Glossary
Right-to-left (RTL) script
A right-to-left (RTL) script is a writing system, such as Arabic, Hebrew, Persian or Urdu, whose letters run from right to left. Text that mixes these letters with digits or Latin words is bidirectional, so software needs a specific algorithm to order and display it.
Updated October 17, 20264 cited facts, each traced to its source
Also called RTL, bidirectional text.
A right-to-left (RTL) script is a writing system whose letters run from right to left across the line. Arabic, Hebrew, Persian and Urdu are common examples. The term describes the direction of the letters, not the direction of the words in a sentence, and it is written RTL for short. Text that mixes an RTL script with left-to-right material, such as English words or numbers, is called bidirectional text.
Each character has a direction that the software must follow
The Unicode standard gives every character a bidirectional type. The types left-to-right and right-to-left are called strong types 1. Arabic and Hebrew letters carry right-to-left types, and Latin letters carry left-to-right types. Digits and punctuation are weaker, so their direction depends on the characters around them.
Mixed text is bidirectional, which makes it harder to display and edit
Whenever right-to-left scripts use digits that are written from left to right, the text is actually bidirectional, a mixture of right-to-left and left-to-right text 2. The same is true when an English brand name or a phone number appears inside an Arabic sentence.
Neutral characters, such as spaces and punctuation, generally take the direction of the surrounding text 3. That rule explains a common surprise. A comma or full stop placed between an Arabic word and an English word can end up on a side you did not expect, because the software reads its direction from whichever side it is attached to.
A concrete example: a price inside an Arabic sentence
Suppose you dictate an Arabic sentence that ends with a price written as "25 dollars". The digits 25 are written left to right inside a line that otherwise runs right to left. The number is stored in the order you spoke it, but on screen it can sit in the middle of the sentence in an order that looks reversed, and the arrow keys may seem to skip through it in a strange sequence. The text is correct. The display follows the bidirectional rules.
Why it matters for dictation and typing
Dictation engines output text in the order it was spoken. The app and the text engine then decide how to show it. If a sentence looks backward after dictation, check the paragraph direction and the characters at the edges of the mixed part before you retype anything. Our guide to Arabic speech to text and right-to-left dictation covers the common cases, and the question on RTL dictation and text that appears backwards gives the short fixes.
Written Arabic also adds a recognition problem. Most people write and type Arabic without diacritics, the short vowel marks. The 2023 Interspeech paper notes that most speech corpora and Arabic ASR models are undiacritized, because diacritics are often omitted 4. A dictation tool therefore usually returns text without those marks. The output is the normal written form, not a mistake.
Related terms
- Locale: the language and region setting that turns on the right script and its conventions.
- Dialect: Arabic has many spoken dialects, and they are written in the same script.
- Automatic speech recognition (ASR): the process that produces the text before display.
- Text insertion: the step that places recognized text into the app at the cursor.
Guides and questions that cover it
- Guide: Arabic speech to text and right-to-left dictation.
- Guide: dictation languages, and what each app and device supports.
- Question: RTL dictation and text that appears backwards.
- Question: which Arabic dialects does speech to text handle?
- Overview: dictation languages, accents and voice translation.
Evidence
Every number on this page, with where it comes from. Open a fact to see the exact words in its source.
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Related terms
- Dictation Languages, Accents and Voice TranslationThe topic this term belongs to
- AccentAn accent is the way a speaker pronounces a language, shaped by where they grew up, their first language or their community. Accents change pronunciation, not vocabulary, and speech recognition error rates can differ sharply from one accent to another.
- Character error rate (CER)Character error rate (CER) is the number of character insertions, substitutions and deletions needed to turn a recognizer's output into the correct text, divided by the number of characters in the correct text. It is the usual measure where words are not separated by spaces.
- Code-switchingCode-switching is the habit of moving between two or more languages within a conversation or a single sentence. Speech recognizers built around one language often misread the switched words, so mixed speech is harder to dictate than speech in one language.
- DiacriticsDiacritics are marks added to a letter, such as the acute accent in é, the tilde in ñ or the vowel marks in Arabic, that change how a letter sounds or which word it spells. Speech tools and everyday writers often leave them out, so a dictated word can come out spelled differently from what you meant.
- DialectA dialect is a regional or social variety of a language, with its own vocabulary, grammar and pronunciation. Speech recognition is usually less accurate on dialects than on the standard form, because labeled training data for dialects is often scarcer.
- Input method editor (IME)An input method editor (IME) is software that supports text input for characters that cannot be typed easily on a standard keyboard, such as many East Asian characters. Speech input can also be an input method, and Android allows only one input method to be enabled at a time.
- LocaleA locale is a language combined with a region, and sometimes a script, such as en-GB for English as used in the United Kingdom. Dictation and speech settings use locales because the same language can differ in spelling, punctuation and speech patterns from one region to another.
- Low-resource languageA low-resource language is one with little digital speech and text data for training speech recognition and other language tools. There is no fixed cutoff, and a language can be well resourced for one task and poorly resourced for another.
- Modern Standard Arabic (MSA)Modern Standard Arabic (MSA), also called Fusha, is the standardized form of Arabic used in writing and formal speech, such as news broadcasts and official documents. Speakers use regional dialects in everyday conversation, and speech tools recognize formal Arabic more accurately than dialect speech.
- Non-native speechNon-native speech is speech in a language that is not the speaker's first language, often called L2 speech or foreign-accented speech. Recognizers can transcribe read non-native English well, but they handle hesitations, repetitions and revisions differently, and results depend on the system.
- PinyinPinyin, also called Hanyu Pinyin, is the system that spells Mandarin Chinese syllables with the Latin alphabet and marks the tones with diacritics. People type Chinese by spelling the sound in Pinyin and choosing the character they want, and speech tools must choose among characters that share one Pinyin spelling.
- Speech translationSpeech translation converts speech in one language into the same meaning in another language, as text or as synthesized speech. Most systems first recognize the speech and then translate the text, so a recognition error carries into the translation.
Pages that use this term
- Dictation Languages, Accents and Voice TranslationTopic
- Arabic Speech to Text and Right-to-Left DictationGuide
- Dictation Punctuation Commands in Other LanguagesGuide
- Transcribe and Translate Audio in Other LanguagesGuide
- How do you transcribe Arabic or Hebrew audio to text?Question
- How do you transcribe Tamil, Urdu, Bengali or other South Asian audio?Question
- How do you voice type in Arabic?Question