Based on Mute Bards by YayRP.
This addon allows you to mute bards in cities/sub-zones that you specify.
The mod comes with a preset list of some of the zones with bards. You can add to or remove from that list as you see fit. Getting the subzone name for the current zone can be complicated. I recommend using AUI MiniMap (which shows the subzone name).
Type /mutebards to view and edit the list of zones (or go to Settings > Addons > Mute Bards 2.0).
Want to hear "Red Diamond" one more time? No problem. Remove it from the list.
Mute Bards doesn't interfere with your music, footsteps, or dialogue volume. Effects will always play at the default 70 volume during combat.
This is all based on a messy hack that involves singling out zones where Effects are most annoying and selectively turning them off. Side effects include, but are not limited to: no sound when you burglarize people's nightstands in bard zones, roll dodge tumbling sound, whistling for a mount.
One last disclaimer. I have added functionality to allow you to refresh the muting effect without leaving a zone, but if you reload UI, while you're within a zone, refresh won't work until you change zones again. This is because I temporarily store the last zone you entered (thus the zone you are currently in) but reloading the UI will delete that variable, so I won't be able to know what zone you're in the next time you hit refresh.