V -
Depends.
If the bow is tuned correctly, the nock tightness has less effect than most people think when shooting at trad distances.
Now, that takes a little qualification. If the nock is so loose to allow frequent dry fires (due to the nock slipping off the string prematurely) or so tight that it takes one person to hold the bow and two others to push the nock on the string - all bets are off.
About the tuning part: If the bow is tuned correctly, the nock will leave the string as the string approaches centerline. (The paradox of the arrow causes a lateral deflection of the string.) In that case, a tight nock should be no louder than a looser one. If the bow isn't tuned, the tighter the nock, the more of a "plucking" sound is possible. That's a theory and YMMV.
For a target rig, I like a light snap and little to no slippage on the string. For a hunting rig, I generally go a bit tighter for "safety" since the conditions are less controlled.
Viper1 out.