TC is a single number rating that indicates the sound transmission loss over a defined range of frequencies of a door assembly between adjacent closed rooms. Higher values equate to better sound reduction performance. Decibels dB, are used to express the intensity of a sound wave. Examples of decibels levels are:
100-120 Deafening industrial machinery, jet engines 80-100 Very loud cocktail party, boom box 60-80 Quiet speech 20-40 Faint soft whisper, recording studio 0-20 Very faint acoustical laboratories, deep caves