The Amazon Echo smart speaker has made a splash in households thanks to its voice assistant Alexa, but it's also making headlines in the news after becoming a potentially vital piece of evidence in a murder case.

One question Alexa may not be able to answer paranoid owners, however, is how much does the Echo really listen to you? We look at how the Amazon Echo works and bust the myth on whether it's really spying on all your conversations.

How does Amazon's Alexa work?

As with its chatty rivals such as Apple's Siri, Google Assistant and Microsoft's Cortana, Alexa is activated by specific "wake words". For the Echo and Echo Dot, the magic wake word "Alexa". Users can also change this to "Amazon" or "Echo".

In fact, you can shout commands at Alexa all you like, but without saying its name you are wasting your breath. Once it does hear its name, it then captures your request, encrypts it and uploads it to cloud servers via Wi-Fi. The servers then unscramble your phrase and return with a response, be it an answer to a query, command or initialising a 'Skill' which are its abilities in the way of installable apps.

Is Alexa always listening?

Yes, but crucially it is not always recording. Alexa's always-on nature removes the need for a physical button on an Echo speaker, meaning you can have a natter with it at any time with just a wake word.

This fact has sent more than a few alarm bells ringing when it comes to privacy concerns, but Amazon is adamant that while Alexa always has an ear open during any conversation in its vicinity, it does not start to record, store or upload your speech until it hears "Alexa".

Can I stop Alexa from listening all the time?

Yes, but the real question is why would you want to? Tapping the mute button on top of the Echo renders the microphone completely useless. This causes wails of "Alexa" to fall on deaf ears.

What happens to Amazon Echo recordings and can I delete them?

The recordings are sent to Amazon's servers, reportedly for use in part of an industry-wide campaign to improve AI assistants using masses of voice data.

Those concerned with data privacy (or those who asked an embarrassing question they would like to scrub from the record books) can delete the recordings from within the Alexa app for Android and iOS, or through a browser on an Amazon account page in the My Devices section.

Whether or not this deletes the recordings from Amazon's servers completely is unconfirmed but at least your account will never show that extra large pizza you ordered at 2am.

Why is an Amazon Echo involved in a murder case?

In December 2016, Amazon denied a US court's request for access to the voice data within an Echo speaker to use as evidence in a murder trial.

According to law enforcement investigators, the Echo was streaming music near to the scene of the crime and around the victim's time of death, making any recordings potentially crucial in exploring the case.

Amazon has argued that an individual's recordings are subject to freedom of speech laws outlined in the US Constitution under the First Amendment, claiming that the search "warrant should be quashed unless the Court finds that the State has met its heightened burden for compelled production of such materials."