This is an opt-in functionality, so it must be enabled in the Alexa Settings app.
He also said that many customers have expressed a desire for more time before Alexa responds to requests.
The longer wait time should be useful for garden-variety Alexa users, but it will be a major boon to those with a speech impairment.
If you are planning on making use of the feature, there are plenty of useful commands you can try out with your favorite Alexa device.