STC

Definition

STC is a single-number rating of how a wall, door or window reduces speech-range airborne sound. A single layer of drywall on timber might sit in the low 30s; staggered studs, extra mass and a damped air gap climb toward the 50s. Low bass (subwoofer, HVAC) leaks around STC because the curve ignores the lowest octaves. This site’s estimator is mass-law plus a crude air-gap bonus, not a lab certificate. Flanking paths through ducts beat any spreadsheet.

Calculators that use this

• Signal, cables & storage

  Soundproofing STC Estimator

  A mass-law-ish STC estimate from surface mass and an air gap. Higher STC, quieter neighbours — bass still leaks.

• Speaker placement & acoustics

  Acoustic Panel Coverage Estimator

  Estimate how many panels you need from room size, target wall coverage and panel area. Cinema rooms often want 20–40%.

• Speaker placement & acoustics

  Room Modes / Standing Wave Calculator

  Map the first axial modes from length, width and height. Speed of sound 343 m/s. Then plan subs and treatment.