IPA (International Phonetic Alphabet)
The IPA is a universal notation system that represents every distinct speech sound in every human language with a unique symbol.
The International Phonetic Alphabet (IPA) is a standardised notation system developed by linguists in 1888 to represent every distinct speech sound in every human language with a unique symbol. Each symbol corresponds to a single phoneme — "/p/" always means the /p/ sound regardless of how it's written in the source language. IPA is used by linguists, language teachers, speech therapists, dictionaries (for pronunciation guides), and TTS developers (for specifying exact pronunciation). Example IPA transcriptions: the English word "through" is /θruː/, the Hindi word "namaste" is /nəməsteː/, the Tamil word "vanakkam" is /ʋaɳakːam/. IPA can represent roughly 107 consonant symbols, 52 vowel symbols, and dozens of diacritic marks for length, stress, and nasalisation — covering the full range of sounds produced by humans. For Indian-language TTS, IPA is essential because native scripts (Devanagari, Tamil, Malayalam) carry ambiguity that IPA resolves — the same Devanagari character can represent slightly different phonemes depending on context, while IPA makes the underlying sound explicit.
How it works
IPA is organised by articulation — consonants are classified by place (where in the mouth the sound is made) and manner (how the airflow is constricted). Vowels are classified by tongue position (front/central/back, high/mid/low) and lip rounding. Indian-language-relevant IPA symbols include retroflex consonants (/ʈ/, /ɖ/, /ɳ/, /ɭ/), aspirated stops (/pʰ/, /tʰ/, /kʰ/), voiced aspirated (/bʱ/, /dʱ/, /gʱ/), nasal vowels (/ã/, /ẽ/), and dental-vs-retroflex distinctions. SSML uses IPA in the `<phoneme>` tag — `<phoneme alphabet="ipa" ph="ˈpuːnə">Pune</phoneme>` ensures the city is pronounced "Poo-nay". IPA transcriptions are also used in dictionary pronunciation guides and language-learning tools to show learners exactly how to produce a sound.
Examples
Dictionary use
"Through" written in IPA as /θruː/ — the /θ/ tells you it's the "th" sound in "think", not the "th" in "this" (/ð/).
TTS pronunciation override
<phoneme alphabet="ipa" ph="ˈbɛŋɡəluːru">Bengaluru</phoneme> — ensures proper pronunciation of the Indian city name in TTS output.
Multilingual comparison
Hindi "p" /p/ vs "ph" /pʰ/ vs "bh" /bʱ/ — IPA makes clear these are three distinct sounds, which the Devanagari script shows as प / फ / भ.
Why this matters for Indian-language TTS
IPA is particularly useful for Indian-language TTS because Indian scripts abstract over phonemic distinctions that IPA makes explicit. A Devanagari letter like "त" technically represents /t̪/ (dental /t/) — a different phoneme from English "t" (/t/ — alveolar). IPA is also essential when working across Indian scripts — the same phoneme /ʈ/ is written differently in Devanagari (ट), Tamil (ட), Malayalam (ട), and Bengali (ট), but IPA gives it one universal symbol.
Related terms
Phoneme
A phoneme is the smallest distinct sound unit in a language that can change word meaning — e.g., the…
SSML (Speech Synthesis Markup Language)
SSML is an XML-based markup standard that lets you control pronunciation, pacing, pauses, emphasis, …
Text-to-Speech (TTS)
Text-to-speech (TTS) is the technology that converts written text into spoken audio using synthesise…
Diacritic
A diacritic is a mark added to a base letter to modify its pronunciation, typically indicating accen…
Frequently Asked Questions
Do I need to know IPA to use TTS?
Where do I find IPA for a specific word?
Is IPA used in SSML for all TTS providers?
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