Reverberation time is the period of time within the sound pressure level is reduced by 60 dB. In other words, this means the sound pressure level diminishes into one millionth of the original. Paying attention to the reverberation time in spesific rooms gives us a chance to make speech more understandable. Therefore it is of major importance when planning and designing concert halls, theaters, conference and presentation rooms.

Reverberation time is always measured when evaluating the sound reduction index and impact sound pressure level. Only this way it is possible to normalize the results to make empty and furnished rooms equal for comparison.