Speech data annotation: speakers, overlaps and the sounds that are not words
· a.pannella87
Last updated: 27 October 2026 · OpenJob editorial team
Speech data annotation adds three layers on top of the words: diarization (who is speaking, as Speaker 1, Speaker 2), overlap handling when voices talk at once, and audio-event tags for laughter, coughs, music or other sounds. Each project defines its own rules, and following the guide matters more than your own instinct.
Key points
- Speaker labels identify voices, never names or personal traits.
- Overlap rules differ: parallel segments, dominant speaker or an overlap tag.
- Use the fixed tag list for non-speech sounds; do not describe them freely.
- The most common habit to fix is marking speaker changes late.
Speech annotation projects teach models to handle real audio, which is messier than any script. The work usually includes three layers on top of the words themselves.
Who is speaking: diarization
Diarization means splitting a recording by speaker. You mark each change and give each voice a label such as Speaker 1 and Speaker 2. The labels identify voices, not people: you do not guess names, ages or anything else the guidelines do not ask for.
The hard cases are short interjections (“yes”, “mm-hm”) and two people who sound alike. Replaying at reduced speed and watching the waveform helps more than listening harder.
When voices overlap
Projects handle overlap differently. Some want both speakers transcribed in parallel segments, some want the dominant speaker only, some want an overlap tag. There is no universal rule, so follow the project guide even if a different approach seems more natural.
Sounds that are not speech
Audio-event labelling covers laughter, coughs, music, a door closing, background television. Guides usually give a fixed list of tags. Two common mistakes: tagging every faint noise when only relevant ones are wanted, and describing a sound in your own words instead of using the tag list.
A practice routine
Take a public-domain recording with two or more speakers, such as an old radio interview, and mark speaker changes for two minutes. Then compare your boundaries with the moments you can see in the waveform. You will quickly learn whether you mark late, which is the most common habit to fix.
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Frequently asked questions
What is diarization?
Diarization means splitting a recording by speaker and labelling each voice, for example Speaker 1 and Speaker 2. Labels identify voices only: annotators do not guess names, ages or other details the guidelines do not ask for. Short interjections and similar voices are the hard cases.
Do I need special software for speech annotation?
Projects usually provide their own tool in the browser. What helps is good closed headphones, a quiet room and the habit of replaying boundaries at reduced speed while watching the waveform. Check the project’s equipment requirements before the qualification test.
How do I practise speech annotation for free?
Take a public-domain recording with two or more speakers, such as an old radio interview, and mark speaker changes for two minutes. Compare your boundaries with the waveform. Then tag non-speech sounds using a short fixed list, as projects require.