This will likely come naturally as you play campaign or even quicker in survival as enemy waves typically pass over dead enemies. Simply set as many traps on enemies you’ve killed.
If you want to get this really fast, load up the first campaign mission. After using the zip line, there will be one enemy overlooking the dam. Sneak up to the crates on the right side and place a teller mine. Fall back to cover and shoot the soldier in the leg to get his attention. He will run to the crates for cover. Before he reaches the teller mine, create a save, then resume. After the soldier dies from the mine, reload your save, and rinse/repeat. You’ll have 50 within a few minutes.
There is also a persistent sound mask at this location and you’ll get credit toward the sound masking achievement at the same time: