of room reverberation, the proposed simulation method generates appropriate output signals for external room reverberation simulators (e.g., see contribution by Wendt et al.). The output of such room reverberation simulators is then taken either as diffuse surrounding sound if the listener position is within the simulated room, or as input into a ’radiating hole’, if the listener is in an adjacent room. Subjective evaluations are performed by comparing measured and synthesized transitions between coupled rooms.DFG, FOR 1732, Individualisierte Hörakustik: Modelle, Algorithmen und Systeme für die Sicherstellung der akustischen Wahrnehmung für alle in allen Situatione
Efficient Synthesis of Room Acoustics via Scattering Delay Networks
An acoustic reverberator consisting of a network of delay lines connected via
scattering junctions is proposed. All parameters of the reverberator are
derived from physical properties of the enclosure it simulates. It allows for
simulation of unequal and frequency-dependent wall absorption, as well as
directional sources and microphones. The reverberator renders the first-order
reflections exactly, while making progressively coarser approximations of
higher-order reflections. The rate of energy decay is close to that obtained
with the image method (IM) and consistent with the predictions of Sabine and
Eyring equations. The time evolution of the normalized echo density, which was
previously shown to be correlated with the perceived texture of reverberation,
is also close to that of IM. However, its computational complexity is one to
two orders of magnitude lower, comparable to the computational complexity of a
feedback delay network (FDN), and its memory requirements are negligible
Computationally-efficient and perceptually-motivated rendering of diffuse reflections in room acoustics simulation
Geometrical acoustics is well suited for simulating room reverberation in
interactive real-time applications. While the image source model (ISM) is
exceptionally fast, the restriction to specular reflections impacts its
perceptual plausibility. To account for diffuse late reverberation, hybrid
approaches have been proposed, e.g., using a feedback delay network (FDN) in
combination with the ISM. Here, a computationally-efficient, digital-filter
approach is suggested to account for effects of non-specular reflections in the
ISM and to couple scattered sound into a diffuse reverberation model using a
spatially rendered FDN. Depending on the scattering coefficient of a room
boundary, energy of each image source is split into a specular and a scattered
part which is added to the diffuse sound field. Temporal effects as observed
for an infinite ideal diffuse (Lambertian) reflector are simulated using
cascaded all-pass filters. Effects of scattering and multiple (inter-)
reflections caused by larger geometric disturbances at walls and by objects in
the room are accounted for in a highly simplified manner. Using a single
parameter to quantify deviations from an empty shoebox room, each reflection is
temporally smeared using cascaded all-pass filters. The proposed method was
perceptually evaluated against dummy head recordings of real rooms.Comment: This work has been submitted to Forum Acusticum 2023 for publicatio
The modeling of diffuse boundaries in the 2-D digital waveguide mesh
The digital waveguide mesh can be used to simulate the propagation of sound waves in an acoustic system. The accurate simulation of the acoustic characteristics of boundaries within such a system is an important part of the model. One significant property of an acoustic boundary is its diffusivity. Previous approaches to simulating diffuse boundaries in a digital waveguide mesh are effective but exhibit limitations and have not been analyzed in detail. An improved technique is presented here that simulates diffusion at boundaries and offers a high degree of control and consistency. This technique works by rotating wavefronts as they pass through a special diffusing layer adjacent to the boundary. The waves are rotated randomly according to a chosen probability function and the model is lossless. This diffusion model is analyzed in detail, and its diffusivity is quantified in the form of frequency dependent diffusion coefficients. The approach used to measuring boundary diffusion is described here in detail for the 2-D digital waveguide mesh and can readily be extended for the 3-D case
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