The accuracy of automatic and human live captions in English


  • Pablo Romero-Fresco Universidade de Vigo
  • Nazaret Fresno The University of Texas Rio Grande Valley



live captioning, automatic speech recognition, accuracy, respeaking, NER model


Closed captions play a vital role in making live broadcasts accessible to many viewers. Traditionally, stenographers and respeakers have been in charge of their production, but this scenario is changing due to the steady improvements that automatic speech recognition has undergone in recent years. This technology is being used to create intralingual live captions without human assistance and broadcasters have begun to explore its use. As a result, human and automatic captions co-exist now on television and, while some research has focused on the accuracy of human live captions, comprehensive assessments of the accuracy and quality of automatic captions are still needed. This article airs this matter by presenting the main findings of the largest study conducted to date to explore the accuracy of automatic live captions. Through four case studies that included approximately 17,000 live captions analysed with the NER model from 2018 to 2022 in the United Kingdom, the United States, and Canada, this article tracks the recent developments with unedited automatic captions, compares their accuracy to that achieved by human beings, and concludes with a brief discussion of what the future of live captioning looks like for both human and automatic captions.


Working Group: EBG NER trial. (2018). Final report.

AMI (Accessible Media Inc.). (2021). Annual closed captioning reports 2020-2021 – AMI-tv (CRTC 2018-319).

Apone, T., Botkin, B., Brooks, M., & Goldberg, L. (2011). Caption accuracy metrics project research into automated error ranking of real-time captions in live television news programs. September, 1–16.

Bolaños-García-Escribano, A., Díaz-Cintas, J., & Massidda, S. (2021). Subtitlers on the cloud: The use of professional web-based Systems in subtitling practice and training. Tradumàtica: Tecnologies de La Traducció, 19, 1–21.

CAD (Canadian Association of the Deaf). (2018). Understanding User Responses to Live Closed Captioning in Canada.

Canadian Radio-Television and Telecommunications Commission (CRTC). (2015). Broadcasting notice of consultation CRTC 2015-325.

Canadian Radio-Television and Telecommunications Commission (CRTC). (2016). Broadcasting Regulatory Policy CRTC 2016-435.

Canadian Radio-Television and Telecommunications Commission (CRTC). (2019). Broadcasting Regulatory Policy CRTC 2019-308.

DGT (Directorate-General for Translation). (2019). Live Speech to Text and Machine Translation Tool for 24 Languages – Innovation Partnership – Specifications.

Dutka, ?. (2022). Live subtitling with respeaking in Polish: Technology, user expectations and quality assessment [Unpublished doctoral dissertation]. University of Warsaw.

Fresno, N. (n.d.). Live captioning accuracy in English-language newscasts in the United States. Universal Access in the Information Society.

Fresno, N. (2019). Of bad hombres and nasty women: The quality of the live closed captioning in the 2016 US final presidential debate. Perspectives: Studies in Translation Theory and Practice, 27(3), 350–366.

Fresno, N. (2021). Live captioning accuracy in Spanish-language newscasts in the United States. Lecture Notes in Computer Science (Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12769 LNCS, 255–266.

Fresno, N., Romero-Fresco, P., & Rico-Vázquez, M. (2019, June 17-19). The quality of live subtitling on Spanish television [Conference presentation]. Media for All 8 Conference, Stockholm University, Sweden.

Fresno, N., Sepielak, K., & Krawczyk, M. (2021). Football for all: The quality of the live closed captioning in the Super Bowl LII. Universal Access in the Information Society, 20(4), 729–740.

Ivarsson, J., & Carroll, M. (1998). Subtitling. TransEdit.

Jensema, C., McCann, R., & Ramsey, S. (1996). Closed-captioned television presentation speed and vocabulary. American Annals of the Deaf, 141(4), 284–292.

Jim Pattison Broadcast Group. (2020). Cover letter and report to CRTC.

Jordan, A. B., Albright, A., Branner, A., & Sullivan, J. (2003). The state of closed captioning services in the United States: An assessment of quality, availability, and use. The Annenberg Public Policy Center of the University of Pennsylvania. Report to the National Captioning Institute Foundation.

Neves, J. (2005). Audiovisual translation: Subtitling for the deaf and hard-of-hearing [Unpublished doctoral dissertation]. University of Surrey-Roehampton.

Pérez Cernuda, C. (2022). Subtitulado automático bilingüe: Una solución no tan sencilla. Panorama Audiovisual.Com.

Romero-Fresco, P. (2009). More haste less speed: Edited versus verbatim respoken subtitles. Vigo International Journal of Applied Linguistics, 6, 109–133.

Romero-Fresco, P. (2011). Subtitling through speech recognition: Respeaking. St. Jerome.

Romero-Fresco, P. (2016). Accessing communication: The quality of live subtitles in the UK. Language and Communication, 49, 56–69.

Romero-Fresco, P., & Martínez, J. (2015). Accuracy rate in live subtitling: The NER model. In J. Díaz-Cintas & R. Baños-Piñero (Eds.), Audiovisual translation in a global context: Mapping an ever-changing landscape (pp. 28–50). Palgrave MacMillan.

Romero-Fresco, P., & Alonso-Bacigalupe, L. (2022). An empirical analysis on the efficiency of five interlingual live subtitling workflows. Xlinguae, 2, 3–13.

Romero-Fresco, P., & Fresno, N. (2023, July 5-7). AI and live captioning: Comparing the quality of automatic and human live captions in English [Conference presentation]. Media for All 10 Conference, University of Antwerp, Belgium.

Stingray Group Inc. (2021). Cover letter and report to CRTC.

TLN (Telelatino Network Inc.). (2021). Cover letter and report to CRTC.




How to Cite

Romero-Fresco, P., & Fresno, N. . (2023). The accuracy of automatic and human live captions in English. Linguistica Antverpiensia, New Series – Themes in Translation Studies, 22.