STEREOPHONIE

The term of “stereophony” is based on the Greek words of stereos = spatial, solid phone = sound. In practice, it is used for a 2-channel sound playback with the speakers set up to form the two ends of a straight line and thus representing the first spatial dimension or x-axis...

Besides, the playback is to occur within the equilateral stereo triangle, the so-called “sweet spot” (our symbolic attribution: bronze).

Remark:
there is no direct connection between the original meaning of the term and its modern use as “audio playback based on two loud-speakers”.