CompositeVoice

The CompositeVoice class allows you to combine different voice providers for text-to-speech and speech-to-text operations. This is particularly useful when you want to use the best provider for each operation - for example, using OpenAI for speech-to-text and PlayAI for text-to-speech.

CompositeVoice supports both Mastra voice providers and AI SDK model providers

Constructor Parameters

config:

object

Configuration object for the composite voice service

config.input?:

MastraVoice | TranscriptionModel

Voice provider or AI SDK transcription model to use for speech-to-text operations. AI SDK models are automatically wrapped.

config.output?:

MastraVoice | SpeechModel

Voice provider or AI SDK speech model to use for text-to-speech operations. AI SDK models are automatically wrapped.

config.realtime?:

MastraVoice

Voice provider to use for real-time speech-to-speech operations

Methods

speak()

Converts text to speech using the configured speaking provider.

input:

string | NodeJS.ReadableStream

Text to convert to speech

options?:

object

Provider-specific options passed to the speaking provider

Notes:

• If no speaking provider is configured, this method will throw an error
• Options are passed through to the configured speaking provider
• Returns a stream of audio data

listen()

Converts speech to text using the configured listening provider.

audioStream:

NodeJS.ReadableStream

Audio stream to convert to text

options?:

object

Provider-specific options passed to the listening provider

Notes:

• If no listening provider is configured, this method will throw an error
• Options are passed through to the configured listening provider
• Returns either a string or a stream of transcribed text, depending on the provider

getSpeakers()

Returns a list of available voices from the speaking provider, where each node contains:

voiceId:

string

Unique identifier for the voice

key?:

value

Additional voice properties that vary by provider (e.g., name, language)

Notes:

• Returns voices from the speaking provider only
• If no speaking provider is configured, returns an empty array
• Each voice object will have at least a voiceId property
• Additional voice properties depend on the speaking provider

Usage Examples

Using Mastra Voice Providers

import { CompositeVoice } from "@mastra/core/voice";
import { OpenAIVoice } from "@mastra/voice-openai";
import { PlayAIVoice } from "@mastra/voice-playai";

// Create voice providers
const openai = new OpenAIVoice();
const playai = new PlayAIVoice();

// Use OpenAI for listening (speech-to-text) and PlayAI for speaking (text-to-speech)
const voice = new CompositeVoice({
  input: openai,
  output: playai,
});

// Convert speech to text using OpenAI
const text = await voice.listen(audioStream);

// Convert text to speech using PlayAI
const audio = await voice.speak("Hello, world!");

Using AI SDK Model Providers

You can pass AI SDK transcription and speech models directly to CompositeVoice:

import { CompositeVoice } from "@mastra/core/voice";
import { openai } from "@ai-sdk/openai";
import { elevenlabs } from "@ai-sdk/elevenlabs";

// Use AI SDK models directly - they will be auto-wrapped
const voice = new CompositeVoice({
  input: openai.transcription('whisper-1'),      // AI SDK transcription
  output: elevenlabs.speech('eleven_turbo_v2'),  // AI SDK speech
});

// Works the same way as with Mastra providers
const text = await voice.listen(audioStream);
const audio = await voice.speak("Hello from AI SDK!");

Mix and Match

You can combine Mastra providers with AI SDK models:

import { CompositeVoice } from "@mastra/core/voice";
import { PlayAIVoice } from "@mastra/voice-playai";
import { groq } from "@ai-sdk/groq";

const voice = new CompositeVoice({
  input: groq.transcription('whisper-large-v3'),  // AI SDK for STT
  output: new PlayAIVoice(),                       // Mastra for TTS
});