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Презентация на тему Apartment acoustics. Analyzed using the acoustic diffusion equation

OverviewThe steady state sound pressure level distribution from a TV in a two-room apartment is computedThe simulation uses the Acoustic Diffusion Equation interfaceAn approximate expression for the direct sound is added in the living room
Apartment Acoustics Analyzed using the Acoustic Diffusion Equation#24311 OverviewThe steady state sound pressure level distribution from a TV in a Geometry and MeshThe geometry consists of a living room, a bedroom, and PhysicsThe simulation is driven by an energy flux assigned to the speaker Physics, cont.The simulation is solved for a flat band, i.e. with absorption Physics, cont.The acoustic diffusion equation does not include direct soundAssuming that the Results23 dB drop between the red dots (listening and sleeping positions)Sound pressure level (dB) Results, cont.The Schroeder frequencies for the bedroom and living room evaluate to
Слайды презентации

Слайд 2 Overview
The steady state sound pressure level distribution from

OverviewThe steady state sound pressure level distribution from a TV in

a TV in a two-room apartment is computed
The simulation

uses the Acoustic Diffusion Equation interface
An approximate expression for the direct sound is added in the living room

Слайд 3 Geometry and Mesh
The geometry consists of a living

Geometry and MeshThe geometry consists of a living room, a bedroom,

room, a bedroom, and some rudimentary furniture
The acoustic diffusion

equation does not have any strong demands on the mesh


Слайд 4 Physics
The simulation is driven by an energy flux

PhysicsThe simulation is driven by an energy flux assigned to the

assigned to the speaker fronts





Both rooms have their diffusion

coefficient calculated using the cubic room mean free path model:


Between the rooms, a room coupling condition applies a 10 dB transmission loss (TL) representing a door




 

c = speed of sound
V = room volume
S = area of walls, floor, ceiling


Слайд 5 Physics, cont.
The simulation is solved for a flat

Physics, cont.The simulation is solved for a flat band, i.e. with

band, i.e. with absorption coefficients considered independent of the

frequency
An absorption coefficient of 0.7 is applied to the soft surfaces and an absorption coefficient of 0.25 to the hard surfaces. Especially the latter is a little higher than typical, to compensate for the lack of carpets, curtains, etc.





For more realistic results, it is recommended that you modify the application to include different absorption coefficients for different materials and in different frequency bands


Soft surfaces


Слайд 6 Physics, cont.
The acoustic diffusion equation does not include

Physics, cont.The acoustic diffusion equation does not include direct soundAssuming that

direct sound
Assuming that the speakers send out sound isotropically

in a half-space, most of the living room is expected to experience a direct sound intensity from each speaker approximated by the expression corresponding to a squared pressure amplitude

The total sound pressure level then becomes

 

 

 

in the living room

in the bedroom

Pn = Power from speaker n
rn = distance to center of speaker n
Z0 = characteristic air impedance
pd = diffuse pressure
pref = 20⋅10-6 Pa

See also reference: A. Billon, J. Picaut, V. Valeau, and A. Sakout, “Acoustic Predictions in Industrial Spaces Using a Diffusion Model”, Advances in Acoustics and Vibration, Volume 2012 (2012).


Слайд 7 Results
23 dB drop between the red dots (listening

Results23 dB drop between the red dots (listening and sleeping positions)Sound pressure level (dB)

and sleeping positions)
Sound pressure level (dB)


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