Next time you are giving a presentation, encourage people to tweet all they want.
There is no better way to find out whether you have connected with your audience than to see how people are tweeting in real time. This is your best indicator on how well you are doing.
This is their brain's initial reacting to your presentation and you are appealing to the primitive brain, commonly referred to as the "crocodile brain.' This part of the brain is not used for deep thinking, so if it likes what you are presenting then they will use the mid brain and neo-cortex brain to justify primitive brain's conclusion.
This will help you on whether what you presented worked or need to be changed.
So, don't do surveys, but just track the hash tag you created for the presentation to find out how people reacted to it.