"Typically, the plate is a large (one by two meters, or 39.37 by 78.74 inches) sheet of steel suspended in a tubular steel frame. In theory, the plate simulates a large concert hall, or church, with a decay time (RT-60; the time required for the level of the reverb to diminish by 60 dB) of approximately five seconds at approximately 500 Hz. A driver attached to the plate excites it, and as the sound waves travel through it, the plate flexes. The plate's motion is then picked up by one or two contact mics, and added to the dry signal at the mixer. Transients do not twang or boing, but behave much as they would in a reverberant room, sounding smooth and natural. As an additional feature, incorporating a damping plate to change the decay time of the reverberated signal can be included in the design."