the latest teamspeak beta has a great option for lowering all other sound (like music, sounds from the game, whatever else is playing on your computer at the time) while you are receiving or sending on teamspeak; it is even configurable as to how long to keep the sound lowered, and how much to lower it!
go to Settings->Plugins and enable the VolumeControl plugin. Then on that same page, lower left, select settings, make sure the "enable" is checked, and configure it the way you like! note that volume suppression rate is actually suppresed volume; ie 0% means muted when someone else is talking, 100% means no change; i set mine at 25% with a 3 second delay to see how that works out.
go to Settings->Plugins and enable the VolumeControl plugin. Then on that same page, lower left, select settings, make sure the "enable" is checked, and configure it the way you like! note that volume suppression rate is actually suppresed volume; ie 0% means muted when someone else is talking, 100% means no change; i set mine at 25% with a 3 second delay to see how that works out.