Reverberation time plays a major role in the quality of sound heard in a concert hall. Acoustical engineers carefully design concert halls to achieve a typical reverberation time between one and two seconds. Rooms designed for speech should have reverberation times less than one second, movie theaters a little over one second, and rooms designed for organ music have as much as two seconds. If the reverberation time for middle and high notes is too short, the sound will diminish almost instantaneously and the room will sound “dry.” A “full” bass tone requires a longer reverberation time for low notes. If the reverberation time is too long, however, as it is in many gymnasiums, the echoing effects will interfere with the new sounds, making music sound “mushy” and words of a speaker difficult to understand.