Yes. On June 29, 2002, just a day after OFP: Resistance was officially released, Amon Goeth's OFPR Sound Replacement addon was made available for download. It's available from LDD Kyllikki and other OFP fansites.
Not to be outdone, in early July 2002, OFP addon maker Munger released another soundpack, Battlesounds 1.0 for Operation Flashpoint Cold War Crisis/Resistance. This pack can be installed whether you have OFP: Resistance or an older OFP version. In September, Munger released version 1.1 of his soundpack. It's essentially the same as the earlier version but borrows some sounds from Satchel's Dynamic Range soundpack for older OFP versions. You should be able to find Munger's soundpacks at reliable OFP download sites.
IMPORTANT: Using a sound pack addon may affect your ability to participate in MP games. Read about it here.