What is simulated
In the ASTM E2611 configuration, the sample sits between an upstream and a downstream tube section, with two microphone positions on each side. From the sound field on both sides, the sample's 2×2 transfer matrix is obtained, and from it the transmission coefficient τ. Transmission loss is then
As with absorption, the result is for plane waves at normal incidence, within the same tube-diameter frequency limits.
Deliverables
- Normal-incidence transmission loss TL(f) in dB.
- Absorption α(f) and reflection R(f) for the same sample.
- CSV data, plots and a short report.
Typical uses
- Comparing panel, lattice or metamaterial designs that must block sound as well as absorb it.
- Checking how transmission loss changes with thickness, perforation or cell geometry before building prototypes.
Pricing
Transmission loss is an add-on of +$20 per sample on top of the per-sample price ($50 each for samples 1 to 9, $40 each from the tenth). Select "Absorption + transmission loss" on the quote form.
Accepted files and required inputs
- Geometry: STL, STEP, IGES, 3MF, OBJ, or a ZIP of these. Up to 95 MB per file and 10 files per request.
- Either the full sample as it would sit in the tube, or one periodic unit cell plus the sample thickness and diameter.
- Units of the CAD file (for example millimetres), so the geometry is scaled correctly.
- Backing condition: rigid backing, or the depth of any air gap behind the sample.
- Tube diameter and frequency range: Ø29 mm (about 500–6300 Hz), Ø100 mm (about 50–1600 Hz), or both stitched into one curve.
- Whether you also need transmission loss.
What normal-incidence TL is not
Normal-incidence transmission loss from a tube is not the same quantity as sound reduction measured between reverberant rooms for building elements, and it should not be quoted as a building-acoustics rating.
Simulation, not accredited testing. Results are a numerical simulation of the standard test configuration, not an accredited laboratory measurement. If you need a certified test report for product certification or building-code compliance, use the simulation to choose the design and then have the final design measured by an accredited laboratory.