Edit: moved to peace-bonding thread
http://forums.fanime.com/index.php/topic,16577.0.html (http://forums.fanime.com/index.php/topic,16577.0.html)
Delete this thread if necessary.
The place to ask is the Peacebonding thread: http://forums.fanime.com/index.php/topic,16577.0.html
If you read the code of conduct (http://www.fanime.com/code-of-conduct/2014-2/) it says "Certain items are not allowed on premises: laser pointers, fog machines, strobe lights, megaphones, and other noise-making items." so I guess that would include trumpets, however I've seen multiple people with musical instruments at FanimeCon, so it might be allowed.
My mistake. If someone can move this into that thread, that'd be great.