Every sound we hear is directionally encoded by reflections in our outer ears and reflections off shoulders. Brain decode this information and presents a sonic image of the world around us. Spaced microphonespicked up the sound that was carried by cable to receiving point, a distance of 3 km. Not really stereophonic, because earphones were used instead of loudspeakers.
Aural crosstalk is a significant component in stereo reproduction.
The stereo effect relies on certain cues that our ear-brain system can interpret. Spacing of the microphones Small, but important differencies exist between the signals in the two channels. These differencies are key to the stereo effect. Sound arrives at both microphones at the same instant and with equal intensity. Centered phantom image between the loudspeakers.