Amazon Alexa will now listen for strangers in your house and keep it safe from burglars

Alexa is listening. And now she'll tell you if she doesn't like what she'll hear.

Amazon has announced that its Echo speakers will now be able to go on guard in your house when you're not there, keep an ear out for anything untoward.

If the microphones in the smart speakers hear the sound of smashing glass or a smoke detector going off, for instance, they'll record that sound and send it to its owner. All of that is done using the same kinds of artificial intelligence that power the voice tools and other smarts of the Echo.

The feature, known as Alexa Guard, was just one of a range of new features that Amazon announced as part of a major event that was host to some 70 updates. They include other software tools such as "frustration free setup", which allows new devices to be set up without fiddling with controls.

The Guard feature is set by saying something to Alexa such as "Alexa, I'm leaving". At that point, she will start her watch – or listening – and report anything unusual.

As well as listening out, Alexa can also turn lights on and off in a randomised way that makes it appear that someone is still in the house. And it will connect up with alarm systems from companies like Amazon-owned Ring to make sure all of those tools are working together.

As well as listening out for suspect noises, Alexa will also check to see if users are whispering. If they are, it will start to listen too, ensuring that it doesn't wake people up.

Amazon said that both of those listening features rely on advanced artificial intelligence that has been trained in detailed ways to recognise those sounds and react to them.

Other new Alexa features announced at the same event include Hunches. That allows the assistant to learn about how you use your house, and warn you if you seem to be deviating in a usual way – if it sees you're going to bed but have left your living room light on, for instance, it will alert you and ask if it needs to be turned off.

And in the event of the internet going down, which normally kills all the feature of Alexa, Amazon is also introducing local voice control so that devices can still be controlled.