Siri, Android, Cortana - The big web companies have been using voice for years. With the fast maturing SpeechRecognition API, you can bring this functionality to your website!
With nearly complete implementation in Chrome, and a better than 50% of users browsing with Chrome - it's possible to expose a fair number of users to voice search. If you're using any of the browsers listed below, you should see a green microphone icon near the search box at the top of the site.
This version supports the default com_search and com_finder search fields (as well as both kinds of search modules). Additionally, you can define CSS selectors for other search fields.