If others speak gossip -
1- explain gently & firmly that it is not permitted.
2- if that will make things worse , change the topic
3 - if that fails - leave the scene or use your fingers as ear plugs.
4 - if that's not possible
A - decide not to believe the words ,
B - to be upset with being there
C- sit as a silent stone & better yet with an angry face.
***
Think ahead - avoid such a group
Don't live in such areas or sit near such people.
Now may be a good time for a gem of Torah study.
www.GemsofTorah.com