It's said that a team of both in-house and contracted workers review recordings in a bid to improve the virtual assistant, and while this could be a boost for the device, it also raises privacy issues.
According to a report by Bloomberg, employees - listening to up to 1,000 clips a shift - sometimes encounter dangerous material.
The website claims: "Two of the workers said they picked up what they believe was a sexual assault. When something like that happens, they may share the experience in the internal chat room as a way of relieving stress."
While Amazon has confirmed it monitors Alexa audio recordings in order to improve the product, it hasn't outright admitted to using humans to listen.
The company added in a statement: "We take the security and privacy of our customers' personal information seriously.
"We only annotate an extremely small number of interactions from a random set of customers in order to improve the customer experience.
"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."