Amazon has announced that its Echo speaker has gone on general sale in the US, more than seven months after it launched as a private invite product, Digital Spy reports.

The voice-activated speaker will set you back $199 or $149 if you are an Amazon prime subscriber.

The Echo uses seven microphones and has noise-cancelling technology to hear commands even when it is playing music. It also produces 360-degree audio and is Bluetooth-compatible, enabling music to be played via audio apps like Spotify.

The Siri-like personal assistant links up with the cloud, running on Amazon Web Services, and has companion apps on Fire OS and Android, with a web-based app currently used for iOS.

Last month, Amazon rolled out an update for the speaker that enabled users to shop online with it via voice commands.

Amazon claims that the Echo proved popular during its invite-only trial, fulfilling an order backlog.