Glossary
Subtitles for the deaf and hard of hearing (SDH)
SDH stands for subtitles for the deaf and hard of hearing. They show the dialogue plus the sound effects, music and speaker identification that a hearing viewer would get from the soundtrack.
Updated October 17, 20262 cited facts, each traced to its source
Also called SDH.
SDH subtitles are a text version of a program's dialogue plus the non-speech sounds that a hearing viewer would hear. The letters stand for subtitles for the deaf and hard of hearing. They are written for viewers who cannot rely on the soundtrack, so they include the sound effects, music and speaker names that a plain subtitle leaves out.
SDH adds the sounds that plain subtitles leave out
Plain subtitles translate or transcribe the dialogue. The UK broadcast code defines subtitling for people with hearing loss as text on screen representing speech and sound effects 1. SDH follows that idea: the sound effects are part of the text, not an afterthought.
US closed captions follow the same principle. The FCC rule says captioning must provide non-speech information such as the identity of speakers, music, sound effects and audience reaction 2. The detailed style rules differ by country and by platform, so check the requirements of the place where the subtitles will be shown.
Example: the same line, two ways
A plain subtitle for a scene in a car shows only the dialogue: "Get out of the car." An SDH subtitle adds what a hearing viewer would hear and see: the sound of tires squealing, and the speaker's name when the speaker is off-screen. The second version lets a deaf viewer follow the scene without the soundtrack.
Why it matters for transcription
An SDH file is a full transcript of the soundtrack written as timed text. Transcribers decide which sounds matter, how to label each speaker and how to mark music, and those choices affect how readable the result is. Speaker names are the hardest part when several people talk, which is why the speaker diarization entry covers how software tells speakers apart. For the style choices behind a clean transcript, read our guide to verbatim vs clean verbatim transcription. For how caption and subtitle formats differ, see captions and subtitles.
SDH is delivered in the same kinds of files as other captions, such as WebVTT. If the text is drawn into the picture instead, it becomes open captions.
Related terms
- Closed captions: captions the viewer can switch on or off, which often carry the same sound notes.
- Open captions: text drawn into the picture for every viewer.
- Verbatim transcription: a transcript that keeps every word and sound, which is the closest style to SDH.
Evidence
Every number on this page, with where it comes from. Open a fact to see the exact words in its source.
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Related terms
- Transcription: How to Turn Audio and Video Into TextThe topic this term belongs to
- Clean verbatimClean verbatim is a transcript that removes filler words, stutters, repetitions and false starts while keeping the speaker's wording and meaning. It is the usual choice for reading, captions and coding, where hesitations add noise rather than information.
- Closed captions (CC)Closed captions (CC) are a text version of a program's dialogue and relevant sounds that the viewer can turn on or off. The word closed means the viewer chooses whether to see them, which separates them from open captions.
- Forced alignmentForced alignment is the process of matching a known transcript to its audio so that each word or phone gets a start and end time. Unlike open speech recognition, it does not decide what was said; it only finds when each word was said.
- Open captionsOpen captions are text drawn onto the frames of a video, so every viewer sees them and nobody can switch them off. They are also called burned-in captions or hardcoded subtitles.
- SubRip subtitle file (SRT)A SubRip subtitle file, or SRT, is a plain-text file of numbered caption blocks. Each block has a start and end time in hours, minutes, seconds and milliseconds, followed by the caption text. It is one of the most common caption formats on the internet.
- Timestamp (transcription)A timestamp in a transcript is a time marker, such as 00:12:15, that shows when the nearby text was spoken in the recording. Timestamps let readers jump to a passage, and they can be attached to whole segments or to single words, with different accuracy.
- Transcription foot pedalA transcription foot pedal is a switch that controls audio playback with the foot, so a transcriber can start, pause and rewind a recording while typing. It is also called a foot control or foot pedal.
- TranscriptionistA transcriptionist is a person who listens to recorded speech and types it as text, such as a clinician's dictated report. Speech recognition now writes first drafts, so much of the work has shifted to checking and correcting machine text.
- Turnaround time (TAT)Turnaround time (TAT) is how long a transcriber or service takes to deliver a finished transcript after an order is received. Court schedules define it in calendar days or hours, counted from the order.
- Verbatim transcriptionVerbatim transcription writes down exactly what is said, including filler words, false starts, repetitions and non-speech sounds, with no tidying. Researchers and legal teams use it when the way someone speaks is part of the record.
- WebVTT (VTT)WebVTT (Web Video Text Tracks, usually shortened to VTT) is a plain-text file format for timed captions and subtitles on the web. A .vtt file is a list of cues, and each cue gives a start time, an end time and the text to show.