Critical distance is the distance at which the reverberant sound field is equal in level to the direct sound from a sound source. For reverb times of less than 1.6 seconds, a listener could be up to 3.16 times critical distance from a sound source. For reverb times greater than 1.6 seconds, this multiplier gradually drops to a value of 1. This becomes critical in sound system design in reverberant spaces such as arenas. This calculation provides critical distance values an unaided voice with a Q (or directivity) of 2, and for a single loudspeaker with a selectable coverage pattern. Note that at very long reverb times (5 seconds) the critical distance is very short for unaided voice, and this affects speech communication.