If someone is abusing you through voice or text chat, the best response is to block them.
How to block a person or object
When you block another Resident or an object, you cannot:
See text chat, hear voice chat, or receive IMs from that person or object.
See particles emitted by the blocked avatar or object.
Receive items from the blocked object.
Likewise, a Resident on your Blocked List cannot hear or see voice or text chat or receive IMs from you.
How to block someone
There are several ways to mute voice chat inworld:
Right-click on the avatar and choose Block.
Select Communicate > Nearby people, right-click the person's name and choose Block/Unblock.
Click the Chat button at the bottom of the Viewer window to open the Conversations window, right-click the Resident's name, then choose Block Voice and/or Block Text. Either option also visually mutes the Resident's avatar.
Note: If you IM with, Pay Linden dollars to, or give inventory to someone you muted, that person is automatically unblocked. Chat history informs you of what's happened.
How to block an object
After you block an object, you cease to receive messages or items from it.
First, locate the offending object. If the object is making noise, you can find it easily by selecting the following settings in the View menu: World > Show > Beacons. Then check Sound sources in the Beacons window.
Objects that are making noise are highlighted with a yellow beacon.
To block the object, right-click on it an choose Manage > Block.
Disabling chat popups
To disable incoming chat popup notices:
Choose Me > Preferences > Chat.
For Friend IMs, Non-friend IMs, Conference IMs, Group chat, Nearby chat, and Object IMs, you may choose a behavior from the dropdown menu. To prevent popup notices, choose No action and make sure that Play sound is not checked.
To disable notices from a specific group:
Choose Communicate > Groups.
Right-click the group and choose View info.
Un-check Receive group notices.
Allow only friends and your groups to call or IM you
To allow calls or IMs only from friends and groups to which you belong:
Choose Me > Preferences.
Click the Chat tab.
Check Only friends and groups can call or IM me and click OK.
Non-friends won't get any acknowledgment that you haven't received their message. You may want to note in your profile that you prefer not to be bothered.
This can be an alternative to selectively blocking specific Residents, and can be used in tandem with busy mode.