Hound is a natural language processing engine with hands free app came from SoundHound Inc like Google Now, Siri and Cortana. Why we need a discussion about Hound as already we have Google Now or Siri? SoundHound Inc says that "Hound's Speech-to-Meaning engine delivers unrivaled speed and accuracy. Speech recognition and natural language understanding is done simultaneously and in real time. Compared to traditional approaches that perform speech recognition first, then send the result to a search or understanding engine, Hound does it immediately".
With Hound,You can speak naturally. No need to speak in fragmented keywords like in Google Now. Here is the usage and pros with compare to Google Now and Siri.
It has the ability to handle natural language sentences, including details, specifics, and multiple criteria example, of describing the hotel you want to find to have a gym, free wi-fi and be less than $200 a night)
It can even understand exclusions and negation (for example, if you want to find a place for lunch, but since you've had Chinese all week, you can say "show me restaurants nearby, excluding Chinese places" )
Interesting thing is Hound still in Beta stage. It is currently availabe in US with invite only. Here is the link to get invite.