First off - verbal component from 100 (or more) feet away, probably won't alert anyone on the other side of that door, right? Will it alert everyone within range of the wizard, though? (Always assuming he doesn't have it Stilled.) Are there any RAW rules for echoes?
Also, does the door (or chest, etc) make any noise by popping open? If the door opens onto a short corridor, will the guards at the end of that corridor notice that the door just popped open for no damn reason, or do they require an alarm in place?
-1 to preception for every 5 feet past... 20 i think. so to hear a dc 5 at 100 feet is -16, + 10 for the door, to what ever they roll.
and i think dc 5 in a stone hall way to hear a door open, unless they roll stealth to do it, but its gms call if stealth would effect it at all.