Calculateur de Perte par Transmission Sonore Gratuit
Calculez la perte par transmission sonore d'une paroi. Estimez l'isolation acoustique selon la masse et la fréquence.
Transmission Loss
32.70 dB
Transmission Loss vs Frequency
Formule
Mass Law for Sound Transmission Loss
The mass law gives the theoretical TL of a single homogeneous panel.
Formula
TL = 20 log10(f m) - 47.3 dB
Doubling the mass or frequency increases TL by about 6 dB. This is the field-incidence mass law, valid below the coincidence frequency.
Exemple Résolu
20 kg/m2 concrete panel at 500 Hz.
- 01TL = 20 log10(500 * 20) - 47.3
- 02TL = 20 log10(10000) - 47.3
- 03TL = 20 * 4 - 47.3
- 04TL = 80 - 47.3 = 32.7 dB
Questions Fréquentes
Why does the mass law fail at certain frequencies?
At the coincidence frequency, bending waves in the panel match the airborne sound wavelength, causing a dip in TL. This frequency depends on panel stiffness and thickness.
How can I exceed the mass law?
Use double-leaf constructions (two panels with an air gap), add damping, or use different-thickness panels to avoid common coincidence frequencies.
Is thicker always better?
Heavier is better within the mass-law regime. Very thick panels of the same material are also stiffer, which can lower the coincidence frequency and reduce TL at mid frequencies.
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