https://techcrunch.com/2018/09/20/alexa-learns-how-to-whisper/

Today’s big Amazon event was all about the hardware, but Amazon kicked things off with a few extra tricks. Among the cooler features rolling out for the smart assistant in the coming weeks is improved contextual understanding. One piece that’s coming in the next few weeks is the ability to understand when the user needs Alexa to be quiet.

The company demonstrated the command “Alexa, play a lullaby.” When whispered, the assistant will whisper back at the user and play a quiet song at a quiet volume. It’s not exactly a breakthrough feature, but it’s a clear demonstration of a lot of the work that’s been going on in the backend to make Alexa smarter and more conversational.