2444, rue Bonin Sherbrooke, J1K 1C4, Canada

(819) 346-5666 info@mecanum.com

Impedance and Transmission Tube Using 4 Microphones


Mecanum’s 4 microphones impedance tubes are specifically designed to measure the main normal indicators of a wide range of acoustical materials. The method is based on ASTM E1050ISO 10534-2 and ASTM E2611 standards for the absorption coefficient (α), the reflection coefficient (R) and the surface impedance (Zs). All other parameters are determined using the 4 microphones technique (ASTM E2611) or the 3 microphones technique12.

Note: All 4 microphones tubes also comes with the 3 microphones technique, in other words, all the latest techniques and standards are gathered in this high-end equipment.


**   Large spacing between µ1 and µ2 (or µ3 and µ4) is essential for better results at low frequencies (as stated in ASTM E1050)


Material properties

➡ Normal incidence sound absorption coefficient (α)

➡ Normal incidence complex reflection coefficient (R)

➡ Normal surface impedance (Zs/Zair)

➡ Normal incidence sound transmission loss (TL)

➡ Characteristic impedance (Z/Zair)

➡ Wave number (k)

➡ Transfer matrix coefficients (Tij)

➡ Equivalent/effective dynamic density (ρeq)

➡ Equivalent/effective dynamic bulk modulus or compressibility (Keq)


Tube Internal Diameter Frequency Range
29 mm  200-6600 Hz
44.44 mm 100-4300 Hz
 100 mm  35-1900 Hz


TUBE-X is a user-friendly software that will simplify your measurement procedure. It will allow you to choose between the different measurement techniques. It’s also fully compatible with FOAM-X software that can extract non-acoustic parameters of porous materials using the inverse method with a 2, 3 or 4 microphones absorption measurement and indirect method using the 3 or 4 microphones measurement.


  • Every Mecanum impedance tube is supplied with grids (for samples with low mechanical strength) and rings (to avoid leaks).

Other Mecanum’s Related Products

➡ Grids and rings

 Verification and calibration samples

 Porous material slicer

 Circular cutter

 Resistive screen and fabric holder

 Enviro Weather station

 Three-microphone version upgrade