The term 'Stereo Alternative' refers to two different audio formats: QUAD and Mono. QUAD is a four-channel audio format that was popular in the 1970s, while Mono is a single-channel audio format that has been around since the early days of recorded sound. Both formats are still used today, although QUAD is less common. QUAD provides a more immersive listening experience than Mono, as it allows for more spatial separation between the left and right channels. Mono, on the other hand, is simpler and more efficient, making it a popular choice for radio broadcasts and podcasts.