Filters to create mutes

This is more a proposal than a request.

I have successfully used low pass filters to create a five layer velocity, extremely realistic horn from fortissimo horn samples.

I think it would be possible to make filters/eq to get a mute effect for many general midi instruments that have mutes in real life, but are not lucky enough to be a trumpet - Horns, Trombone, Tuba, Strings (, guitar?). Strings should be easiest, as there are many existing filters to get a con sordino effect, brass and strings. I haven't found free ones, though.

We have a synthesizer and a mixer, it should be possible to apply filters to existing soundfonts to get straight harmon, wa-wa, crown royal bag, and many other mutes. Maybe we can even set it up so that users can add their own filters if they'd like.

Filters don't need to be their own intstrument, even as picking up a mute doesn't suddenly make your tuba into something else. We could attach it to staff text (type muted, go to effects, add a filter) or articulations (+, O) This almost certainly would take more processing power to play back, but it would expand the amount of sounds composers could use by quite a lot, including very common muted brass that general midi simply doesn't cover.