Suggestions in chronological order:
1) First, email them asking for the right person to talk to. If no one responds to your email within 2 days, continue to next step.
2) Do a little LinkedIn research and find names of people you think might be the right people.
3) Call the company and ask the receptionist for the right person to talk to. When you ask this, mention that "I figured it might be [insert one or two LinkedIn names here], but I wasn't sure." If this doesn't work, continue to next step.
4) Set up a geographically targeted Google AdWords advertisement for your keywords ('event', etc). Make the geographic target restricted to within 1 mile radius of whatever company you're targeting. See here for instructions on how to do that: https://support.google.com/adwords/answer/1722043?hl=en
Do this for all of your potential clients.
If you'd like more detailed suggestions on these and many other methods, let me know.
best of luck,