The Amazon Echo Dot is based on the DM3725, a Digital Media Processor from TI:
This convenient device includes a microphone and an ADC embedded that is always waiting for a keyword to wake up, then it processes and convert the audio into a sequence of characters, yes, just like Siri does.
The chip costs only 23$ so it is possible to design an Arduino shield and deploy them in strategic rooms: the kitchen, the living room and maybe the toilet 🙂 Imagine that those Arduinos are connected wireless to a Raspberry PI that controls the sound system or the central heating of the house.
Therefore, the PI will be able to control some appliances in the house with some verbal commands like “play music”, “start the heating”, etc.
Now image that the same commands are available on a web server. The only difference is that you need to type them but this allows you to do remotely the same things as you were at home.