And from our friends at the NSA...

The [Snowden] documents show NSA analysts celebrating the development of what they called “Google for Voice” nearly a decade ago.
...the Snowden documents describe extensive use of keyword searching as well as computer programs designed to analyze and “extract” the content of voice conversations, and even use sophisticated algorithms to flag conversations of interest.
The documents include vivid examples of the use of speech recognition in war zones like Iraq and Afghanistan, as well as in Latin America. But they leave unclear exactly how widely the spy agency uses this ability, particularly in programs that pick up considerable amounts of conversations that include people who live in or are citizens of the United States.
Spying on international telephone calls has always been a staple of NSA surveillance, but the requirement that an actual person do the listening meant it was effectively limited to a tiny percentage of the total traffic. By leveraging advances in automated speech recognition, the NSA has entered the era of bulk listening.
And this has happened with no apparent public oversight, hearings or legislative action. Congress hasn’t shown signs of even knowing that it’s going on.