Amazon Echo brings an always-listening assistant into the home

Amazon introduced Echo today, a cylindrical speaker controlled by a cloud-based voice service called Alexa. After hearing its wake word, the device can play music, answer factual questions, set alarms and add items to lists.

Seven microphones use beam-forming and noise cancellation so Echo can hear a request from across a room, even while music is playing. An accompanying Fire OS and Android application handles settings, lists and remote control. The invitation price is $199, or $99 for eligible Prime members.

Unlike a phone assistant, Echo is meant to remain in one shared place, available without touching or even approaching it. That convenience also introduces an unfamiliar microphone into domestic space. Its usefulness will turn on recognition accuracy, the breadth of supported services and whether Amazon keeps adding skills after the invitation period.