Invisible, But Not In-Audiable

[Iso]

How would the DMs like us to handle hearing and understanding with a successful Spellcheck someone casting Invisibility from within close proximity, and then such an individual passing so close by that even the engine plays their footsteps on hard cobblestones?

Should not a successful stealth check be made while moving and invisible to not be completely noticeable to anyone who had already been made aware the spell was being cast, specifically by understanding what it is someone just did (casting the Invisibility spell)?

Peasants don't walk around activating words of power on their way to the grocery store, and if I heard a spell of that kind being spoken a number of feet from me and then heard footsteps of a regular walking pace pass within my personal space, I'd be quite disturbed and alarmed.

Also, another player has asked me to add the question of whether or not Invisible people cast shadows.

Thanks guys!

[Kaeldorn]

Move Silently and Listen checks are commonplace. Invisible people do not cast shadows.

Although if someone turns invisible right in front of you, with a listen check you can't immediately act like you 'see' them, you only know the general area where someone is and if you were to try and attack them I'd say make it a 50% concealment. Spells requiring a specific target are a no-no.

You may also be disoriented when all of a sudden someone disappears, but that's up to you.

[Iso]

They were out of sight, but not out of earshot - the walking occured within a single foot of me, so I imagine my character heard it as clearly as if someone else simply walked by. Thank you for the clarification on shadows.

Also, words of power must be spoken to activate spells that haven't been prepared with the Silent Spell Metafeat, so the action of speaking a spell out loud can be heard and identified by educated people, even if they're not in sight, isn't that right?

[Phantom Lamb]

You are right to act "alarmed" at someone casting spells in a populated area. The guards would be as well.

Please read the Wiki for other rules regarding stealth. There's a whole section.