TL CALCULATOR

Calculate sound transmission loss for single and double-wall panel constructions.

Single Wall Panel

Material

Thickness (mm)

Surface Mass:

8.10 kg/m²

Critical Freq (f_c):

4008 Hz

TL @ 500 Hz:

24.8 dB

TL @ Coincidence:

15.9 dB

Double Wall Construction

Panel 1 uses the single wall settings. Configure Panel 2 and air gap below.

Panel 2 Material

Panel 2 Thickness (mm)

Air Gap (mm)

Total Surface Mass:

16.20 kg/m²

Mass-Air-Mass f₀:

133.4 Hz

Air Gap:

50.0 mm

Above f₀, double walls provide ~12 dB/octave improvement vs. 6 dB/octave for single walls.

Transmission Loss vs. Frequency

Blue: Single wall with coincidence dip at f_c = 4008 Hz

Green: Double wall with mass-air-mass resonance at f₀ = 133.4 Hz

Dashed: Ideal mass law (6 dB/octave)

Material Properties Reference

Material	E (GPa)	ρ (kg/m³)	η	f_c×h (Hz·mm)
Steel	200	7850	0.001	12298
Aluminum	70	2700	0.001	12025
Glass	70	2500	0.01	11958
Concrete	30	2400	0.03	17975
Plywood	12	600	0.02	13836
Gypsum Board	2.5	800	0.015	35002
Acrylic (PMMA)	3.2	1190	0.03	36748

Design Guidelines

Mass Law: Doubling mass or frequency adds +6 dB TL. Field incidence reduces TL by ~5 dB vs. normal incidence.

Coincidence: Keep f_c above frequency range of interest, or add damping (η > 0.1) to mitigate the dip.

Double Wall: Maximize air gap to lower f₀. Add absorption in cavity to further improve TL. Avoid structural bridges between panels.