Optical Analogy of a Loudspeaker in a Reverberant Room

Abstract

When a speaker talks in a large, reverberant room, the numerous reflections from the various surfaces fill the room with sound that may be regarded as an acoustic “fog.” The speaker thus has difficulty in making himself “seen” (heard) through this “fog” by distant auditors. By analogy with an auto in a real fog, he turns on his “acoustic headlights” (loudspeakers) to make his speech “visible” (understood) by auditors. Care must be taken to avoid “acoustic glare” (excessive loudness), which is also likely to produce a “reflection” (echo) from distant walls. This optical analogy has been found helpful in explaining the acoustic effects set up by reverberation in rooms.