MENLO PARK, California — The world’s largest social media platform with over 2.3 billion monthly active users, Facebook, has admitted it uses an external company to listen to audio messages sent between users in an attempt to improve its voice recognition systems.

In a report by Bloomberg, Facebook paid contractors to transcribe audio messages sent between users. Those contractors did not know who the audio was from and how Facebook obtained it.

In response to the report, Facebook said users who had their audio transcribed confirmed this option in its Messenger app, and that the practice had since stopped.

This marks the fourth tech company to come forward following Amazon, Apple and Google whom all have admitted that real humans were listening to and transcribing audio from voice services from Alexa, Siri and Google Home respectively, all claiming the aim was to improve voice recognition.

“Much like Apple and Google, we paused human review of audio more than a week ago,” the company said.

Bloomberg noted that in its data-use policy, there is no mention of humans interacting with the audio.

The policy only mentions “vendors and service providers who support our business” by “analyzing how our products are used”.

The companies have since said they have stopped doing this as privacy organisations raised concerns over the practice.