Translation

session.translation turns spoken speech into translated text. Register a handler for the language pair you care about and results start arriving; the SDK handles the subscription for you.

session.translation.to("es", (data) => {
  if (data.isFinal) {
    session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: data.text}]);
  }
});

Translation needs the MICROPHONE permission in your manifest. Without it the phone drops the subscription and no events arrive. The rejection is silent: there is no error event, your handler just never fires.

Results

Each event is a TranslationData:

Field	Type	Notes
`text`	`string`	The translated text so far.
`isFinal`	`boolean`	`false` for interim results that keep updating, `true` once the utterance is settled.
`sourceLanguage`	`string`	Language the speech was recognized in.
`targetLanguage`	`string`	Language `text` was translated into.
`originalText`	`string?`	Source-language text of the same utterance, when the provider supplies it.
`utteranceId`	`string?`	Stable id correlating interim and final results of one utterance.
`speakerId`	`string?`	Speaker id when the provider reports diarization.

Interim results stream as the user speaks and get replaced; wait for isFinal if you only want settled text. Use utteranceId to match an interim result to the final one that supersedes it.

Choosing what to listen for

Three methods select which translations reach your handler. They differ only in how they pin the source and target language.

Method	Listens for
`on(handler)`	Every translation event, any source, any target.
`to(target, handler)`	Any source, translated to `target`. Pass an array of targets to fan one handler across several.
`fromTo(source, target, handler)`	A specific `source` to `target` pair. Pass an array for `target` to fan one source across several targets.

Each returns an unsubscribe function. source and target are language tags (for example "en", "es").

// Any language the user hears, translated to Spanish.
session.translation.to("es", handler);

// Several targets at once, one handler.
session.translation.to(["es", "fr"], handler);

// A specific direction: English speech to Spanish text.
session.translation.fromTo("en", "es", handler);

// One source fanned across multiple targets.
session.translation.fromTo("en", ["es", "fr"], handler);

on() is the broad case. It registers cheaply on your side but asks the cloud to fan every active pair out to you, so reach for to or fromTo once you know the language(s) you want. When the provider supplies originalText, you can show the source and the translation together:

session.translation.to("es", (data) => {
  if (data.originalText) {
    session.display.showDoubleTextWall(data.originalText, data.text);
  } else {
    session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: data.text}]);
  }
});

forLanguagePair(fromLang, toLang, handler) is a deprecated alias for fromTo(source, target, handler). Use fromTo in new code; the alias will be removed in a future release.

Cleaning up

Every subscription returns an unsubscribe function. stop() tears down every subscription this module owns at once:

const off = session.translation.to("es", handler);
off();                      // drop this one

session.translation.stop(); // drop all of them

session.translation.hasPermission tells you whether MICROPHONE is declared in your manifest. It does not tell you whether the user granted the OS prompt: if they denied it, your handler simply never fires. See Permissions.

Translation gives you translated text. For the untranslated transcript in the spoken language, use session.transcription. Subscribing to one does not subscribe you to the other.

Getting Started

Core Concepts

UI Layer

Display

Audio & Speech

Sensors & Input

Camera

Phone & System

Data

Reference

Results

Choosing what to listen for

Cleaning up

​Results

​Choosing what to listen for

​Cleaning up

Results

Choosing what to listen for

Cleaning up