Do people understand what you need from them?  Do people get your point?  A quick way to check is to say, "echo it back to me."  Variations might include:

• Tell me what you heard so far to make sure we're all on the same page ...
• I want to make sure I've communicated properly, spit it back out to me ...

You might be surprised by the results.  I've found this to be an effective way to narrow the communication gap for common scenarios.