Estimate sound transmission loss through a wall, barrier, window, door, panel, or partition. Enter the incident sound level and transmitted sound level, or enter a transmission coefficient, to calculate TL, transmitted level, and sound reduction details.
Level difference:
If you enter incident and transmitted sound levels, the calculator subtracts transmitted dB from incident dB to estimate transmission loss.
Transmission coefficient:
If you enter a coefficient, the calculator uses 10 × log10 of the inverse coefficient to estimate TL.
Transmitted level:
If you enter incident level and TL, the calculator estimates the sound level after the barrier.
A sound transmission loss calculator helps estimate how much sound is reduced by a wall, door, window, barrier, or partition. It can be useful for home theaters, studios, offices, classrooms, apartments, machinery rooms, and noise control planning.
Real-world sound isolation can be lower than calculated because of air gaps, flanking paths, weak doors, windows, vents, outlets, framing, and installation quality.
Common formulas used by this calculator:
In these formulas, τ is the transmission coefficient, or the fraction of sound energy transmitted through the barrier.
Sound transmission loss is the amount of sound reduction through a barrier, usually measured in decibels. Higher values mean better sound blocking.
No. Transmission loss is a frequency-specific or calculated reduction value. STC is a single-number rating based on transmission loss across several speech-related frequency bands.
A 30 dB transmission loss means the transmitted sound energy is about one-thousandth of the incident sound energy, based on the logarithmic relationship.
Sound can leak through gaps, doors, windows, vents, electrical outlets, ceiling paths, floor paths, framing, and other flanking paths around the main barrier.