Impedance tube — absorption & transmission loss

A Brüel & Kjær Type 4206-T impedance tube kit for characterising how materials interact with sound. It supports two standard measurements from the same bench:

Sound absorption (two-microphone transfer-function method, ISO 10534-2 / ASTM E1050)

• Measures a sample’s absorption coefficient, reflection coefficient, and normal acoustic impedance.
• Two tube sizes cover a wide band: the large tube (100 mm) for ~50 Hz–1.6 kHz and the small tube (29 mm) for ~500 Hz–6.4 kHz.
• A sliding sample-holder piston allows an adjustable air gap behind the sample.

Transmission loss (four-microphone transfer-matrix method, ASTM E2611)

• Measures how much sound a material blocks as it passes through, using the 4-microphone source-and-receiving-tube configuration.
• Useful for evaluating panels, barriers, and layered/absorptive materials.

Measurements are acquired with the lab’s Brüel & Kjær LAN-XI front end and an open-source analysis toolchain, so results are reproducible and licence-free.

Access for collaborators

Available for acoustic material testing — bring your samples and we’ll help with sample preparation, calibration, measurement, and analysis.