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# Speech synthesis

Configure voices to speak strings of text.

## Discussion

The Speech Synthesis framework manages voice and speech synthesis, and requires two primary tasks:

Create an [`AVSpeechUtterance`](/documentation/AVFAudio/AVSpeechUtterance) instance that contains the text to speak. Optionally, configure speech parameters, such as voice and rate, for each utterance.

```swift
// Create an utterance.
let utterance = AVSpeechUtterance(string: "The quick brown fox jumped over the lazy dog.")

// Configure the utterance.
utterance.rate = 0.57
utterance.pitchMultiplier = 0.8
utterance.postUtteranceDelay = 0.2
utterance.volume = 0.8

// Retrieve the British English voice.
let voice = AVSpeechSynthesisVoice(language: "en-GB")

// Assign the voice to the utterance.
utterance.voice = voice
```

Pass the utterance to an [`AVSpeechSynthesizer`](/documentation/AVFAudio/AVSpeechSynthesizer) instance to produce spoken audio.

```swift
// Create a speech synthesizer.
let synthesizer = AVSpeechSynthesizer()

// Tell the synthesizer to speak the utterance.
synthesizer.speak(utterance)
```

Optionally, use the speech synthesizer instance to control or respond to ongoing speech; for example, assign its [`delegate`](/documentation/AVFAudio/AVSpeechSynthesizer/delegate) to receive speech event notifications.

## Topics

### Spoken text attributes

[`AVSpeechUtterance`](/documentation/AVFAudio/AVSpeechUtterance)

An object that encapsulates the text for speech synthesis and parameters that affect the speech.

[`AVSpeechSynthesisVoice`](/documentation/AVFAudio/AVSpeechSynthesisVoice)

A distinct voice for use in speech synthesis.

### Speech synthesis controls

[`AVSpeechSynthesizer`](/documentation/AVFAudio/AVSpeechSynthesizer)

An object that produces synthesized speech from text utterances and enables monitoring or controlling of ongoing speech.

### Speech synthesis audio unit

[`AVSpeechSynthesisProviderAudioUnit`](/documentation/AVFAudio/AVSpeechSynthesisProviderAudioUnit)

An object that generates speech from text.


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