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What’s the Difference? Subtitles for the Deaf and Hard of Hearing (SDH) v. Closed Captions

  • TV with remote

    “Tomato, tomahto.” That’s what people might think when seeing the words “subtitles” and “captions,” but, there actually is a difference. Before fully understanding the difference between subtitles for the Deaf and hard of hearing (SDH) and closed captions, it might be helpful to first understand the difference between subtitles and captions!

    Subtitles vs. Closed Captions

    How are they alike?

    Both subtitles and closed captions are synchronized with the media so the text can be viewed at the same time the words are spoken. Typically, both closed captions and subtitles can be turned on or off by the user.

    How are they different?

    Subtitles are intended for hearing viewers who do not understand the language. For this reason, subtitles only show the spoken content but not the sound effects or other audio elements. They are usually used to refer to translations, for instance subtitles for a foreign film.

    However, closed captions on the other hand, are meant for Deaf and hard of hearing audience members. They communicate all audio information, including sound effects, speaker IDs, and non-speech elements. Closed captions are written in the source language of the video. They originated in the 1980s and are required by law for most video programming in the United States.

    What Are Subtitles for the Deaf and Hard of Hearing?

    So now that you know the similarities and differences of subtitles and closed captions, let’s add one more into the mix. SDH are subtitles in the source language of the video that also include important non-dialogue audio sound effects and speaker identification. While normal subtitles assume the viewer can hear the audio but doesn’t know the spoken language, SDH assume that the viewer cannot hear the audio (like with captions). They are intended to emulate closed captions on media that does not support closed captions, such as digital connections like HDMI.

    The Difference Between SDH and Closed Captions

    Subtitles SDH Closed Captions
    Synched with video Yes Yes Yes
    Can be turned on/off Yes Yes Yes
    In source language Yes Yes
    Speaker Identification Yes Yes
    Sound effects Yes Yes
    Text appearance Varies Varies Usually white text on black background
    Onscreen placement Centered lower bottom third Centered lower bottom third Varies
    Encoding Supported through HDMI Supported through HDMI Not supported through HDMI


    SDH differ from closed captions in a number of ways. The first difference is in appearance. Closed captions are typically displayed as white text on a black band, whereas SDH are usually displayed with the same proportional font of translation subtitles. More and more often, however, both subtitles and closed captions have user control options that allow the viewer to change the color, font, and size of the text.


    SDH and closed captions also differ in terms of placement. Closed captions can usually be aligned to different parts of the screen, which is helpful for speaker identification, overlapping conversation, and avoiding interference with important on-screen activity. SDH text is usually centered and locked in the lower bottom third of the screen.


    The biggest difference between SDH and closed captions is that they are encoded differently. While closed captions are encoded as a stream of commands, control codes, and text, subtitles are often encoded as bitmap images – a series of tiny dots or pixels.

    The difference between SDH and closed captions was made particularly apparent by the move from analog TVs to high-definition media. Blue-ray, as well as other HD disc media, do not support closed captioning, but will support SDH subtitles.

    So while shifting from analog to digital TV gave us crystal clear picture and uninterrupted sound, it also brought about major difficulties for Closed Captioning (CC).

    Enabling CC on an analog TV was simple – the TV did all the CC decoding. With the introduction of digital HDTV services (cable, satellite, etc.) the responsibility of decoding CC was put into the Set Top Boxes. To make matters more confusing, all of these Set Top Boxes have different ways of enabling CC. Even though all set-top boxes are required to support CC, the implementation can vary significantly between products, causing a great deal of confusion.

    SDH provides accessibility for HD disc media. Just as closed captions are beneficial to people who aren’t Deaf or hard of hearing, SDH make content more accessible to a wide range of people:

    • They improve comprehension for ESL speakers
    • They help viewers with attention deficits or cognitive differences focus on the video
    • They help viewers understand people with thick accents or speech impediments
    • They improve the viewing experience in sound-sensitive environments

    It should be noted, however, that SDH do not satisfy the FCC’s requirements for closed captioning of broadcast video. For this reason, in addition to the ever-changing technology, it seems reasonable to believe that SDH may become obsolete in the not-so-distant future.


    This post was originally published on May 21, 2014 by Lily Bond as “How Subtitles for the Deaf and Hard-of-Hearing (SDH) Differ From Closed Captions,” and has been updated.

    Need closed captions, subtitles, or both? Get started with 3Play Media today!

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2 Responses to What’s the Difference? Subtitles for the Deaf and Hard of Hearing (SDH) v. Closed Captions

  1. Leonora says:

    Thank you so much. You’ve made it so clear, finally someone has. I’m hard of hearing and without subtitles it’s just about impossible to understand if the actors don’t speak properly or have an accent. I purchase many DVDs and subscribe to Netflix, but only order with subtitles. So many of the older films and classic British films lack subtitles so I’m limited. Thanks again for your clear and understandable information.

    • Elisa Edelberg says:

      Hi Leonora, thank you for your comment. I’m so glad that you found this post informative! We hope to continue educating individuals about the importance of a more accessible world.

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