Generative voices - Amazon Polly
Available generative voicesFeature and Region compatibilityUsing the Generative engine on the console

Generative voices

Amazon Polly's generative text-to-speech (TTS) engine offers the most human-like, emotionally engaged, and adaptive conversational voices available for the use via the Amazon Polly console.

The Generative engine is the largest Amazon Polly TTS model to-date. It deploys a billion-parameter transformer that converts raw text into speech codes, followed by a convolution-based decoder that converts these speech codes into waveforms in an incremental, streamable manner. This method shows the widely-reported emergent abilities of Large Language Models (LLMs) when trained on increasing volumes of publicly available and proprietary data comprising a variety of voices, languages, and styles.

The Generative engine creates synthetic speech which is emotionally engaged, assertive, and highly colloquial in a way that is remarkably similar to a human voice. You can use these voices as a knowledgeable customer assistant, a virtual trainer, or an advertiser with a near-human synthetic speech.

Note

The state-of-the-art technology underlying these voices falls within the paradigm of generative AI for language and voice modelling. A side effect of the technology is that any updates to the training data and the model could result in slight variations to the way the voices sound, even in case when their overall quality improves with model updates. This could have an impact on use cases with different content parts synthesized over a long time period – for example, a season of podcasts.

Available generative voices

Amazon Polly currently offers two female and one male English voice in a generative variant. These generative voices are also available in a conversational NTTS variant.

Language Language code Name/ID Gender

1

English (UK)

en-GB

Amy

Female

2

English (US)

en-US

Matthew

Ruth

Male

Female
Note

Generative voices cost is specified on the Amazon Polly pricing information page.

Feature and Region compatibility

Amazon Polly generative voices are available in the following Region:

  • US East (N. Virginia): us-east-1

  • Europe (Frankfurt): eu-central-1

  • Other Regions are not available

The following features are supported for generative voices:

  • Real-time and asynchronous speech synthesis operations.

  • Newscaster speaking style is not supported in the Generative engine.

  • Many (but not all) SSML tags are supported by Amazon Polly. For more information about NTTS-supported SSML tags, see Supported SSML tags

  • As with standard voices, you can choose from various sampling rates to optimize the bandwidth and audio quality for your application. Valid sampling rates for standard and neural voices are 8 kHz, 16 kHz, 22 kHz, or 24 kHz. The default for standard voices is 22 kHz. The default for generative voices is 24 kHz. Amazon Polly supports MP3, OGG (Vorbis), and raw PCM audio stream formats.

  • The new Amazon Polly generative voices have 100ms latency.

Support for generating speech marks is currently not available.

Note

In the unlikely event of model hallucination, (and with the Generative engine's model behavior of rendering the speech token by token) an imposed emergency stop mechanism is in place. The built-in mechanism stops the model from rendering speech any further. This safety feature is based on data analysis where the model has the potential to hallucinate, usually at the end of the sentence.

There could be cases where the model thinks it is going to hallucinate and then might end up cutting a word during a generation step, thus rendering half the word. This could potentially generate inappropriate results.

Using the Generative engine on the console

You can access Amazon Polly generative voices through the Amazon Polly console or AWS CLI. From the console, select the Generative engine, then select a corresponding generative voice from the list to hear the synthesized speech in that voice. You can also explore generative voices with the SynthesizeSpeech and StartSpeechSynthesisTask API operations. For the API operations, you can specify the engine and the name of the voices in the API request. For quick-start getting started code examples using Python, see Python examples.

To use the generative engine on the console

  1. Open the Amazon Polly console at https://console.aws.amazon.com/polly/.

  2. From the Amazon Polly console, choose the Generative engine.

  3. Choose the desired voice from the voice dropdown menu.

  4. Generate TTS audio with text of your choice.

Note

Generative voices can also be used with the SynthesizeSpeech and StartSpeechSynthesisTask API operations. For the API operations, customers can specify the engine and the name of the voices in the API request. You can find more quick-start code samples here.