Calculate the absorption coefficient and NRC of acoustic materials.
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About this calculator
Quick Reference
IiIncident sound energy
IrReflected sound energy
ItTransmitted sound energy
α = 1Total absorption (no reflection)
Overview
The sound absorption coefficient (α) is the fraction of sound energy absorbed by a material. It ranges from 0 (perfect reflection) to 1 (perfect absorption).
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Pro Tips
NRC (Noise Reduction Coefficient) is the average of absorption coefficients at 250, 500, 1000, and 2000 Hz.
Materials like acoustic foam have high α at mid-to-high frequencies.
Hard surfaces like concrete or glass have very low α (close to 0).
Total Energy = Absorbed + Reflected + Transmitted.
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Fun Facts
"Open windows have an absorption coefficient of 1.0 because no sound is reflected back into the room."
"Large auditoriums use specific materials to tune the reverberation time using targeted absorption."
"Anechoic chambers use massive wedges of foam to achieve absorption coefficients very close to 1 across all frequencies."
