Why Speaker Diarization Still Fails in Real-World Conversations

Speaker diarization systems perform well in clean, two-person calls but struggle significantly in realistic settings involving multiple speakers, interruptions, and background noise. A core architectural flaw in most systems assumes only one person speaks at any given moment, making overlapping speech a critical blind spot where one speaker's words are simply lost. Short verbal reactions like 'yeah' or 'right' are routinely misattributed to whoever was already speaking, quietly corrupting transcripts without triggering obvious errors. These failures are compounded by the fact that standard evaluation metrics often fail to detect some of the worst diarization errors. Addressing these issues requires systems that treat overlap and back-channels as first-class events rather than noise to be filtered out.