To support speech adaptive cards has the speak property which contains information on how to create speech to play for the user.
The speech tag can be annotated using SSML markup. SSML gives you the ability control the speed, tone, inflection of the speech. It even allows you to stream audio or a render a TTS audio stream from your own service, giving you a great deal of customization.
There are 2 patterns for speak property usage by a host application:
- on delivery - When a card is delivered a client may opt to read the Speak property for the card to describe the card as a whole.
- on demand - In order to support a richer accessibility model the schema supports a speak tag per element.
This allows for clients to read each element to recipients with accessibility requirements.