talk over head
talk over (one's) head
To talk about things that one cannot follow, understand, or comprehend. Your presentation shouldn't focus on the technical details too much; you don't want to talk over everyone's heads. I hate the way he always tries to talk over my head, as if I'm too dumb to understand what he's talking about.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
talk over someone's head
Fig. to say things that someone cannot understand; to speak on too high a level for one's audience. The speaker talked over our heads and we learned nothing. It is not a good idea to talk over your audience's heads.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.