A prominent privacy expert has warned others to ban Amazon's voice assistant Alexa in their bedroom.
Hannah Fry, a mathematician with expertise in the algorithms tech companies use, has confirmed people's worse fears that smart speakers are listening to their conversations.
The 35-year-old said she keeps Amazon's voice-activated assistant in downstairs rooms only and that families should consider doing the same, the Independent reports.
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Amazon has previously denied that its Echo devices are eavesdropping on people's conversations, but then admitted earlier this year that employees listen to customer voice recordings in order to improve speech recognition.
It was also revealed that recordings of personal moments were inadvertently caught up after the smart speaker was triggered by words that sounded similar to "Alexa".
However, Fry found out that her Amazon speaker had actually picked up conversations that were never directed at the voice assistant after requesting audio data from the company.
"I think there are some spaces in your home, like the bedroom and bathroom, which should remain completely private," she explained.
"This technology is activated by a trigger word [such as 'Alexa'] but it keeps recording for a short period afterwards. People accept that, but we should all spend more time thinking about what it means for us."
She added that a lot of senior business technology workers would not have so much as a smartphone in their bedroom.
"If a company is offering you a device with an internet-connected microphone at a low price, you have to think about that very carefully.
"I have both an Alexa and a Google voice-activated device and I regularly turn them both off. People really must set their own limits."
A report by news website Bloomberg suggested many users are unaware humans are listening in, with each staff member reviewing up to 1000 audio clips a day.
Teams had also shared recordings they found funny in internal chat rooms.
An Amazon spokesperson said: "To help improve Alexa, we manually review and annotate a small fraction of one per cent of Alexa requests.
"Access to data annotation tools is only granted to a limited number of employees who require them to improve the service, and our annotation process does not associate voice recordings with any customer identifiable information.
"Customers can opt-out of having their voice recordings included in the fraction of one per cent of voice recordings that get reviewed."