A summary of evidence[1]

Same Language Subtitling (SLS) is the idea of subtitling audio-visual content in the ‘same’ language as the audio. Word for word, what you hear is what you read. SLS was first coined in 1996 to promote reading literacy in a multilingual country like India with 23 official languages and 700+ dialects (Kothari, 1998). SLS and captioning are overlapping concepts but not the same. Captioning can be transliteration or translation. SLS is strictly transliteration.[2]