https://techcrunch.com/2018/08/01/snapchat-launches-its-first-speech-recognition-lenses/

Snapchat is today launching new lenses that respond to voice commands. The company says it’s now rolling out a series of lenses that will animate when users speak simple, English words like “hi,” “love,” “yes,” “no,” and “wow,” as opposed to taking some other action – like opening their mouth or raising their eyebrows, as has been the trigger for some of the company’s prior lenses that animate with special effects.

For example, saying “hi” in the new lens will launch an animation that surrounds you with a flock of chatty birds; “love” will play cheesy jazz music; “yes” creates a zoom effect; “no” puts you in an infinite photo tunnel; and “wow” puts a bow on your head and surrounds you with the word.