Definition
Share of voice in AI is the percentage of AI-generated answers about your category that mention or cite your brand versus competitors. It adapts the classic media metric to answer engines: sample the questions your buyers ask, run them across engines, and count whose products appear. Because AI answers concentrate on a few sources, share of voice tends to be winner-take-most — which is why early GEO investment in a niche can lock in outsized visibility. To make the metric operational, fix three variables before you measure: the prompt set (real buyer questions, not vanity keywords), the engine list, and the sampling cadence — AI answers vary run to run, so single-shot checks mislead. Reported movement should always come with its prompt set attached; a share-of-voice number without the underlying questions is marketing, not measurement.