Voice control generally uses the microphone built into the device you are using. The better the mic, the better the results in most cases. High quality external microphones with features like noise canceling can also be purchased although they are generally used with computers and not mobile devices (although they can be).
On device versus cloud based speech recognition? In most cases the recognition happens in the cloud on mobile devices. This is important because no internet equals no voice control. As processing power improves in newer phones more features of voice control are happening on the device. This is good for privacy.
Voice control systems offer a variety of features to enable hands-free use; some of which include:
Taking the time to learn the commands for your device is important. Don't skip this step.
Use Microsoft Windows? You have options.
Option 1: Windows has its own speech recognition tool cleverly called "Speech Recognition." Check out our Windows Accessibility Features page to learn how to turn it on. They also offer a service called Dictation which is not hands-free. You can learn more about Dictation here .
Option 2: Dragon Naturally Speaking (or just "Dragon" to those in the know) - is a third party application made by Nuance . Dragon is generally considered the gold standard in terms of features and performance.