Navigation: Acoustics101
Acoustics 101
Propagation of sound
Wavelength & Loudness
Speed of Sound
Equal Loudness Contours
Perception of sound
Inverse Square Law
Reverberation
Adding decibels
Sound Absorption
What is Noise
Noise reduction
Relative Loudness
Noise interference w/ speech
Speech Intelligibility
Signal to Noise Ratio (S/NR)
Speech Directivity
Speech privacy
Masking sound systems
Transmission of sound
Resonant Frequencies
Sound Transmission Class
Sound Isolation
Sound sealants
Sound absorption coefficients
Noise sources
Metric conversions
Sound Transmission Class (STC)The Sound Transmission Class is a single number rating of the effectiveness of a material or construction assembly to retard the transmission of airborne sound. The sound transmission loss between the source and receiving rooms are plotted on a graph by frequency and sound level in decibels. The STC curve is a sliding contour that is fitted to the performance data plotted in a manner that will allow no more than 32 deficiencies below the appropriate contour. The maximum deficiency at any given frequency shall not exceed 8 decibels. 
Once the appropriate contour has been selected the STC is determined by the decibel value of the vertical scale at 500 Hz. The STC is expressed as a single STC number (Example STC 32) Note that the STC contour is similar to the inverse of the equal loudness contour, insofar as it discounts the lower frequency sounds to reflect how our ears perceive the lower frequency sounds.
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