Simultaneous Captioning

Real-time closed caption — accessibility, multilingual and hybrid events.

What simultaneous captioning is and when to use it

Simultaneous captioning — also called real-time closed caption or CART (Communication Access Realtime Translation) — is the display of text on screen as the speaker talks, with a 1 to 3-second delay. It differs from simultaneous interpretation: instead of audio in a receiver, the participant reads the text on screen.

Primary uses: accessibility for participants with hearing impairment or low hearing; multilingual events, with English captions for an international audience while the speaker talks in Portuguese; hybrid events, where remote participants get captions synced with the video; and recording and documentation, with captions embedded in the event's video file.

AI captioning vs human captioner

Technical setup and supported platforms

In-person: captions are displayed on the event screen via caption software integrated with the venue's projection system, or on individual tablets over the local network. lingo connects to the speaker's microphone audio feed via a professional audio interface.

Remote and hybrid: Zoom supports native closed captioning (CC button) with third-party integration via API; Teams Premium has integrated automatic captioning with multi-language support; Google Meet Enterprise has automatic captioning in English, Spanish and Portuguese. lingo configures the integration and monitors quality in real time.

Accessibility and the Brazilian Inclusion Law

The Brazilian Inclusion Law (Law 13.146/2015) requires communication accessibility for public events with more than 100 participants. Simultaneous captioning is one of the ways to meet this requirement — alongside Brazilian Sign Language (Libras) and audio description, depending on the event's context.

For closed corporate events without general public access, there's no specific legal requirement, but lingo recommends captioning as good ESG governance practice, especially for companies with formal diversity and inclusion policies.

Use cases for simultaneous captioning

Real-time captioning serves distinct goals. At events open to the public, it helps meet accessibility requirements. At corporate events with participants from several countries, it lets each person follow in their own language, reading on screen. In webinars and recorded meetings, captions integrated into the video broaden reach and make later consultation easier.

There is also the combined use with interpretation: the translated audio arrives through the receiver and the caption appears on the big screen, which serves audiences with different preferences. It is a common solution at congresses with mixed audiences.

How captioning is set up at in-person events

• Audio capture straight from the mixing console through a professional interface.
• Captioning software integrated with the venue's projection system.
• Positioning of screens or tablets so the whole audience can see the text.
• Adjustment of font size, contrast and number of lines.
• Monitoring throughout the event by a lingo technician.

In large rooms, a second monitor near the stage helps those at the back or in side positions.

Setup at online events

On Zoom, captions use native closed captioning, with third-party integration through API. Teams Premium has automatic captions in several languages, and Google Meet Enterprise offers captions in English, Spanish and Portuguese. When the event requires more accuracy or different languages, lingo sets up a complementary solution and monitors quality throughout the meeting.

AI or human captioner: how to choose

AI captioning has 90% to 97% accuracy in Portuguese and English with clean audio and costs 30% to 50% less. A human captioner exceeds 99% and is best for public events, live broadcasts and archived content. For internal events, webinars and training, AI is usually enough. When the event requires an official record or has critical terminology, a human is safer. The live captioning FAQ details the criteria.

Deliverables after the event

After the event, lingo delivers the caption file in .srt, .vtt or .txt, time-indexed, for use in video editing, minutes and content lookup. If the captions were generated by AI and the content will be published, a human review is recommended before release to correct names and technical terms.

Who simultaneous captioning is for

Simultaneous captioning serves audiences and contexts where audio alone is not enough. It supports deaf or hard-of-hearing people, attendees in noisy environments, audiences with a mix of languages and events streamed online, where many watch without sound. It is also useful for recording what was said, since the text can be reviewed later.

At international events, the translated caption complements the audio channel: part of the audience prefers to hear the interpreter, another part prefers to read. Offering both options broadens reach without requiring additional equipment for those already in the room.

Display best practices

• Position the caption screen where everyone can see it without looking away from the stage.
• Use a large font, high contrast and few lines at a time, for comfortable reading.
• Limit the amount of text per screen, so reading keeps up with the pace of speech.
• Offer the same caption in the event's streaming, when there is a broadcast.
• Agree with the speaker on a moderate speaking pace, which benefits both captions and audio.

In online broadcasts, captions can be inserted into the platform itself or into a visual layer of the video, depending on the available feature. lingo advises the best option after learning the platform and the event format.

Proper names, acronyms and technical terms are the biggest challenge for any captioning system. Sending the list of speakers, slides and glossary in advance reduces errors and improves legibility.

How to request simultaneous captioning

State the event format, languages, duration and venue or platform. The lingo team assesses whether the best solution is captions in Portuguese, translated captions or a combination with audio interpretation, and presents the proposal with itemized costs.

For frequent questions about technology, quality and formats, see the live captioning FAQ page. If you prefer to speak directly with the team, WhatsApp is the fastest channel to align date, languages and venue.

Captions in Portuguese, translated captions and audio interpretation

There are three main formats. Portuguese captions transcribe speech in the same language and support accessibility and following along in noisy environments. Translated captions show the text in another language, useful when part of the audience prefers to read. Audio interpretation delivers the spoken translation on receivers or in an online channel.

The formats can be combined. An international event can have audio interpretation for those who prefer to listen and translated captions on screen for those who prefer to read, from the same technical structure. lingo helps choose the combination according to audience, budget and venue infrastructure.

Quality, latency and review

Any caption generated in real time has a small delay relative to speech, and quality depends on the clarity of the audio and the speaker's pace. Speakers with strong accents, poor microphones and background noise reduce accuracy. That is why lingo works with direct audio from the mixing console and a pre-loaded glossary.

When the text will be published after the event, such as in recordings or minutes, it is worth planning a review step. Real-time transcription is an excellent starting point, but content intended for official publication should go through human checking before release.

Costs and planning

The investment depends on the number of languages, duration, chosen format and the required structure, such as screens, equipment and on-site technician. For online events, setup is usually simpler than for an in-person event with screens and audio.

Request the quote with format, languages, duration and venue or platform. The response itemizes each line and lets you compare captioning with other solutions, such as simultaneous interpretation by a human or AI interpreter. For an overview of prices, also see the page on how much simultaneous interpretation costs.

Frequently asked questions

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Lingo Qi Interpretações LTDA · CNPJ 53.834.741/0001-34 · São Paulo, SP