https://www.theverge.com/circuitbreaker/2018/10/18/17995092/amazon-alexa-whisper-mode-guard-context-aware

Amazon’s Alexa is getting Whisper Mode today, so everyone can start using their indoor voices. The feature, which allows the voice assistant to receive whisper commands and whisper back in reply, is now rolling out to users in the US, but it’s currently only available in English. It’ll most likely come in handy for parents who can whisper to Alexa to play a lullaby and for generally keeping noise to a minimum as to not wake a sleeping partner or baby.

We first saw previews of the Whisper Mode feature when Amazon opened up its Speech Synthesis Markup Language to developers last year. It was introduced as part of the company’s efforts to make Alexa sound more humanlike, allowing it to whisper, vary its speaking speed, and add pauses. A Verge reader gave us a demonstration of what it sounded like then: