Glossary
Diacritics
Diacritics 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.
Updated October 17, 20266 cited facts, each traced to its source
Also called accent marks.
Diacritics are marks added to a letter to show how it sounds or which word it forms. The acute accent in é, the tilde in ñ and the dots that mark vowels in Arabic are all diacritics. In many languages a diacritic changes the word itself, not only its pronunciation, so leaving it out can produce a different word.
A diacritic can turn one word into another
In Spanish, si means "if" and sí means "yes". The only difference is the accent on the vowel. Dictation that writes "si" when you said "sí" produces a real word with the wrong meaning, and a spell checker will not flag it. The same is true of tu ("your") and tú ("you").
In Hebrew, most vowels are written as diacritics, so the pronunciation of a word is left underspecified when they are missing 1. Arabic works the same way: most people write and type Arabic text without its diacritics 2.
Speech tools often leave diacritics out
A speech recognizer hears sounds and has to decide which written form to produce. For Spanish, one of the most common errors of automatic speech recognition is the omission of the diacritical tilde 3. The sounds of "si" and "sí" are the same, so the choice depends on the sentence around the word, which is the same problem as homophones.
For Arabic, the problem starts in the training data. Most Arabic speech corpora and speech models are undiacritized, because the marks are often omitted from the text they learn from 4. A 2023 study found that diacritizing inside the speech model outperformed diacritizing the text afterward, especially when the model was fine-tuned on manually diacritized transcripts 5. The output of a model trained without marks often lacks them too.
Typing a diacritic takes an extra step
When you type rather than dictate, a diacritic usually needs one extra step. On a Mac, pressing and holding a letter key opens a menu of the accent marks you can enter with that letter 6. Dictation has no such menu, so after you dictate you may need to add a missing mark by hand. Proofreading catches these gaps. Our guide to Spanish speech to text covers how accent marks come out in dictated Spanish, and the question on whether Spanish dictation adds accent marks automatically answers the most common doubt.
Why diacritics matter for dictation
A dictated sentence can sound correct to a listener and still be wrong on the page. Check every word that carries a mark in a draft, especially short words such as "si" and "tu", and names. Our overview of dictation languages lists which languages each tool supports, but support for a language does not guarantee that every mark will be written.
Related terms
- Accent: how a speaker's pronunciation sounds, which is a different idea from the marks on the page.
- Pinyin: the romanization of Mandarin, which uses tone diacritics.
- Transliteration: writing a language in another script, which can drop marks.
- Modern Standard Arabic (MSA): the formal Arabic used in news and official writing.
Guides and questions that cover it
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.
- 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.
- Right-to-left (RTL) scriptA 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.
- 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
- Spanish Speech to Text and Talk to TextGuide
- Arabic Speech to Text and Right-to-Left DictationGuide
- Does Spanish dictation add accent marks automatically?Question
- Does speech to text understand Arabic dialects?Question
- How do you transcribe Arabic or Hebrew audio to text?Question
- Modern Standard Arabic (MSA)Glossary
- PinyinGlossary