Jimlock
Adventurer
Face wall.
Place hands over mouth.
Whisper command word.
Refresh duration.
No need to worry about guards overhearing, unless you're less than a foot away.
Doesn't this seem to you as a lame way of resolving a challenge? The player(s) should think of intelligent ways to bypass relevant obstacles, and IMO this just isn't one.
Moreover:
I always assumed command words were the same volume level as the vocal component of a spell. I recall reading that vocal components have the same Listen DC as the sounds of battle, but I cannot find where the heck I saw that now. All the components section says is: "A verbal component is a spoken incantation. To provide a verbal component, you must be able to speak in a strong voice."
This
Plus:
Command Word
If no activation method is suggested either in the magic item description or by the nature of the item, assume that a command word is needed to activate it. Command word activation means that a character speaks the word and the item activates. No other special knowledge is needed.
A command word can be a real word, but when this is the case, the holder of the item runs the risk of activating the item accidentally by speaking the word in normal conversation. More often, the command word is some seemingly nonsensical word, or a word or phrase from an ancient language no longer in common use. Activating a command word magic item is a standard action and does not provoke attacks of opportunity.
Excuse my reasoning, but to me it seems that:
the holder of the item runs the risk of activating the item accidentally by speaking the word in normal conversation.
=
the holder of the item does not run the risk of activating the item accidentally by whispering it.