Terminology is different in most areas of the world even if the country is English based. Highly tested humor that would work anywhere in the U.S. may fall flat in another country simply because the audience doesn't understand one of the words. For example, in Australia, break out sessions are called syndicates. If you were making a joke that used the word syndicate, you may totally confuse the audience and they won't laugh. People from most other countries will not relate easily if you mention miles per gallon or miles per hour. You should avoid talking about seasons, sports figures or celebrities that don't have world-wide name recognition. Rethink all humor you normally use and try to find problematic words. This is difficult to do by yourself. Try to find a person familiar with the local culture to help you.
When using translators, humor is tougher because timing and word play don't translate well. You might have to slow down considerably because of interpretation. Some speakers use half sentences to keep up the pace. This is very difficult and requires practice.
Speakers have been known to have fun with interpreters (of course, I would never do this). An unnamed speaker I know purposely mumbled to his interpreter to see what would happen. The interpreter mumbled back. Then the speaker mumbled again. It was hilarious.
Even when the audience speaks English they may not be able to understand your accent. Check with locals to see if you can be easily understood. You may have to adjust your normal delivery and rate of pitch slightly.
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