Text-to-Speech (Streamed File) | Hume API

Authentication

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

Request

This endpoint expects an object.

utterances
list of objects Required
A list of Utterances to be converted to speech output.

An Utterance is a unit of input for Octave, 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.

Show 5 properties

context
object or null Optional
Utterances to use as context for generating consistent speech style and prosody across multiple requests. These will not be converted to speech output.

Show 2 variants

format
object Optional
Defaults to {"type":"mp3"}
Specifies the output audio file format.

Show 3 variants

include_timestamp_types
list of enums Optional
Defaults to []
The set of timestamp types to include in the response. Only supported for Octave 2 requests.

Allowed values: word, phoneme

num_generations
integer Optional
1-5 Defaults to 1
Number of audio generations to produce from the input utterances.

Using num_generations enables faster processing than issuing multiple sequential requests. Additionally, specifying num_generations allows prosody continuation across all generations without repeating context, ensuring each generation sounds slightly different while maintaining contextual consistency.

split_utterances
boolean Optional
Defaults to true
Controls how audio output is segmented in the response.

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_headers
boolean Optional
Defaults 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).

temperature
double or null Optional
0.1-1 Sampling temperature for the speech generation model. Higher values increase variation; lower values increase consistency.

This is an experimental parameter. It is recommended to use the default values for most use cases.

Defaults when omitted:

version
enum Optional
Selects the Octave model version used to synthesize speech for this request. If you omit this field, Hume automatically routes the request to the most appropriate model. Setting a specific version ensures stable and repeatable behavior across requests.

Use 2 to opt into the latest Octave capabilities. When you specify version 2, you must also provide a voice. Requests that set version: 2 without a voice will be rejected.

For a comparison of Octave versions, see the Octave versions section in the TTS overview.

Allowed values: 1, 2

instant_mode
boolean Optional
Defaults 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.

Response

OK

Errors

422
Unprocessable Entity Error