We had discussions about this in some of the chat threads that I was a part of about 4 years ago.
The truth of the matter is that people can specialize in specific areas but most likely will not be an "expert" or "intellectual" across the board.
For instance the doctor that spends a number of years in school achieving their degrees and specializations will probably not be the same person who is adept at maintaining their books for their taxes. Both skills are something that require years of study... so it is important to realize that both people may be an expert in their field, but an accountant is not going to be able to do open heart surgery in the same manner that the surgeon would be able to. Likewise, the surgeon is not going to know as much as a CPA when it comes to being able to do his taxes.
I think that perhaps it is in the way that people talk, which may be more off-putting than just the fact that they are smart or intelligent. People who rattle off a lot of very fast "over your head" type jargon are going to be perceived as being overly intelligent. If you are wanting to bridge this gap where you appear less off putting, slow down your speech and don't use words that would require the average person to go and look them up in a dictionary. Bring your speech and conversation to the level of the audience's level.
As an advertising and communications major, the average age that you are trying to reach is about a 5th grade level. When you talk above this, you may leave some people behind... or scratching their head thinking that you are overly intelligent.
But the goal of all communication should be to communicate... not talk over someone's head! Right?
If you are chomping at the bits for more intellectual conversation-- then start hanging out with people who have your same area of interests... and jargon. This should help quite a lot!