What's in your home, always on, ready to listen to you and constantly adapting to the way you talk? Why, it's Amazon's Echo speaker. Think a less portable Siri or Google Now, but hands-free.

Are you ready to bring an eavesdropping device that's connected to the cloud into the privacy of your abode?

Here's how Amazon describes Echo on its site:

"Amazon Echo is designed around your voice. It's always on—just ask for information, music, news, weather, and more. Echo begins working as soon as it hears you say the wake word, 'Alexa.' It's also an expertly-tuned speaker that can fill any room with immersive sound."

According to the demo video, Echo answers trivia questions (Alexa, how tall is Mount Everest?), it tells jokes, helps the kids with homework and plays music on demand. You can ask it for a "flash news briefing" with the latest headlines. (The demo video features news from NPR.) And it keeps a running shopping list for you — it is from Amazon, after all.

You can put the 9 1/4-inch-tall device anywhere in the room (as long as it's near an electric plug), and something called "far-field recognition" — seven microphones using "beam-forming technology" — can hear you from any direction, Amazon says.

In a post titled " Amazon's new Echo device marries Sonos with Siri," Gigaom notes that Echo isn't the first device of its kind:

"There have been efforts to build these kinds of smart assistants for your home before. The Ubi aims to be a kind of intercom for the smart home, and the Aether speaker aims to combine cloud music streaming with voice input. However, Amazon's strength is that it could combine Echo with its other devices and services to make it a lot more valuable out of the box."

There's a button to turn off Echo's microphone, but as you can imagine, some people might be uneasy with a listening device planted squarely in their living room or bedroom.

As a commenter named Hicham Bouabdallah wrote on TechChrunch:

"NSA, CIA and FBI would like to personally thank Amazon for installing spy mics in every home. Having said that, love the idea of an always on personal assistant."

Echo also works away from home using a free app on Amazon's Fire OS and Android as well as desktop and iOS browsers. It's selling for $199, invitation only, though Amazon Prime members are eligible to get it for $99.

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