https://www.cnbc.com/2017/09/21/amazon-alexa-smart-glasses-to-use-bone-conduction-not-headphones.html

The days of wearing headphones for listening could soon be gone, because Amazon's planned smart glasses are set to use bone conduction to transmit sound through your skull, according to a report.

Amazon's Alexa assistant is set to power its smart glasses, the FT reported, and wearers will be able to hear Alexa's responses to questions via their frames, transmitted through people's skulls.