ON MORE than one occasion during Mark Zuckerberg’s congressional grilling this week he was asked if Facebook secretly listens to people through their phone to target them with ads.

The Facebook CEO appeared pleased to be able to confirm such an idea as a conspiracy theory and assuage the concerns of senators that the company engages in such a thing.

But that is exactly what other tech firms are trying to do.

Earlier this month it was reported that Amazon filed a “voice sniffing” patent last year to eavesdrop on conversations, looking for certain words.

Currently the voice activated speaker is only supposed to be triggered by its name. Once a user says “Hey Alexa” it begins sucking in all audio around it so it can respond to commands.

Amazon keeps all that data but it is reportedly thinking about taking things a step further.

Amazon says it can use advanced artificial intelligence that would allow the device to listen to a conversation and analyse it for certain words that are said.

Theoretically, if you’re talking to your friend about a new video game that you’re really enjoying, the little smart speaker will file that nugget of information away.

A “voice sniffer algorithm” is what the Amazon patent labelled the technology.

It would use trigger words such as “like”, “love” and “hate” to build profiles on users to better target them with advertising.

“The more words they collect, the more the company gets to know you,” Daniel Burrus, a US tech analyst told America’s ABC.

By building a profile of key words and topics discussed by owners of the smart speaker, Amazon hopes it can learn even more about our tastes and desires.

“The identified keywords can be stored and/or transmitted to an appropriate location accessible to entities such as advertisers or content providers who can use the keywords to attempt to select or customise content that is likely relevant to the user,” the patent said.

The data could also be made available to friends of the user for gift buying, according to the patent.

Tech companies file huge amount of patents each year so any given patent should not be taken as a sign of genuine intention. For instance, last year Amazon filed more than 1960 patents, a majority of which were granted.

According to the ABC, as of earlier this month, this particular patent had not yet been awarded by the US patent office.