The update has just been released to US users currently, and only in English. More countries and languages will no doubt be added in the coming months.

Amazon has rolled out a Whisper Mode update to the Amazon Alexa voice-assistant, users in the US can now whisper commands to their Alexa and it will whisper back.
It has reported by numerous outlets that the update is allegedly in response to complaints about the noise level of Alexa especially to parents with younger children. It’s likely that this is where it will be most useful, especially at bedtime.
However, it is part of a larger to plan to make Alexa more intelligent and humanlike by making it more contextually aware and able to recognise conversational cues.
The Whisper Mode was previously featured at Amazon’s hardware event last month, and in a blog post about Alexa’s expanding AI-capabilities, along with Alexa varying its speaking speed, and adding in pauses.
According to Rohit Prasad, Alexa AI vice president and head scientist, Alexa can “automatically learn the features of audio signals useful for detecting sound events or whispered speech.”
Whisper Mode is powered by the same machine learning network that’s used for Alexa Guard, which can recognise “smoke alarms, carbon monoxide alarms, and glass breaking to turn Alexa into a home security system.”