Amazon staff listen to recordings of customer interactions with voice-based assistant Alexa to help train the artificial intelligence's responses, a report from Bloomberg has said.
The tech giant uses review teams around the world to analyse and annotate some recordings gathered from Amazon Echo smart speaker devices - with the interactions then used to improve the programming of the Alexa software.
The Alexa companion app, which is used to set up smart devices and manage settings linked to the assistant, keeps a log of interactions between users and the assistant, and can be listened to or deleted from within the app.
In a statement, Amazon confirmed that it did use some recordings as part of its work to improve Alexa's ability to understand human language and speech patterns, but had strict security systems in place to keep user data safe.
"We take the security and privacy of our customers' personal information seriously. We only annotate an extremely small sample of Alexa voice recordings in order to improve the customer experience," said a spokeswoman.
"For example, this information helps us train our speech recognition and natural language understanding systems, so Alexa can better understand your requests, and ensure the service works well for everyone.”
She added: “Employees do not have direct access to information that can identify the person or account as part of this workflow.
"All information is treated with high confidentiality and we use multi-factor authentication to restrict access, service encryption, and audits of our control environment to protect it."
The help page of the Amazon website dedicated to Alexa states that Amazon may "use your requests to Alexa to train our speech recognition and natural language understanding systems", explaining that the more data used to train these systems, the better the voice assistant is able to work.
It also confirms that the company "associate your requests with your Amazon account to allow you to review your voice recordings, access other Amazon services ... and to provide you with a more personalised experience".
According to research from last year, one in 10 people has one or more smart speakers in their home, with Amazon's range of Echo smart devices the market leader.