Why does the frequency matter so much?

The mass law gives 6 dB per doubling of mass times frequency. Halving the frequency therefore doubles the mass needed to hold the same transmission loss. A 25 dB requirement needs about 1.7 lb/ft² at 500 Hz and about 6.7 at 125.

The required mass exceeds my structural capacity. Options?

Three real ones. Use a double-leaf partition with an air gap, treat the source so less area needs mass, or renegotiate the requirement now the physics is concrete.

Why use 33.5 rather than 28.5 in the formula?

Those are the field-incidence and normal-incidence constants. Real partitions are struck from all directions, and using 28.5 would overstate every barrier by about 5 dB, enough to turn a good treatment into a torn-out one.

Does two layers of one-pound vinyl equal two-pound vinyl?

Acoustically, roughly yes. Two limp layers in contact behave as one layer of the combined mass, worth about 6 dB and nothing more. To do better they need an air gap, which makes it a double-leaf design.

Acoustic, Noise, Vibration & NVH Products calculator

Acoustic Barrier Mass Loading Calculator

Work out how heavy a barrier must be to deliver a required noise reduction. Enter area, required transmission loss, design frequency and structural capacity; the page returns surface density, total mass and the margin.

What this calculator does

Turn a required transmission loss into the barrier surface density and total mass it demands, and check that mass against the structure.

Formula used

Required surface density = 10^((required TL + 33.5) ÷ 20) ÷ design frequency
Total added mass = required surface density × barrier area
Margin = structural capacity − required surface density
Surface density for 6 dB more = required surface density × 10^(6 ÷ 20) ≈ ×2
Best TL the structure allows = 20 × log10(capacity × frequency) − 33.5

Inputs explained

Barrier Area to Treat: Every surface in the transmission path, not only the source-facing one.
Required Transmission Loss: Single-frequency reduction the specification demands.
Design Frequency: Frequency the requirement applies at; the lowest one sets the mass.
Structural Capacity Available: Added dead load the structure can accept, from the structural engineer.

How to use the result

Best suited to converting a complaint into a barrier specification, checking whether a roof can carry the barrier, showing what six more decibels costs in mass.
Ignores the coincidence dip, where a real panel loses several decibels in a band. Ignores flanking around the barrier, which frequently governs the installed result. Not a structural assessment; it compares one number against an allowance somebody else supplies.

Common questions

Why does the frequency matter so much? The mass law gives 6 dB per doubling of mass times frequency. Halving the frequency therefore doubles the mass needed to hold the same transmission loss. A 25 dB requirement needs about 1.7 lb/ft² at 500 Hz and about 6.7 at 125.
The required mass exceeds my structural capacity. Options? Three real ones. Use a double-leaf partition with an air gap, treat the source so less area needs mass, or renegotiate the requirement now the physics is concrete.
Why use 33.5 rather than 28.5 in the formula? Those are the field-incidence and normal-incidence constants. Real partitions are struck from all directions, and using 28.5 would overstate every barrier by about 5 dB, enough to turn a good treatment into a torn-out one.
Does two layers of one-pound vinyl equal two-pound vinyl? Acoustically, roughly yes. Two limp layers in contact behave as one layer of the combined mass, worth about 6 dB and nothing more. To do better they need an air gap, which makes it a double-leaf design.

Last reviewed 2026-10-01.