stereophony

Streophony, or stereo sound, is a method of sound reproduction that uses two or more independent audio channels to create the impression of a three-dimensional sound field. The typical arrangement uses two channels—left and right—that, when played through two loudspeakers or headphones, can convey directional cues and a sense of space beyond what a single channel can provide.

In stereo, the listener localizes sounds through differences between the channels, such as interaural time differences (the slight arrival time difference of a sound at each ear) and interaural level differences (loudness differences). Reflections from the listening room and the ear’s own filtering contribute to the perception of distance, width, and envelopment, producing a more natural and immersive experience than mono playback.

Recording and production techniques for stereo involve specific microphone configurations and mixing practices. Common stereo mic methods include coincident approaches (such as XY) and near-coincident or spaced pair techniques (such as ORTF, spaced omnis), as well as Mid-Side (MS) decoding. Mixing decisions like panning, level balance, and reverberation shape the final stereo image. Playback can be through two loudspeakers set apart at an angle or through headphones, which can preserve or highlight different spatial cues.

History and usage: stereophony became commercially popular in the mid-20th century and remains the standard for music recording, film sound, broadcasting, and many multimedia applications. It has evolved into multichannel formats (surround sound), but the basic principle of using two or more channels to convey space remains central.