https://www.theguardian.com/technology/2018/may/24/amazon-alexa-recorded-conversation

The company, which has insisted its Echo devices aren’t always recording, has confirmed the audio was sent

No matter how suspicious it has seemed that Amazon is encouraging us to put listening devices in every room of our homes, the company has always said that its Echo assistants are not listening in or recording conversations. Over and over again, company spokespeople have promised that they only start recording if someone says the wake word: “Alexa”.