The system would pick up scanner beeps, rustling bags and conversations.

Walmart this week was awarded a US patent for a new listening system for its stores that could raise serious privacy concerns from its shoppers and workers.

According to the filing, the system would capture a variety of sounds in the store to figure out employees’ performance and effectiveness at checkout.

For instance, the system can be used to capture beeps produced by a scanner and the rustling of bags at checkout to find out the number of items in a transaction or even the number of bags used.

More alarmingly, the patent mentions that the system could be used to listen to guests’ conversations to determine the lengths of checkout lines.

“Additionally, the sound sensors can capture audio of conversations between guests and an employee stationed at the terminal,” the patent states. “The system can process the audio of the conversation to determine whether the employee stationed at the terminal is greeting guests.”

The new concept hasn’t been implemented in Walmart stores and Walmart didn’t say whether it ever will be.

The patent comes at a time of heightened concern about user privacy and data, following Facebook’s Cambridge Analytica scandal. Shoppers worried about being recorded in stores may opt to avoid those locations or perhaps shop online instead.

The patent also points to efforts by retailers, including Walmart, to upgrade their technology to keep up with Amazon, the leader in e-commerce. Walmart is already developing a handful of new technologies for its stores, including shelf-scanning robots.

“This patent is a concept that would help us gather metrics and improve the checkout process by listening to sounds produced by the bags, carts and cash registers and not intended for any other use,” the company said in a statement. “We file patents frequently but that doesn’t mean the patents will actually be implemented. We’re always thinking about new concepts and ways that will help us further enhance how we serve customers.”