SDH Subtitles Explained: Subtitles for the Deaf and Hard of Hearing

SDH subtitles combine translated dialogue with audio descriptions and speaker IDs to make video content fully accessible to deaf and hard-of-hearing viewers in any language.

SDH stands for Subtitles for the Deaf and Hard of Hearing. SDH subtitles are a specific type of subtitle that combines two things: translated dialogue (like standard subtitles) and audio accessibility information (like closed captions). This combination serves viewers who are deaf or hard of hearing and who are watching content in a language other than their own — or who need both the translation and the audio accessibility layer simultaneously. The audio accessibility elements in SDH subtitles include descriptions of significant non-speech sounds in square brackets — [tense music], [explosion], [crowd cheering], [doorbell rings] — and speaker identification when it's not visually obvious who is speaking. SDH subtitles are widely used in DVD and Blu-ray releases, streaming platforms, and digital download services, where they serve as the single subtitle track that meets both language translation and hearing accessibility requirements. They are technically optional in the same way as other soft subtitles — viewers can toggle them on and off — which distinguishes them from open captions burned into the video.

Creating high-quality SDH subtitles requires additional production steps compared to standard subtitles. Beyond translating the dialogue, you need to review the audio of the entire video for significant non-speech sounds and describe them concisely in the subtitle file. The descriptions should be specific enough to be informative without being so detailed that they slow reading pace or crowd the screen. [Suspenseful orchestral music begins] is more useful than [music]. [Phone rings twice] is more useful than [sound]. For speaker identification, include the speaker's name or a clear identifier at the start of each subtitle card when the speaker is not visible on screen. If a character speaks off-screen or if two similar voices might be confused, speaker labels prevent the disorientation that deaf viewers otherwise experience. Formatting conventions for SDH include using italics for off-screen speech or speakers who cannot be identified — [narrator] or [off-screen voice] conventions vary by production house but consistency is key. For music, the current best practice is to describe both the music and whether it has lyrics, and to subtitle significant lyrics where they are relevant to the plot or emotional content.

SDH subtitles are relevant to accessibility law in several jurisdictions. In the UK, Ofcom's broadcast regulations require that a specified percentage of programming is subtitled, and the subtitle quality standards they enforce are broadly equivalent to SDH quality — they should cover all relevant audio content, not just dialogue. In the United States, the FCC requires closed captions for broadcast and cable programming, and streaming services that distribute broadcast content are also subject to these requirements. The Twenty-First Century Communications and Video Accessibility Act (CVAA) extended captioning requirements to online video. The European Accessibility Act, which came into full effect in 2025, requires that digital services — including video-on-demand platforms — meet accessibility standards including audio description and captioning for deaf users. For content producers and distributors, this means SDH subtitles are increasingly not a nice-to-have but a legal requirement for certain types of content. Even producers not subject to legal requirements benefit from SDH — deaf and hard-of-hearing audiences represent a significant proportion of the population in every country, and providing genuinely accessible content builds audience loyalty and positive brand association. Zingo can help you generate the timing framework for your SDH subtitle file, which your accessibility specialist can then annotate with sound descriptions and speaker labels.