# How does Alexa utterance parsing work?

What are the basic principles/tools necessary to make something like Alexa utterance parsing?

For reference, Alexa allows a designer to define phrases with "placeholders" that will be filled in. For example, the phrase "what is the horoscope for gemini" would match the underlying model (below), and return Sign=gemini.

what's the horoscope for {Sign}
what is the horoscope for {Sign}
give me the horoscope for {Sign}
tell me the horoscope for {Sign}


To clarify: I am interested in the theory behind how the language model and parsing (with regard to theory and algorithms) work, so I can build my own version.

• I wrote an echo app a few months ago so my knowledge is rudimentary, but believe the actual speech-to-text is done at the device level (i.e. the physical echo/alexa unit). Text is then sent to a remote process, where it attempts to match the utterances in the skill set. Obviously placeholders like {Sign} function as arguments to functions whose values are supplied by the end-user/speaker. – Brandon Loudermilk Mar 6 '16 at 18:41
• Thanks @BrandonLoudermilk. I updated the question to clarify that I am trying to understand the natural language parsing aspects. – Matt C Mar 6 '16 at 19:10
• Speech to text and text to intent (NLP) are done on Amazon's servers; not in the cloud. I was also wondering the same thing. – Timmmm Apr 7 '16 at 7:08