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

input?:

MastraVoice | TranscriptionModel

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

output?:

MastraVoice | SpeechModel

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

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 a realtime provider is configured, it handles the call; otherwise the speaking provider is used
• Throws a MastraError only when neither a realtime nor a speaking provider is configured
• Options are passed through to the provider that handles the call
• Returns a stream of audio data, or void when a realtime provider handles the call

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 a realtime provider is configured, it handles the call; otherwise the listening provider is used
• Throws a MastraError only when neither a realtime nor a listening provider is configured
• Options are passed through to the provider that handles the call
• Returns a string or a stream of transcribed text, depending on the provider, or void when a realtime provider emits results through events

getSpeakers()

Returns a list of available voices from the realtime provider, or from the speaking provider when no realtime provider is configured, 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 realtime provider when one is configured, otherwise from the speaking provider
• Throws a MastraError when neither a realtime nor a speaking provider is configured
• Each voice object will have at least a voiceId property
• Additional voice properties depend on the 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
})