You're situation is a little different. In pursuit of someone, such as the scenario you described, police can use IR. Police cannot use IR to surveillance with out a warrant in the U.S.u dont need a warrant to use an infared in residential areas in the US. i got picked up by one in my teen years stealing fireworks out of a guys garagewith like three other kids. cops all swarmed with guns at pointed at us and shit. but u definately dont need a warrant to use one.
I have the 8" windtunnel fan with the lowes insulated ducting too and there is almost NO noise coming out of the hose. I can kinda hear the fan still even with my box I made for it but its quieter than a normal house fan on a stand. I am on laminate flooring and I bought some insulated white foam board from lowes too. It comes in a 4x8ft sheet I believe and comes in .5 to 2 inches thick. I put that under the grow tent to cut down the viborations to the lower neighbors and that worked too. Next grow I am going to wrap the fan in another box made out of cardboard and line it with some sort of insulation. I like quiet!. I just build a clone box out of cardboard and used one 140mm 60cfm computer fan that is rated at 16db and wow I can not even hear it working. I have to put my hand over the light trap I made for it to see if its on. Wish my big fan was that quiet.Everyone is going on and on about duct mufflers/boxes for your fans..... Pick up some insulated ducting from lowes. Its around $25-30 for 25'. It's amazing how well this ducting cuts the sound of my 424cfm 6" inline.....takes it down to what a 170cfm 4" sounds like on medium-low.