A voice command device (VCD) is a device controlled by means of the human voice. By removing the need to use buttons, dials and switches, consumers can easily operate appliances with their hands full or while doing other tasks. Some of the first examples can be found in home appliances with washing machines that allow consumers to operate washing controls through vocal commands and mobile phones with voice-activated dialing.
Newer VCDs are speaker-independent, so they can respond to multiple voices, regardless of accent or dialectal influences. They are also capable of responding to several commands at once, separating vocal messages, and providing appropriate feedback, accurately imitating a natural conversation. They can understand around 50 different commands and retain up to 2 minutes of vocal messages. They can be found in computer operating systems, commercial software for computers, mobile phones, cars, call centers, and internet search engines such as Google.