Glass Glossary

Sound Transmission Class (STC)


Last Updated: November 23, 2023

Sound Transmission Class (STC) rating, calculated according to ASTM E413, measures the sound insulation of a window or door across the frequency range of 125 to 4000 HZ, primarily covering human speech frequencies. A higher STC rating indicates superior sound insulation.

For homeowners, STC ratings are critical when selecting windows and doors, especially in noisy environments. Considerations include:

  • Desired Quietness: Higher STC-rated windows or doors offer increased sound insulation for a quieter living environment.
  • Location and Noise Levels: Homes near high-noise areas benefit from higher STC ratings, while those in quieter neighborhoods may not need the same level of sound dampening.

Comparing STC and OITC

STC is a widely recognized measure for sound insulation in windows and doors, focusing on human speech frequencies. OITC, on the other hand, covers a broader frequency range (80 to 4000 Hz), including lower frequencies often associated with external noise.

Both STC and OITC ratings inform your window or door selection based on sound insulation needs. Assess your specific requirements and environment to determine which metric is more applicable for your situation.