What are SDH subtitles?
SDH (Subtitles for the Deaf and Hard-of-hearing) are same-language subtitles that include non-speech audio cues — music, sound effects, speaker IDs — following accessibility conventions. They're the streaming-era equivalent of closed captions.
Detail
SDH stands for Subtitles for the Deaf and Hard-of-hearing. Unlike standard subtitles that only transcribe spoken dialogue, SDH subtitles also describe significant non-speech audio: [upbeat music], [door slams], [NARRATOR:], [crowd cheering]. This matches the content of closed captions (CC) — the difference is delivery: CC is a broadcast-standard closed track (CEA-608/708), while SDH is delivered as a subtitle stream inside a digital file (SRT, VTT, or a streaming container). Netflix, Disney+, and HBO use SDH as the same-language subtitle label. For accessibility compliance (ADA, Section 508, WCAG 1.2.2), SDH-formatted content satisfies the requirement for deaf and hard-of-hearing viewers. If you're captioning for a platform that requires accessibility compliance, author your SRT to SDH standards: include speaker labels, music cues, and significant sound effects, not just the spoken words.
- Include speaker IDs when multiple speakers are off-screen: [JOHN:] or (John)
- Include music cues: [upbeat music] or [instrumental]
- Include significant sound effects: [phone ringing], [door slams]
- Use square brackets for non-speech audio; parentheses for tonal descriptions
- Do not include every background noise — only sounds that carry meaning