Decoder. plain-English AI glossary

Speaker Diarization

▲ Rising

Identifying and separating who spoke when in an audio recording - marking "Speaker A: [0:00-1:23], Speaker B: [1:24-3:00]."

Think of it like

Reading a script with multiple characters and labeling which character speaks each line.

Example

A meeting recording: the system marks "Alice: 0:00-1:30, Bob: 1:31-2:15, Alice: 2:16-3:00."

How it actually works

Combines voice activity detection (is anyone speaking?), voice embedding extraction (speaker signature per segment), and clustering (group similar speakers). Assumes a speaker has consistent acoustic characteristics. Challenges: similar voices, overlapping speech, channel differences, long recordings (speaker drift). Typically: extract speaker embeddings (x-vector, d-vector), run clustering (spectral, agglomerative). Recent: end-to-end differentiable models (PyAnnote, ECAPA-TDNN).

For product teams

Essential for meeting transcripts, podcast chapters, media indexing, and accessibility.

For engineers

Datasets: AMI, ICSI. Metrics: diarization error rate (DER), composed of miss, false alarm, and speaker confusion. Models: x-vector, ECAPA-TDNN.

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