Noise Reduction Calculator — dB Reduction from Materials
Reduced Noise Level
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Noise Reduction
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Perceived Change
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Understanding Noise Reduction
Sound reduction is measured in decibels (dB). The STC (Sound Transmission Class) rating indicates how much sound a barrier blocks. Every 10 dB reduction sounds roughly half as loud to the human ear, even though it represents a 90% reduction in sound energy.
Common STC ratings: hollow-core door (20), single drywall (33), double drywall (40), insulated wall with resilient channels (45-50), concrete block (50). STC 40 means normal speech is inaudible through the wall. STC 50 means loud speech is barely audible.
Distance also reduces sound: doubling the distance reduces level by about 6 dB outdoors. Indoors, reflections limit distance attenuation. For best results, combine mass (heavy materials), air gaps (decoupled walls), and absorption (insulation).
Frequently Asked Questions
What does a 10 dB reduction sound like?
A 10 dB reduction sounds approximately half as loud. A 20 dB reduction sounds about 1/4 as loud. A 30 dB reduction sounds about 1/8 as loud. Human perception of loudness is logarithmic.
What STC rating do I need for a home studio?
A home music studio should aim for STC 50-60 between the studio and adjacent rooms. This typically requires double drywall on resilient channels with insulation, plus a solid-core door with seals.
How do I soundproof an existing wall?
Add a second layer of drywall with Green Glue compound between layers (+8-10 STC). For more reduction, build a decoupled wall on resilient channels with insulation (+15-20 STC). Seal all gaps and penetrations.