Captions vs Subtitles vs SDH: What's the Difference?

Open the language menu on any streaming app and you will often see three options that look interchangeable: subtitles, closed captions, and SDH. They are not the same, and picking the wrong one can mean missing sound effects, getting a translation you did not want, or losing speaker labels. Here is what each one actually does and how to customize how they appear.

Key takeaways

• Subtitles assume you can hear the audio and show only the dialogue, often translated into another language.
• Closed captions (CC) assume you cannot hear and add speaker labels, sound effects, and music cues; they can be toggled on and off.
• SDH is captions delivered as a subtitle track, used on streaming services that do not support legacy CC.
• SDH and CC carry the same information; they are just encoded differently.
• Most platforms let you customize caption size, color, and font, though options vary by device and service.

Subtitles: dialogue only

Subtitles were designed for viewers who can hear the audio but do not understand the language. They show the spoken dialogue, frequently as a translation, and they assume you can already hear everything else: the music, the door slam, the off-screen voice. They will not tell you that ominous music is playing or that a phone is ringing, because they assume you can hear it.

So if you turn on plain subtitles in your own language, you get just the words being spoken, nothing more.

Closed captions: built for the deaf and hard of hearing

Closed captions assume you cannot hear the audio at all, so they include far more than dialogue:

• Speaker labels telling you who is talking, useful when characters are off-screen.
• Sound effects like a door creaking or a gun firing.
• Music cues noting when a song plays or the mood the score sets.

Closed captions can be toggled on and off, which is what the "closed" means. They originated in broadcast TV, where they are encoded as a stream of control codes and text. One technical quirk: traditional closed captions are not supported over HDMI, which matters for how content travels through modern devices.

SDH: captions in subtitle clothing

This is where most streaming confusion comes from. SDH stands for Subtitles for the Deaf and Hard of Hearing, and it carries the same content as closed captions, dialogue plus speaker labels, sound effects, and music cues, but it is delivered as a subtitle track rather than a legacy CC track.

Streaming platforms like Netflix, Disney+, and Hulu use SDH because their digital delivery does not support old broadcast CC. Functionally, SDH and CC give you the same experience. SDH even has a slightly higher character limit per line (around 42 versus 32 for CC) and, because it is rendered like subtitles, it is more flexible to style.

Here is the quick decision table for picking the right track:

You want	Choose	Includes dialogue	Includes sound effects and labels	Often translated
Just the spoken words	Subtitles	Yes	No	Yes
Full experience on broadcast/disc	Closed captions (CC)	Yes	Yes	No
Full experience on streaming	SDH	Yes	Yes	Sometimes
A foreign film in your language	Subtitles (translated)	Yes	No	Yes

Customizing how captions look

The appearance of captions, especially SDH, is often adjustable. Many TVs, players, and streaming services let you change:

• Text size for readability.
• Font style.
• Color of text and sometimes the background.
• Background opacity, so you can add a dark box behind the words for contrast.

1. Look in your TV's accessibility settings, your streaming device's settings, or the app's playback menu.
2. Adjust size first; larger text is the most common fix for hard-to-read captions.
3. Add a background box or shadow if captions disappear against bright scenes.
4. Note that settings live in different places: some are system-wide on the device, others are per-app.

Because these options depend on the specific TV, player, and service, the same show can look different depending on where you watch it. If your captions are too small or wash out, check both the device-level and app-level settings.

A few practical tips

• If a service only offers plain subtitles and you want sound cues, look for a separate SDH or CC entry in the same menu.
• Apple TV+ is notable for letting you choose between CC and SDH on some programming, so you can pick your preferred style.
• If captions are out of sync rather than missing, that is an audio-video timing issue, not a caption setting; our lip sync delay fix covers timing problems.

For broader streaming setup, our streaming device buying guide covers which platforms offer the most consistent accessibility options across apps.

Frequently asked questions

What is the difference between subtitles and closed captions?

Subtitles assume you can hear and show only the dialogue, often translated. Closed captions assume you cannot hear and add speaker labels, sound effects, and music cues. Captions carry far more information than plain subtitles.

What does SDH mean?

SDH stands for Subtitles for the Deaf and Hard of Hearing. It contains the same information as closed captions, including sound effects and speaker labels, but is delivered as a subtitle track. Streaming services use it because they do not support legacy broadcast CC.

Are SDH and closed captions the same?

Functionally, yes. Both include dialogue, speaker labels, sound effects, and music cues. The difference is technical: closed captions are an encoded CC track, while SDH is rendered as a subtitle track, which makes SDH more flexible to style.

Can I change the size and color of captions?

Usually, yes. Most TVs, streaming devices, and apps let you adjust caption size, font, color, and background. The setting may be at the device level or per app, so check both if you cannot find it.