From the Greek meaning “solid sound,” referring to the construction of believable, solid, stable sound images. This has come to mean any sound system with two loudspeakers. However, it precisely refers to a sound system which provides the listener with an illusion of directional realism, regardless of how many channels are used. For example, the use of a reverberation effect with strong early reflections and a fairly fast decay are an effective way of creating a wide stereo spread from a mono source, such as a voice or instrument which has been recorded with a single microphone.”