Text-to-Speech (TTS)

Text-to-Speech (Streamed File)

Streams synthesized speech using the specified voice. If no voice is provided, a novel voice will be generated dynamically. Optionally, additional context can be included to influence the speech's style and prosody.

Authentication

X-Hume-Api-Keystring
API Key authentication via header

Request

This endpoint expects an object.
utteranceslist of objectsRequired
A list of **Utterances** to be converted to speech output. An **Utterance** is a unit of input for [Octave](/docs/text-to-speech-tts/overview), and includes input `text`, an optional `description` to serve as the prompt for how the speech should be delivered, an optional `voice` specification, and additional controls to guide delivery for `speed` and `trailing_silence`.
contextobject or nullOptional
Utterances to use as context for generating consistent speech style and prosody across multiple requests. These will not be converted to speech output.
formatobjectOptional
Specifies the output audio file format.
include_timestamp_typeslist of enumsOptional
The set of timestamp types to include in the response.
Allowed values:
num_generationsintegerOptional>=1<=5Defaults to 1
Number of generations of the audio to produce.
split_utterancesbooleanOptionalDefaults to true
Controls how audio output is segmented in the response. - When **enabled** (`true`), input utterances are automatically split into natural-sounding speech segments. - When **disabled** (`false`), the response maintains a strict one-to-one mapping between input utterances and output snippets. This setting affects how the `snippets` array is structured in the response, which may be important for applications that need to track the relationship between input text and generated audio segments. When setting to `false`, avoid including utterances with long `text`, as this can result in distorted output.
strip_headersbooleanOptionalDefaults to false

If enabled, the audio for all the chunks of a generation, once concatenated together, will constitute a single audio file. Otherwise, if disabled, each chunk’s audio will be its own audio file, each with its own headers (if applicable).

versionenumOptional
The version of the Octave Model to use. 1 for the legacy model, 2 for the new model.
Allowed values:
instant_modebooleanOptionalDefaults to true
Enables ultra-low latency streaming, significantly reducing the time until the first audio chunk is received. Recommended for real-time applications requiring immediate audio playback. For further details, see our documentation on [instant mode](/docs/text-to-speech-tts/overview#ultra-low-latency-streaming-instant-mode). - A [voice](/reference/text-to-speech-tts/synthesize-json-streaming#request.body.utterances.voice) must be specified when instant mode is enabled. Dynamic voice generation is not supported with this mode. - Instant mode is only supported for streaming endpoints (e.g., [/v0/tts/stream/json](/reference/text-to-speech-tts/synthesize-json-streaming), [/v0/tts/stream/file](/reference/text-to-speech-tts/synthesize-file-streaming)). - Ensure only a single generation is requested ([num_generations](/reference/text-to-speech-tts/synthesize-json-streaming#request.body.num_generations) must be `1` or omitted).

Response

OK

Errors