Speechify TTS plugin guide

Available inPython

Overview

This plugin allows you to use Speechify as a TTS provider for your voice agents.

Installation

Install the plugin from PyPI:

uv add "livekit-agents[speechify]~=1.8"

Authentication

The Speechify plugin requires a Speechify API key .

Set SPEECHIFY_API_KEY in your .env file.

Usage

Use Speechify TTS within an AgentSession or as a standalone speech generator. For example, you can use this TTS in the Voice AI quickstart.

from livekit.plugins import speechify

session = AgentSession(
   tts=speechify.TTS(
      model="simba-3.2",
      voice_id="dominic_32",
   )
   # ... llm, stt, etc.
)

Parameters

This section describes some of the available parameters. See the plugin reference for a complete list of all available parameters.

voice_idstringDefault: dominic_32

ID of the voice to use for synthesizing speech. The voice must support the selected model. Voice IDs with a _32 suffix belong to the simba-3.2 voice roster. Refer to list_voices() method in the plugin reference.

modelstringDefault: simba-3.2

ID of the model to use for generation. Use simba-3.2 for English voices or simba-3.0 for non-English voices. The legacy Simba 1.6 models, simba-english and simba-multilingual, are retired for new Speechify integrations. To learn more, see supported models .

languageLanguageCode

Language code for the input text. See supported languages for the full list.

loudness_normalizationboolean

Determines whether to normalize the audio loudness to a standard level. When enabled, loudness normalization aligns the audio output to the following standards: Integrated loudness: -14 LUFS True peak: -2 dBTP Loudness range: 7 LU If disabled, the audio loudness will match the original loudness of the selected voice, which may vary significantly and be either too quiet or too loud. Enabling loudness normalization can increase latency due to additional processing required for audio level adjustments.

text_normalizationboolean

Determines whether to normalize the text. If enabled, it will transform numbers, dates, etc. into words. For example, "55" is normalized into "fifty five". This can increase latency due to additional processing required for text normalization.

Customizing pronunciation

Speechify supports custom pronunciation with Speech Synthesis Markup Language (SSML), an XML-based markup language that gives you granular control over speech output. With SSML, you can leverage XML tags to craft audio content that delivers a more natural and engaging listening experience. To learn more, see SSML .

Transcription timing

Speechify TTS supports aligned transcription forwarding, which improves transcription synchronization in your frontend. Set use_tts_aligned_transcript=True in your AgentSession configuration to enable this feature. To learn more, see the docs.

Additional resources

The following resources provide more information about using Speechify with LiveKit Agents.

Python package

The livekit-plugins-speechify package on PyPI.

Plugin reference

Reference for the Speechify TTS plugin.

Speechify docs

Speechify docs.

Voice AI quickstart

Get started with LiveKit Agents and Speechify TTS.