name the effect?

I'm shooting a film on Social Anxiety...Part of a scene is the student who suffers from social anxiety, is asked to remove his hat in the classroom...the effect I want to put in, is as the camera moves toward the student, I want to have his own voice and others laughter heard around him, kinda like the clip below
https://www.youtube.com/watch?v=sgo6kwaAXSc

Whats this effect called?
 
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