How technical should my oral PhD defense be? I thought this would make a good question, and will ask my advisor shortly.

In the fields of optical sciences, electrical engineering, or applied physics at an RU/VH institution in the United States, how technical should the oral PhD defense be?

My last conference talk did not get any questions (on the same topics in my dissertation), so I believe that my presentations may be overly technical.

For some context : This work, some recent work by my former labmate, and recent work in this same niche by my advisor have been heavy on the mathematical/theory side, and none of us have received many questions at recent conferences.
You need to find out what the standard is in your department, since it varies. You can:


ask your advisor 
attend other defense presentations in your department
ask students in your department who have successfully defended