AcouS STIFF Software
Software for predicting the sound reduction index
Presentation of AcouS STIFF® acoustic software (Acoustic Software Sound Transmission Index Full Forecast)
The sound reduction index of a wall can be measured in a laboratory specially designed for this purpose (decoupling of sending and receiving cells, shapes and sizes of cells, ....).
However the sound reduction index of a wall depends on a very large number of parameters. One naturally thinks of the thickness, or density of constituent materials, but particularly variable settings from one application to another, such as length and width of the panels are also of great importance, as evidenced by the following figure :
R as a function of embedding dimensions of the glazing
Under these conditions, the number of walls to be tested is infinite and a uniquely experimental approach, by the time and cost it represents, can not suffice.
Predicting then appears as an essential complementary approach.
Both approaches, laboratory measurement and calculation of estimates, far from being exclusive are complementary and necessary to one and the other : the experimental approach can be considered only as the number of cases to be tested, but the models simulation to be validated should be on individual cases properly chosen, of a comparison with experimental values.
AcouS STIFF® acoustic software is a simulation tool for calculations of sound reduction index.
Areas of application of the software
Acous STIFF® acoustic software is a simple and adapted tool that allows you to :

The results are presented as graphs and /or tables showing the overall values in accordance with ISO7171, NF S 31051 and ASTM E 413.
Defining the types of walls calculable using AcouS STIFF®
AcouS STIFF® acoustic software can perform calculations of forecast reduction index of the following types of walls :

In addition, one can perform the following operations on the sound reduction indexes :
 arithmetic sum of up to ten sound reduction indices,
 difference (Delta) between two indices of acoustic attenuation,
 heterogeneous walls composed of more than ten different wall elements.
The different types of bonds
We distinguish different mechanical connections including:
 point : an even distribution of tie points, expressed in dots per square meter,
 linear : parallel beam type link lines, this distribution is expressed by the spacing from line to line in meters,
 surface : the surface of the intermediate material is the mechanical connection between the external cladding. Only the uncoupling factor FD to be informed,
 device : it is only the foundation of the wall which forms the mechanical connection between the external cladding. The user has the choice of selecting 1 to 4 sides of the wall with a factor of uncoupling FD different for each side if desired. For each side, the connection device is in meters. Only the sides whose length and detaching factor FD are shown will be taken into account in the calculation.
For the same wall, there may be several types of association between the external cladding..