Noise Reduction Calculator
Calculate how much a noise barrier reduces sound levels.
Enter source decibels, barrier NRC rating, and distance for the reduced dB level.
Reduced Noise Level
Noise reduction depends on barrier properties and distance from the source.
Distance attenuation (inverse square law):
dB loss from distance = 20 × log₁₀(d₂ / d₁)
Sound drops ~6 dB each time distance doubles.
Barrier reduction:
A barrier with a given NRC (Noise Reduction Coefficient) typically provides:
Barrier reduction ≈ NRC × 30 dB (simplified estimate)
Combined formula:
Reduced dB = Source dB − Distance attenuation − Barrier reduction
Common NRC ratings:
- Open air (no barrier): 0.00
- Single-pane window: 0.15–0.25
- Drywall partition: 0.30–0.50
- Acoustic panel: 0.70–0.90
- Soundproof wall: 0.90–1.00
Decibel reference levels:
- 30 dB: Quiet whisper
- 50 dB: Normal conversation
- 70 dB: Vacuum cleaner
- 85 dB: Heavy traffic — hearing damage threshold
- 100 dB: Power tools
- 120 dB: Pain threshold