立体声（英语：stereo）是使用两个或多个独立的音效信道，在一对以对称方式配置的扬声器（即俗称的喇叭）上出现。以此方法所发出的声音，在不同方向仍可保持自然与悦耳。与之相对的是单声道。

美国Audio Fidelity Records公司，于1957年第一次将立体声引入商业唱片领域，这是一个十分重要的里程碑。1957年可视为唱片录音史上Mono与Stereo的重要分水岭，许多在1957年前便过世的音乐家，都因而很遗憾未能留下Stereo的录音数据。此后在1960年代，大多数唱片公司都陆续放弃单声道，全面性地转向双声道立体声录音。双声道立体声，至今仍是聆听音乐的主流规格。

Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that creates an illusion of multi-directional audible perspective. This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers (or stereo headphones) in such a way as to create the impression of sound heard from various directions, as in natural hearing. Thus the term "stereophonic" applies to so-called "quadraphonic" and "surround-sound" systems as well as the more common two-channel, two-speaker systems. It is often contrasted with monophonic, or "mono" sound, where audio is heard as coming from one position, often centered in the sound field (analogous to a visual field). In the 2000s, stereo sound is common in entertainment systems such as broadcast radio and TV, recorded music and the cinema.