U.S. Senators Jeff Flake (R-AZ) and Chris Coons (D-Del.) have written to Amazon boss Jeff Bezos, demanding answers to 29 questions over privacy concerns relating to the company's Echo speaker range and its Alexa intelligent assistant.

Their concerns come after - and refer directly to - a recent incident in Portland, Oregon, where an Echo device mistakenly recorded a private conversation taking place in the same room, then sent it to a random contact of its owner.

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Written and sent to Bezos on June 15, the letter suggests Echo devices and the Alexa assistant "may share private consumer information that potentially puts Amazon users' privacy at risk."

Flake and Coons continue: "Recent events have demonstrated that it may take just a few words for Alexa to share with others personal information that the consumer would prefer - and would expect - to be kept private."

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Flake and Coons serve respectively as the chairman and ranking member of the Judiciary Subcommittee on Privacy, Technology and the Law.

They then cite the Oregon incident, stating how the couple who own the Echo smart speaker were unaware that its microphone had switched on (which happens when the device hears "Alexa"). A recording was sent to a random acquaintance of theirs.

The device did not malfunction, but simply misunderstood - on several consecutive occasions - what it had heard. That was the "Alexa" wake word, followed by what it thought was a request to send a message and then what it thought was the contact's name. Alexa then sent the message after mistakenly hearing it being permitted to do so.

The senators asked Amazon to change how Alexa works and added, "Without prompt and meaningful action, we expect that additional instances like the one summarized will happen again."

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They went on: "The increasing popularity of in-home, internet-connected devices and voice-activated technologies raises questions about the types of data they collect, store, and share, and the degree to which consumers control their personal information. Companies, like Amazon, that offer services through these devices must address these concerns by prioritizing consumer privacy and protecting sensitive personal information."

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They then ask Bezos 29 questions about how Echo speakers and the Alexa assistant work. They ask how many customer complaints Amazon has received "reporting that an Amazon Echo device has improperly interpreted a command."

The senators also ask how often Echo devices send voice data to Amazon's servers and how long Amazon stores it. You can read the letter and its questions in full here.

It is already known that Echo devices store everything they hear on Amazon's server until the user deletes each recording. These can be listened to at any time through the Alexa smartphone app, which lists them in reverse-chronological order. However, Amazon claims that deleting these will limit Alexa's ability to understand you more accurately in the future.

The company states: "When you use an Alexa device, we keep the voice recordings associated with your account to improve the accuracy of the results provided to you and to improve our services." Amazon also warns that deleting the recordings "may degrade your experience using the device."

How to listen to and delete everything Alexa has heard you say

Regarding the Oregon incident, Amazon said: "Echo woke up due to a word in background conversation sounding like "Alexa. Then, the subsequent conversation was heard as a 'send message' request. At this point, Alexa said out loud, 'To whom?' At this point, the background conversation was interpreted as a name in the customer's contact list. Alexa then asked, '[contact name], right?' Alexa then interpreted the background conversation as 'right'."

Check out The GearBrain, our smart home compatibility checker, to see which other compatible products work with Amazon Alexa.

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