First of all, make sure your guests know that it is always best to hold conversations with line of sight, which means that you can see the speaker's face while they are speaking. You can also scan your environment for potential trouble spots such as rooms with too many hard surfaces, or very large rooms that echo.
For restaurants, this can be especially challenging. You can do some things to help communication flowing. First look for soft surfaces, second never sit in the middle of the room, and look for booths with high backs. By taking a few preventative steps before you have problems, you can reduce auditory fatigue and improve your understanding of speech.
If you have hearing loss and have not made the leap to hearing aids, you can also try these things to help you understand speech better.
Happy Holidays from The Hearing Station.