This simulator puts a loudspeaker on one side of a limp-mass partition and a measurement point on the other. Change frequency, surface mass and the open leakage area fraction to see solid-sheet loss, composite loss, transmitted level and the share of transmitted energy carried by the leak.
• A 3D wall with a source-side loudspeaker, a moving limp-mass partition, a small open service penetration and a receiving-side measurement position. • Sliders for incident frequency, surface mass, open leakage area fraction and incident level. • Five readouts: solid-sheet loss, composite loss, transmitted level, transmitted power fraction and leak share of transmission. • Curves & measurements with equations, two guided experiments with a verification bench, and a Learn & assess tab with lessons and a quiz.
For an ideal limp sheet at normal incidence, the power transmission fraction is τsheet = 1 / [1 + (2π f m′ / (2ρc))²], which gives about 6 dB more loss for each doubling of mass or frequency. With an open area fraction ε the wall behaves as two parallel energy paths: τtotal = ε + (1 − ε) τsheet. Transmission loss is TL = −10 log10 τ, and the receiving level is the incident level minus TL.
Because an opening transmits essentially all the sound that reaches it, a leak of only 1% limits total loss to about 20 dB no matter how heavy the sheet is.
The wall is an ideal lossless limp sheet at normal incidence with ρ = 1.2 kg/m³ and c = 343 m/s. There is no STC or Rw rating, no flanking paths, no stiffness or coincidence dip and no room gain, so the results show trends rather than rated wall performance. The message to take away is that sealing penetrations can matter more than adding mass.
An open area transmits almost all incident sound, so it adds a parallel path with transmission near 1. Total transmission becomes ε + (1 − ε)τsheet, and once ε dominates, the wall's mass hardly matters. A 1% opening caps total loss near 20 dB.
For a limp sheet, transmission loss rises about 6 dB each time surface mass or frequency doubles. The simulator evaluates the full expression rather than the simple rule of thumb.
It is the portion of the transmitted power that passes through the opening rather than through the vibrating sheet. It approaches 100% when the sheet is heavy and the leak is open.
No. It does not model STC or Rw ratings, flanking transmission, wall stiffness, coincidence or room gain. It is an ideal limp-sheet teaching model at normal incidence.