Identification of acoustic model parameters of porous materials


Defining the acoustic model parameters of porous noise control treatments is a critical part of the acoustical design process in a simulation software. FOAM-X allows you to identify these parameters from standard tests.

FOAM-X uses identification algorithms that works with acoustic data output from ASTM E1050 and ISO 10534-2 impedance tube tests or ASTM E2611 transmission tube tests to identify porous material parameters. From sound absorption coefficient or dynamic bulk modulus and dynamic bulk density, it calculates the main acoustic model parameters of open-cell porous materials: open porosity, static airflow resistivity, tortuosity, viscous and thermal characteristic lengths, thermal static permeability, Young’s modulus, Poisson’s ratio and damping loss factor.



  • FOAM-X software works with all standards ASTM E1050, ISO 10534-2, and ASTM 2611 impedance and transmission tube equipments (Direct Acoustic Test Method);

  • FOAM-X can characterize many different types of open-cell porous materials (foam, fiber, perforated plate, resistive screen, fabrics, etc.);

  • FOAM-X can also characterize each of the following frame type (rigid, limp, elastic);

  • FOAM-X allows you to extract:

    • Static airflow resistivity

    • Open porosity

    • Viscous characteristic length

    • Thermal characteristic length

    • Tortuosity

    • Thermal static permeability

    • Young’s modulus

    • Poisson’s ratio

    • Damping loss factor

  • FOAM-X has also a simulation and a sensitivity tool (analytical and numerical solver) taken into account of boundary conditions (clamped, slinding, air leaks);

  • FOAM-X has its own database to store the identified materials and compare them;

  • FOAM-X writes out characterization results in a compatible XML format with ESI Group VA One and NOVA.


Inverse Method


Additional Features

  • Use Direct Acoustic Test Method

    • To determine tortuosity and characteristic lengths, FOAM-X is more robust and accurate than ultrasonic test methods which may yield to 20-35% error;

    • Single test with more consistent results;

    • Tortuosity and characteristic lengths with error below than 10%.

  • Properties Identification

    • Mean and standard deviation of datasets;

    • Corrects room and tube conditions (temperature, barometric pressure and relative humidity);

    • User-defined auxiliary parameters: bulk density, resistivity (optional override), porosity (optional override) and tortuosity (optional override);

    • Material model for identification (rigid or limp frame);

    • Frequency range (min, max).

  • Display, Simulation and Sensitivity analysis

    • Validate parameters based on Biot’s poroelastic models and transfer matrix or finite element simulations against impedance tube measurements;

    • Plot overlay of prediction and test data:

      • Absorption, reflection or impedance

      • Transmission loss

      • Dynamic properties (characteristic impedance, wave number, effective density, effective bulk modulus)

      • Save (export)

    • Accurate hi-order axi-symmetrical finite element (axiFEM) solver to simulate effects of boundary conditions and acoustical leaks in impedance tubes;

    • Predict all acoustic properties under normal incidence plane wave: absorption coefficient, transmission loss, surface and characteristic impedance, complex wave number, dynamic effective density and bulk modulus;

    • Simulations account for:

      • Cavity (plenum), rigid, or anechoic terminations

      • Boundary conditions (clamping, slinding)

      • Rigid, limp and elastic frames

      • Thickness and diameter

      • Room conditions

      • Sensitivity to uncertainties

  • Database

    • Store your materials identified by FOAM-X or by your own method;

    • Search a material in function of different criteria (e.g. price, porosity, airflow resistivity, thickness, etc.);

    • Compare two materials.