We've struggled with the same. We have made earplugs available to those in other areas, if they choose. When it comes to routing acrylic, we just grin and bear it. My operator wears hearing protection when routing, or using the oscillating tool for a length of time. We though about acoustic panels as well, but they're cumbersome and won't fit well in our space.
the oscillating tool on the Colex machines are quite loud due to the engineering and metal on metal sound.
For routing, usually a good sign of cutting acrylic is quiet.
You will need to determine if your excessive sound is due to the material contact with the blade of if it is debris in the spindle altering the balance during rotation.
The longer the bit, especially unnecessarily CEL cutting edge length, will cause extra noise due to vibration.
Your colex machine does have the benefit of low RPM operation and a variety of collets to use.
While they are a competitor, i would advise you to look at your dieline.
Can you get away with a 8mm CED DLC coated bit?
this is a bit wider than standard 6mm but you can cut in 1 pass at a relatively decent edge quality.
Invest in cleaning your spindle and look at the coated tooling.
the Superior coated 6mm bits are good.
You will also need to look at the material.
some have a lower melting point etc.
There isn't a general rule saying you need to use the highest rpm to "continually "mulch" debris while generating hear and wear.
Take the time to set up 6" lines to cut on centerline with varying feed rates and RPM.
make notes on material and adjust your tool library when applicable.
If you have more questions, everyone is welcome to email me.
raumdivarco@cwtworktoolsusa.com
As a former end-user i take all of these things into account to improve our machines and software offering.
I do like sharing information and helping the community.